What is the bicycle derailleur B screw and and how to adjust it?
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- čas přidán 8. 09. 2024
- What is the b screw on the rear derailleur and how to adjust the b screw: Most derailleurs have some form of adjustment for the spacing of the guide pulley to the cassette cogs. This spacing is controlled by adjusting the b screw on the rear derailleur. This adjustment is check when the chain is on the smallest sprocket up front, and the largest cog in back. The majority of road bike and mountain bike derailleurs require a gap between 5 and 6 millimeters between the guide pulley wheel and the largest cog on the rear sprocket. You can use a hex wrench to gauge this distance. We'll demonstrate the b screw adjustment on a Shimano XT derailleur.
Rarely do you need to adjust the B screw. If you’re changing cassette to a smaller or larger size (cog) or replacing your derailleur with a different length (long cage derailleur) or manufacturer’s make, adjustment may be necessary*. A gap that is too small will result in “pinching” of the chain and a rumbling sound (or bicycle strange noise) while pedaling. And if there is contact between the teeth of the large chainring and the guide pulley wheel, damage to the plastic guide pulley teeth may occur. Check when performing bike maintenance.
If the gap is too large, poor shifting may result and you may note the chain skip 2 or 3 cogs as you shift out of the largest sprocket.
If the bike is shifting well, the B screw is probably within acceptable adjustment range. To increase the gap, tighten the B screw. To decrease the gap, loosen the B screw. If you do make significant changes to the B screw, double check the indexing adjustment. This may also be important in normal bicycle maintenance and repair on older bicycles.
*The B screw adjustment seems to be the most crucial when you are running at the limits of the derailleur capability (see references below). Most derailleurs have certain limitations. These includes the maximum difference in chain rings and the drivetrain capacity, and maximum cassette size (included with the manufactures specifications). On my compact (34/48 front chain rings, 11/34 cassette, and Shimano Deore XT long cage derailleur), the maximum difference in chainrings is 14T, the largest sprocket that can be handled is a 34T. To find the drivetrain capacity, take the difference between the large and small chainring and add it to the difference between the large and small cassette cog. On my compact that’s 14 + 23 = 37. I’m within all the specs: max difference in chainrings: 22T, largest cog: 34T and a capacity up to 45T. Note that the closer you are to the manufacture’s derailleur limits, the more important the B screw difference become, at least in my experience.
REFERENCES:
Derailleur Capacity: What is the max my derailleur can handle:
www.mantel.com...
Rear Derailleur Buying Guide:
guides.wiggle....
Needed instruction to run a 34t with new 40t cassette on a medium cage derailleur and your video couldn’t have been done better. Already had the screws, but needed the tutorial.
Glad it worked. You can also use a "hanger extension" as well (cost less then $10 on Amazon). Regards, Tony
Thank you for including video of the b-screw being both too tight and too loose! All of Park Tool's videos just say to set it properly, without going into much detail about how to recognize when it's not set properly.
You're Welcome. Our aim see to make clear what other bike mechanics skip over.
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Regards and safe cycling, Tony
Thank you for a perfect explanation. I never had to use the lower gear on my bike, I've ridden 2000kms and just last weekend I put a trailer and went for a touring ride. With the load of the trailer I had to use the lowest gear and it was rubbing and doing noise. I adjusted the B screw, not being sure what I was doing, just following my common sense, and it worked perfectly. Its disapointing that from the factory it was wrongly set, it was too close to the lowest cog. You confirmed with this video that I did the right adjustment. Chers from British Columbia Canada!
The "b" screw setting will depend on the size of the cassette used. It's not so much the manufacturer as the shop who sold you the bicycle that should have tested it out after installing the cassette. Glad you figured it out. Good work. Regards and safe cycling, Tony
I had adventure with B-screw. Accidentally played with it, and after that three very good mechanics spent hours trying to tune the derailleur. 12x SRAM is very capricious.
If it's a 1x, it requires some extra info. See:
czcams.com/video/cxZVXVyedf0/video.html&ab_channel=SickBiker
If you're running a SRAM Eagle, see:
czcams.com/video/LQXZiUShErU/video.html&ab_channel=SRAMTECH
As we get up to the 12 speed and bikes become more complex, so do the adjustments as we can see in the above video.
Really helpful. I'm in the middle of installing M591 sgs rd on my 10 speed 105 road bike so I can run a 11-36. Nobody talks about getting the M4 X.7 nut. That trick is really handy. I knew about the longer M4 bolt from Harris Cyclery but the nut tip was awesome.
You can also use a hanger extension (cost around $5) which works well. Regards, Tony
@@tony10speed thanks Tony. How do you fine tune the B-screw with a nut? I have the hanger extender but the I don’t think I need it. I just want to bring the guide pulley closer to the 36t cog to improve shift performance.
@@faisal0280 You need a friend to push the derailleur forward to take pressure off the "b" screw while you hold the nut and tighten the screw. It's much easier with a rear derailleur hanger extension which is now my method of choice. but before buying a hanger extension, one needs to read the info on the hanger extension to make sure it will work with your combination of derailleur and cassette size.
Regards, Tony
@@faisal0280 You need a friend to push the derailleur forward to take tension off the "b" screw while you hold the nut and tighten the screw. It's much easier when working with a hanger extension which is now my choice (they're relatively inexpensive). Just read the specs before buying one to make sure it will work with your chain speed and cassette size.
Regards, Tony
@@tony10speed thank you Tony
I recently bought a brand new bike and apparently the shop I bought it from did not do a great job with setting up my chain... I kept hearing a rattling noise and this morning it fell off on me while I was biking to work, looks like it's just too loose. I managed to finish my commute by switching to higher gears but this should help me get it fixed without too much pain, thank you for sharing!
What do you mean "fell off?" It may be, as you say, the chain is not properly sized and is too long. Here's how to set the proper chain length;
czcams.com/video/Vg2SoOOrpE8/video.html
I, personally, would take the bike back to the dealer and complain - have him set it properly.
Let me know how you make out. Regards, Tony
Thanks! The 4 to 6mm gap is what I was looking for.
11-34 Deore XT with a 105 Long Cage Derailleur
Some of the newer derailleur cages come with a plastic gauge to accurately set the "b" screw, but a 4 mm hex key often works for many others. Also visit our CZcams home site at:
czcams.com/users/MrTony10speed
Regards and safe cycling, Tony
Thanks for the nice video. These screws are simple once you get a demo of why they are important. I had a bike which had always had clunky shifting since new. I rode it for years and even after replacing the cabling with fancy Teflon coated versions, it still was clunky. Turns out 3 turns of the b screw solved my problem. The bike came improperly adjusted from the factory haha.
Good work Sherlock. Thanks for the feedback. Regards and have a pleasant and quiet ride, Tony
Thank you...wasn't sure of the gap needed between the cassette and the pulley...now I do!
You're Welcome. Also visit our CZcams home site at:
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Regards and safe cycling, Tony
Perfect description of the B screw function, thanks
You're Welcome. Also visit our CZcams home site at:
czcams.com/users/MrTony10speed
Regards and safe cycling, Tony
Your videos have enhance my understanding of how to tune and maintenance of bicycle. Thank you sir.
The "b" screw can be important in adjusting the distance between the guide pulley and the cogs. This is important for smooth shifting. Thanks for the compliment. Safe cycling, Tony
Very well explained and demonstrated. I want to change out my 11/28 for an 11/32 for when I hit the hills. However, I don't want to have to change the rear derailleur to a long cage and hopefully, I can keep the same chain too. Thanks for the video I think this will help a lot. JP
You need to look up the total capacity of your present derailleur (i.e. the largest cassette cog it can handle as well as the number of teeth capacity: (number of teeth on the front large chain ring-number of teeth on the small chain ring) + (number of teeth on the large cassette cog -number of teeth on the smallest cog). My experience is you'll need a longer cage derailleur. You will also need a new chain since the present chain will be to short as a result of the larger cassette cog. If you use the same chain and you are in the big chain ring and accidentally shift to one of the large cassette cogs, your chain will jam and could lead you to crash. Regards, Tony
All thumbs up on this B screw adjustment explanation. Got me dialed in on that little bugger. Thanks.
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Regards and safe cycling, Tony
What an excellent video. Concise, interesting and well presented. I've learnt more about the rear derailleur than I signed up for! Thanks Tony!
Thanks. The rear derailleur has more to it then we think. We often don't have to deal with the "b" screw but in my shop, we are constantly restoring or upgrading bikes which lead us to fine adjustments of all types. As we add larger cassettes/long cage derailleur/hanger extension or convert to a 1x chainring up front, we need to look at such things as the "b" screw. Also see:
czcams.com/video/pMrOs3P9nn8/video.html&ab_channel=SickBiker
Regards, Tony
This is super important on modern derailleurs with a clutch. If you have a lot more than the 3-5mm between the biggest sprocket and jockey wheel then your shifting starts to go bad. (You may think it's cable tension but its usually the bscrew)
This typically happens when you replace or resize your chain (Too many or too few links).
Rule of thumb: If you have a big gap between the biggest sprocket and top jockey wheel, anti-clockwise the bscrew to change the angle, then when you engage the clutch (unlock the cage) it will take up the slack.
Thanks for the added and important tip. Well explained. Regards, Tony
Nice work Tony ❤
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czcams.com/users/MrTony10speed
Regards and safe cycling, Tony
Thanks.
I've just had an interesting situation - i fitted a larger RD & cassette, and it appeared that i didn't even need the B screw at all, so i took it out. 😃 I discovered that when in the small front chainwheel & smallest cog, the chain was actually loose, and i was occasionally dropping the chain. Re-installing the screw and adjusting it fixed that problem
Thanks for the comment. I'm sure it will help inform others. Safe cycling, Tony
I did same but it won't fit and there is like another screw inside is there any fix plz way if there is😢
@@mhboruto6644 Not sure I understand your problem without more details.
THIS IS AWESOME TO KNOW THANK YOU FOR THE TIPS :-) ESPECIALLY THE B SCREW
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Regards and safe cycling, Tony
This is a great hack and really clearly demonstrated. Thanks! I had the same issue as the demonstration when upgrading my Shimano Tiagra 4600 setup to an 11-32. My solution was to shorten the chain (right to the minimum!). With the tension pully fully engaged it gives a few extra mm of clearance for the guide pully. Perhaps that's how the manufacturer spec'd it on your system? I much prefer your solution allowing for a few redundant links in the chain in case of emergencies on the road -so long as the extra distance doesn't cause sloppy shifting on the smaller cogs.
Let me know how you make out. Regards, Tony
Great help. I had the longer bolt but I gotta get the nut. My system is 44/36/24 13x 34 7speed system. That should solve my issue on several old bridgsetone mtn bikes.
Thanks for the information.
You might also consider a hanger extender. The following shows installation of a Wolf Tooth extender but, for a seven speed, you'd want to use a cheaper extender such as the following:
www.amazon.com/Keenso-Derailleur-Extender-Bicycle-Extension/dp/B0852WGR61/ref=sr_1_1?crid=3GN6UQI05QTZK&keywords=bicycle%2Bhanger%2Bextender&qid=1647522415&sprefix=bicycle%2Bhanger%2Bextender%2Caps%2C78&sr=8-1&th=1
Either way should work. Let me know how you make out. Regards, Tony
Hi Tony,
I had no clue there were such things as derailuer extender. For now, since I can shift into the rear 34t with just a little bit touching of both guide pulley and 34t on cassette, I will use your hack. Out of my Bridgestone mtn bike fleet of 30 bikes equipped with 34t rear cassette, I only have the problem with just a few of them.
Thanks for sharing and I'll report back later.
A rainy spring day here in the Pacific NW.
Jim-
What is the purpose of the nut attached to end of the m4 x 25mm bolt? I can't see the video well. Is the nut adjusted in addition to bolt
@@jimlegalley6656 The nut sits at the end of the new longer "b" screw, moving the "b" screw back a bit further. This in turn moves the guide pulley down a further away from the largest cassette cog. It's similar to extending the derailleur hanger.
Nice one Tony, thanks v much !
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Regards and safe cycling, Tony
Hi Tony,
Thanks for your explanation. I get it now.
I'll be sure to checkout your other videos. You helped me out alot!!
Jim Le Galley
Glad it was helpful!
I've had to adjust my b-screw to reduce the gap because the chain was coming off the jockey wheel during bumps. Reducing the gap also creates more chain to wrap around the jockey wheel.
It also places the chain and pulley wheels closer to the teeth of the cog leaving a lesser gap when you hit a bumpy section of road. Thanks for the tips. Regards and safe cycling, Tony
Excellent vid, informative on lots of levels.
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Regards and safe cycling, Tony
excellent video Tony, thanks!
You're welcome. Also visit our CZcams home site at:
czcams.com/users/MrTony10speed
Regards and safe cycling, Tony
straight to the point! thanks stranger :)
We try our best, thanks. Also visit our CZcams home site at:
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Regards and safe cycling, Tony
Thank you.That's a good hack ! Good job !
The hack works most of the time, but you can also use derailleur hanger extension which are inexpensive. Thanks for the compliment and safe cycling, Tony
I appreciate the video. I needed the info, and you had it. Your the man.......!
You're Welcome. Also visit our CZcams home site at:
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Regards and safe cycling, Tony
Nice hack Tony. Took me a long time to find this video. Suggest changing the title that includes something like larger cog/cassette with short cage so it's easier for people like me to find.
Thanks for the tip on title. Regards, Tony
I find I can get a little more good shift life out of my cassettes as they wear by adjusting the b limit. If I can't hit the spot with cable tension and know my cassettes are wearing, I can usually adjust my B limit a few times before getting a new one.
If you wait long enough the the top of the teeth wear down, you've probably waited to long to replace your cassette and have promoted increase chain and chainring wear. This is how I approach cassette wear:
czcams.com/video/g5uqTNmikro/video.html
useful vid maybe the best on the topic
Thank you. Also visit our CZcams home site at czcams.com/users/MrTony10speed
Regards and safe cycling, Tony
This was great.
Thank you. Also visit our CZcams home site at:
czcams.com/users/MrTony10speed
Regards and safe cycling, Tony
Excellent guide, I went from a 11-34 to 11-42 , using a longer B screw, its tight but the derailleur clears all the cogs, I had the top jockey set too far from the largest cog, didn't realise the gap was around 6mm so might improve my shifting, I tried a hanger extension on a larger 11-46, it is a long cage derailleur, the bike didn't like it, slipped under load wrecking the mech and damaging the cassette teeth, expensive mistake, seems 9 speeds max is a 42, God knows how folk make a 50 rear cog work.....
The 50 rear cog cassettes are often associated with a single front chain ring. You need a specific rear derailleur (as well as derailleur hanger) that is made for the large variation from small to large cassette cog that are present on newer bikes.
As far as retro-fitting an older bike - I've never had good luck with hanger extensions myself and most rear derailleurs have a limit on how large a cog you can use.
Thanks for the information and safe cycling, Tony
@@tony10speed Thanks Tony, from England
Thank you, that was so helpful. One more problem solved!
Glad to be of help. Also visit our CZcams home site at:
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Regards and safe cycling, Tony
Done something simler with shimano rear mech to fit a 40 tooth rear cog , but I just used the screw and it bent which sort of helped it fit the extreme angle of wher the screw push against the mech dropout , a nut on the end would have helped a lot I think
Great minds think a like. On one of my bikes, the derailleur hanger wasn't long enough to accommodate the b screw. Did exactly as you did, and now it works fine. On another bike I purchased a hanger extender which took care of the problem. Thanks for your input. Regards and safe cycling, Tony
@@tony10speed thanks that's a high complement coming from you sir,
I just try my best with whatever is at hand, my current set up is a 11speed shifter with 10 speed mech on a 9 speed caset and it works pretty decent,
Thanks for the reply and great vids take care and good luck
That's awesome, thank you 👍👍
Thanks Raheem. Little talked about topic. Regards and safe cycling, Tony
@@tony10speed happy riding, my friend 👍
I had poor shifting going down the cogs it would shift up fine to solve this i had to loosen the derailleur hanger bolt slightly then everything works nice. M735 xt deraliur. Maybe add some thread locker.
Loosening the derailleur hanger bolt is not an ideal solution. I wonder if the derailleur hanger is bent. Might want to check with you local bike store to play it safe. Let me know how you make out. Regards, Tony
@@tony10speed I'm not sure but i think it could be the ebay seller i baught it off may have swapped the anchor bolt with one from a different model. They do things like that to get sales, if original bolt was scratched or rusty they just take one out of a Acera or SiS or something similar.
Wow, thanks man!
Something not often talked about but important to check out when you buy a new bike (that the "b" screw is adjusted correctly) or if you change derailleurs. Regards and safe cycling, Tony
@@tony10speed thanks man, i have a brand new cassette, chain ring, chain, cable and i still hear a bit of crunching when trying to index my gears. The derailleur has some play where it mounts to the hanger, is that normal?
@@MaquinasDePalomitas No, it is not normal for the derailleur to have some play where it mounts to the hanger. The hanger may be damaged or bent (if it's replaceable, that's an easy inexpensive job). See:
czcams.com/video/qHK6jQizIdc/video.html&ab_channel=TonyMarchand
and
czcams.com/video/dAZ2uaazr7o/video.html&ab_channel=derailleurhanger.com
Make sure the derailleur is torqued correctly to the hanger. If tight and you still have play, the derailleur may be broken and need replacement. You're local bike shop can help you out here. Regards, Tony
@@tony10speed Thanks Tony, you really go out of your way for your subscribers, fan for life here! The hanger is relatively new and looks straight, the bolt is torqued to 11 nm (sram eagle gx), I checked out my buddies derailleur and it has the same lateral play. My shifting is pretty acceptable, just want it to be buttery smooth and get rid of the crunching. Since watching your video I’ve been playing with the b screw, when I get it so the guide pulley is really close to the upper gears it shifts like a dream, but then it won’t shift to the granny gears. I’m gonna keep toying around with it. Gonna watch this vid a couple more times so the info sinks in a bit more. BTW, love your EMT uniform, looks kick ass.
@@MaquinasDePalomitas You may be interest in the follow video from Sickbiker:
czcams.com/video/pMrOs3P9nn8/video.html&ab_channel=SickBiker
Tony
Great video Tony, I was looking for this tips for a long time :)
An additional note is that if the b-screw is not adjusted when in the small chainring, biggest cassette cog - such that there is too wide a gap between the tension pulley wheel and the largest cassette cog of greater then about 4 mm - you may get poor shifting, sometimes skipping cogs when you shift. So the gap is important. Usually you won't have to tapper with the b-screw, unless you're replacing the derailleur, changing the cassette size (making sure your derailleur can handle any larger cassette), or setting up a new bike. Regards, Tony
@@tony10speed Thanks for another great advise. I've done what you said, the gap was too big indeed. The derailleur is not shifting into the smallest cog now. Should I play with H screw or it something with gear cable tension? I've got SLX RD-M670-SGS derailleur. Thanks again. BR. Emil
@@emilwaszkiewicz7744 If turning the H screw counter clockwise doesn't solve, you probably have to much tension on the rear derailleur cable. Turn the barrel adjuster on the rear derailleur (for Shadow derailleurs such as yours use the barrel adjuster on the down tube or up near the shifter) clockwise (inward) until it shift to the smallest cog. If none of that works, you'll need to reset the cable tension of the rear derailleur.
Shift all the way to the highest gear (smallest cog), even though it won't go into that gear. Release the cable by unscrewing the rear derailleur cable pinch bolt. The derailleur should move to the smallest cog. Set the H screw by looking from the rear to line up the tension pulley with the middle of the smallest cog. Turn the barrel adjuster on the derailleur (Shadow derailleurs do not have a barrel adjuster on the derailleur and you would adjust the barrel adjuster on the down tube or up near the shifter) all the way in (clockwise), then out about 1/2 turn. Same for the barrel adjuster on the down tube or up by the handle bars if present. Now take the tension out of the cable by pulling on it with some long nose pliers (firmly but not with force) and tighten the cable pinch bolt. Now you're ready to start adjusting the index shifting with the barrel adjuster at the derailleur (or the barrel adjuster on the downtube or up near the shifter). Turn the barrel adjuster out (counter clockwise) until you get a nice shift to the next larger cog, then turn it another 1/8 turn. You may have to play with the barrel adjusters until you get smooth shifting throughout the entire range of cogs. Let me know how you make out. Regards, Tony
@@tony10speed I've tried this morning and - everything works fine now, like brand new :) I'be bought this bike from ebay in a very good deal. Rear derailleur was operating terribly. I've swapped hanger, rear gear wire and chain. Alignment was needed - what I've managed to because of your fantastic help. Many thanks again :) I just have to bleed hydraulic brakes and will be sorted. BR
Emil
@@emilwaszkiewicz7744 Good work and it sounds like you're ready to ride. Regards and safe cycling, Tony
Great, thanks you!
You are welcome! Regards, Tony
Hi Tony. Thanks for the video. Could you just clarify what that nut does on the end of the longer b screw? I was assuming it would be a lock nut, but that doesn’t seem to be the case. What is the reason for ‘lining it up with the end of the hanger’?
In the case, the hanger was not long enough and the "b" screw length was not sufficient to keep the pulley wheel from hitting the teeth of the largest cog. What I did was to use a longer screw of the same size and threading (available via the internet).The screw extended beyond the hanger so I put a small nut on the end and this allow the proper clearance. Another (and perhaps better) way is to use a hanger extender which will allow the "b" screw to properly be adjusted. I hope this make sense. Thanks for asking, Tony
appreciate your video. My b screw doesn't seem to do anything. It's hitting the hanger's tail at an angle, not really contacting that surface squarely like your video demonstrated. Now I wonder if the threaded part is bent out of position.
A short or even medium cage derailleur with a large enough cassette cog may result in this problem. Look at the specs for your rear derailleur which will tell you the largest cog you can have on your cassette. You may be able to accommodate a slightly larger cassette cog then the specs if you install a longer cage rear derailleur or a derailleur hanger extender. Here's a video on Wolf Tooth Hanger Extender:
czcams.com/video/eXemxzz1ctU/video.html
There are less expensive hanger extenders (at Amazon) that work just as well and maybe worth a try before replacing the rear derailleur.
Let me know how you make out. Regards, Tony
Thank u
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Regards and safe cycling, Tony
Tony, you may have saved my 11-28T to 11-32T upgrade on my SRAM Rival set! The factory B-screw just doesn’t give me enough clearance to avoid the chattering.
You can also obtain a "rear derailleur hanger extension" which only cost a few dollars that would allow you to set the "b" screw. I've done this for 2 different older road bike in which I could not set the "b" screw with great success. Did not have to replace the "b" screw with a longer one. Just an idea. Regards, Tony
@@tony10speed LOL, just ordered on Amazon! That, plus a new chain. Heard I’ll need a couple extra links. I’m running a new cassette so no big deal.
Thanks for the follow-up. Great video!
Hey Tony. nice video!. I found it trying to solve a problem i have with my b screw. It misses the bit of the frame. in other words is not able to adjust the polley angle hence, it is too close to the cog set. Do you have any idea on how to go around this issue? greetings from Colombia....
You could try a "hanger extension" from Wolf or several other manufacturers. I purchased several on Amazon (about $5 apiece). One removes the rear derailleur, attaches the hanger extension and then attaches the derailleur to the hanger extension. The "b" screw now comes in contact with the extension and can be adjusted. You can also replace the "b" screw with a longer one; put a nut on the end so it contacts the rear of the hanger and to sit further back. Finding the correct hardware and installation for this latte hack is tricky and difficult. Regards, Tony
My Shimano STX Derailleur (11-28 casette and 24 chainring) is still hitting the casette with the screw all the way in. I already checked for bent cage and hanger, but it looks straight. My chain is the right length too and everything is original to the bike. Any ideas?
Are you running a single chainring, double or triple and how many teeth on the other chainrings up front?
Also, is the derailleur a short or long cage Shimano?
2:00 "make sure cassette can accommodate chain length" I forgot this once and accidentally changed into the big ring and new bigger sprocket. End result I immediately bent the frame on my AMP B4 (old school hyper expensive MTB frame).
Tough lessons learned. Regards, Tony
So a slightly longer chain wouldn't have had an affect on the chain shifting to the largest cog?
If the chain is too long, several problems may occur:
1. You maynot be able to adjust the "b" screw for optimal spacing between the large cog and pulley wheel.
2. A chain that's too long may result in the chain rubbing against the derailleur when in the smallest cog.
For this reason, we try to adjust the chain to an optimal length as shown. There are other methods to find the best chain length on the internet, but they require a little more guess work.
Regards, Tony
@@tony10speed Ok, I didn't mean to make the chain un-necessarily long, I just thought that maybe that particular chain was maybe too short. Thanks.
@@SuperOlds88 A chain that's too short may present problems when trying to shift into the largest cog. It may not shift or it may lock up if it's able to shift to the largest cog. This may be even more pronounced if you are in the large chainring and accidently shift in the rear to largest cog. Something called cross chaining. See:
czcams.com/video/_dCa-PZuN7c/video.html
Hope this answers your questions. Thanks for all your comments. We only get answers when we as questions. Regards, Tony
What is the possible thing to happen When You don't put a B Screw in the RD?? Is it still work or it can couse to damage your RD.. Hoping for your response.
Your new subscriberhere 😊
The "b-screw" adjusts the distance between the and the guide pulley. We usually adjust the b-screw while in the small chainring and largest cog. If the b-screw is not adjusted or missing, there are 2 possibilities. The guide pulley will rub against the cogs (usually the largest cog) and wear the pulley wheel very quickly as well as wearing the cog (and will also be noisy when in the largest cog). On the other hand, if the gap between the cogs and guide pulley is great you will experience poor shifting.
NOTE: Some lower end rear derailleurs and inexpensive derailleurs do not have a b-screw, leaving you with a "hit or miss" approach to setting up the derailleur. In this latter case, some suggest that the distance between the tension pulley and largest cog can be adjusted by increasing or decreasing the length of housing (and therefore cable) feeding the rear derailleur. See:
forums.mtbr.com/families-riding-kids/help-no-b-tension-screw-shimano-tourney-rear-derailluer-rd-ft30-863294.html
Some other older derailleurs have a "stop" to prevent the guide pulley from contacting the largest cog. Some have an adjustable spring.
The best thing is to consult the derailleur specification on the internet if the derailleur lacks a b-screw.
Regards, Tony
@@tony10speed hello Mr. Tony thank you very for your reponse.. Verry well explain.
i have made the jump from a 2x (16-speed) to a 1x (8-speed) i have a sora derailleur. im wondering if this tension screw might help with chain slack since i dont really have a clutch on the derailleur
More likely your chain may be too long for the setup if there's too much slack in the chain (especially if the 1 x chainring is smaller then on the previous double). Here are some videos that may help.
How to adjust chain length:
czcams.com/video/Vg2SoOOrpE8/video.html&ab_channel=GlobalCyclingNetwork
How to adjust the rear derailleur
czcams.com/video/3Mq5x7VAWhw/video.html:
All new bicycles need this (which may or maynot apply to your setup):
czcams.com/video/pMrOs3P9nn8/video.html&ab_channel=SickBiker
Finally adjust the "b" screw as in our video.
Regards, Tony
after 30 minutes of googling i FINALLY understand what the hell the B screw does
Often don't have to change the "b" screw settings when properly set. However, when changing to a different size cassette or new derailleur and on some new bikes, the "b" screw setting will enhance performance. Regards and safe cycling, Tony
What screw tightens the chain? I do not want to take a link out. Not concerned with the shifting. Trying to get rid of some of the chain slack . Thanks
If you're not concerned with shifting, I assume you have a fixed gear (single chain ring / single cog). If so, see the following video:
czcams.com/video/QuLgpvrQzcI/video.html
Otherwise, see our video on chain length:
czcams.com/video/2MbhSfHZkCI/video.html
@@tony10speed I appreciate the information. I have a 6 speed falcon system. And falcon derailleur
On Shimano Trouney for Road Bikes the B screw is a dummy it does nothing :) Took me many day to figure that out.
You'll only notice the "b" screw move the pulley wheel away from the cassette cog when in the small chainring and largest cassette cog. If that's not the case (i.e. no movement of the guide pulley and chain when turning the "b" screw while in the small chain ring and largest cassette cog), the manufacturer inserted a b screw that was too short.
If the guide pulley wheel is not hitting the largest cassette cog, I wouldn't do anything. If guide pulley wheel is hitting the largest cassette cog, you can obtain longer "b" screws (I bought a couple but I had to search the internet for them - the threading on the "b" screw is important and you can't use any hex or Phillips head screw). Regards and safe cycling, Tony
When I adjust my b screw I dont see any movement happening to the setting of the gears , I have new 11-50 high range 9 speed ,old was 11-32 . Is there a way to increase the spring pressure so the pressure maintains the gap when set , thanks in advance, thanks for the great video
Either the rear derailleur may not have the capacity to handle such a large cassette cog (or may not be able to handle the difference in number of teeth or the rear (50-11=39 + the difference in teeth of the chain rings) (check the rear derailleur specs that came with the derailleur or look on line) OR the rear derailleur hanger is not long enough (some bikes allow you to change the rear hanger to a longer one). My old 9 speed road bike could only handle up to a 11-32 in the rear because the hanger was to short. I jerry-ringed a longer rear hanger and longer b-screw and got the derailleur to work with an 11-34 but couldn't go larger due to limitations on the rear derailleur capacity. Newer bikes with new derailleurs and longer derailleur hangers can easily do what you want. Some of the newer bikes have a single (1x) front chain ring and an 11-50 rear. I'm not sure I'd use an 11-50 on my old 9 speed. Anyway, maybe it's time to treat yourself to a new bike (assuming that this is not a new bike that you are talking about) with the gearing you want. Why, because you deserve it. Good luck and regards, Tony
@@tony10speed thanks for your help,greatly appreciated.
@@tonyvaccarelli7950 hey on amazon they have derailleur extenders works great
@@nickbaker666 yeah cassette came with one and I ordered two other ones both different lengths ,found a spring pressure mod and got a new longer stronger Allen socket head cap screw for the "B" screw and combination works great with the original hanger extension, cheers
@@tony10speed I agree and have done pretty much everything you said, plus performed a internal spring mod on the derailleur and have had a great time riding my 15 year old Kona dawg, that I got for a steal and am modernizing it on the inexpensive with good quality parts and learning to wrench and adjust my own bike , having a blast ,cheers
Can cheap derailleur like tourney shift as good as yours ?
The Shimano Tourney are entry level 6/7 speed derailleurs. The preformance does not come close to the higher end models as noted in the following reviews:
www.bike-advisor.com/shimano-tourney-tx-rear-derailleur-2011/
and
www.bikeforums.net/bicycle-mechanics/1112052-shimano-tourney-parts-they-really-mediocre.html
Regards, Tony
Didn’t know I has to lift the mech all the way up to adjust it. My shifting rumbles whenever I change to small big.. b screw problem?
Several possibilities:
1. May not be enough tension on the front derailleur cable. If you notice that when in the small chainring, the cable is very loose, undo the cable pinch bolt on the front derailleur and tighten just enough to take out the slack.
2. Check that the front derailleur cage is parallel to the frame. Look from the rear to see if it lines up.
3. Is one bent or a tooth broken:
4. Have the chainrings been changed. If the chainrings are not properly aligned (i.e. the small and large rings), you will not have the "ramping" aligned properly and the chain will not move up or down the ramping in a smooth order and will make noise. If this is the case, you should check the manufacturers specs or check with your local bike shop.
Also see Calvin Jones great video on advanced front derailleur adjustments:
czcams.com/video/vcc5-ry4fA0/video.html
Let me know how you make out. Regards and safe cycling, Tony
Was your derailleur really long enough to accommodate the larger cog?
Yes. The specs on the derailleur on the 10 year old Independent Fabrication state it could accommodate a cog of 34 teeth and a total of 38T (difference between the teeth chainrings added to the difference between the largest cog and smallest cog. I was runnin a 34/46 in the front and a 11/24 in the back. I had the 34 large cog and a total was only 35T, well within the specs. But obviously it couldn't handle it.
I don't understand what the 4-6mm gap refers to. Is it the vertical distance between the top of the guide pulley and the bottom of the largest chain ring when viewed side on?
Between the guide pulley and the largest cassette cog when viewed from the side. Regards,Tony
@@tony10speed Thanks
Why do you need the extra nut for the longer B screw?
I used the nut on the bolt because the derailleur hanger was not long enough. The bolt sits just behind the hanger. Since then, I have a better solution and that is a hanger extension. See:
www.amazon.com/product-reviews/B08HDFBNZ3/ref=acr_dp_hist_4?ie=UTF8&filterByStar=four_star&reviewerType=all_reviews#reviews-filter-bar
This allows me to use the existing bolt, is cheap and works well. Regards, Tony
@@tony10speed yea I get why you used the bolt to provide further adjustment of the b screw but its already 25mm long which should have been enough if it works only. Did you use the nut to make the bolt longer than 25mm?
The extension is what people use but some say its wonky. How is it for you?
@@ns671fr The nut on the bolt sits behind the hanger (acting like a hanger extension). As to the actual hanger extension I mentioned, the inexpensive ones worked well while the Wolf Tooth did not fit well on one of the 10 speed bikes I on which I was working. That may have been due to the bike frame itself and maybe not the Wolf Tooth hanger extender. So are they "wonky?" When they fit and are installed properly, most have worked well. Regards, Tony
Nice hack!
Yes, but why does it work?
Tony Marchand Exactly, I didn’t understood why it worked. Why it worked?.
If the pulley is too close to the cassette cog, how does that damage the pulley wheel?
If the guide pulley wheel is too close to the cog, it pinches the chain and makes a grinding noise. The teeth of the cassette may hit the teeth of the guide pulley and damage the pulley wheel.
Is M3 screw used or M4
For Shimano, they are M4 x . 75 pitch. SRAM is probably the same but you should check the specs for your specific model rear derailleur on the manufacturers web site. You can buy "b" screw for a SRAM or Shimano on Amazon.
@@tony10speed can u also tell if altus 9 speed derailleur could run 11-36 teeth as the company says it can run 11-34 only max but after I run it there is some rubbing what can I do to fix it I have already max out my b screw should I use longer B screw or get alivio 9 speed derailleur which runs11-36 teeth cassette
@@tony10speed can u tell
@@tablamasters6262 One can not tell from just looking or comparing the "b" screw to those M4 or M3 you have since the pitch may be different.Your best bet is to buy the "b" screw for the specific manufacturer of your rear derailleur (Shimano, SRAM, etc.).
Great video Sir Tony! recently I changed my RD that can accomodate 11-36T cogs and a total capacity of 45T, my front chainring is 44-32-22T. I calculated the drivetrain capacity and the result is 47T that exceeds my RD capacity, is it bad? By the way sir my RD is Shimano Alivio M3100 SGS.
Does it work in all gears, especially the front 44T. If in the 44T, you might run into some problems if you accidental shift into some of the larger cassette cogs. I've not been very successful in exceeding the derailleur capacity. Setting the "b" screw and sizing the correct chain length could be tricky. Let me know how this works for you. Tony
@@tony10speed yes it is working on 44T and I can shift it to the larger cogs. My only concern is my RD sir, I might break it because I exceeded its total capacity even if it is a long cage RD, but thank you sir! Godbless.
@@earvinvillanueva3839 The only place you may run into a problem is that when you're in the large chain ring and accidently shift to the largest cog, the chain/derailleur may lock up. Test it out. If it doesn't, your OK. Let me know. Thanks, Tony
@@tony10speed i test it out sir, i can shift it to the large cogs and large chainring with no problems, and my RD bends like the one on your video. Do you think sir that it is okay? I'll just avoid cross chaining when riding.
@@earvinvillanueva3839 I'm surprised you got it to work. Also check the "b" screw for best performance since exceeding the range for the RD often does not allow the "b" screw to contact the rear hanger. The gap between the tension pulley/chain may also be greater then 2-3 mm effecting shifting performance. See:
czcams.com/video/UXnLJpTVFJ0/video.html&ab_channel=TonyMarchand
Anyway, if all works well, you should be find. Regards, Tony
I've just ordered a derailleur and it's come without the plate between the bolt and derailleur. Is this necessary?
Not sure I can know this derailleur. What is the make and model?
@@tony10speed it's some Chinese generic sram one, ltwoo. Nothing wrong with the derailleur only that there is no b plate on it. Can I just rest the b screw on the hangar notch instead?
Yes. On many bikes, the "b" screw sits on the hanger notch. The hanger is often a little longer then older model bicycles and is also removable in case it gets damaged or bent. On older bikes, you can add a hanger extender which has it's own notch and allows you to run larger cassettes (provided your rear derailleur can handle it). Thanks for the comment. Regards, Tony
I went from a 12-28 to a brand new 11-28 cassette and there is one gear in the middle of the cassette that I cannot get it to shift to smoothly or consistently. What’s the chance that screwing in the b-screw would resolve this?
I don't think it's the "b" screw. You'll need to re-tune your rear derailleur when you switch cassettes. Here are some questions I have:
Check the chain for wear. Check the cog on the new cassette that's causing problems for manufacturers defects such as a bent or broken cassette tooth.
Is the number of cogs on the new cassette the same as the old (i.e., same speed 9,10,11 or 12)? Is the manufacturer of the cassette different (what are the manufactures of the old and new)? Shimano and SRAM are interchangeable but some other brands may not work as smoothly.
Is the freehub alloy and has it been worn (teeth like marks in the freehub suggesting increase wear)?
Finally, have you torqued the cassette. See:
czcams.com/video/qVzWQuHPz50/video.html&ab_channel=TonyMarchand
Let me know. Regards, Tony
Hi@@tony10speed. Thanks for your reply. I am working with new Shimano 105 shifters, new 105 derailleur, new chain, new housing and cable, and the cassette is brand new too. All 10spd. My indexing is fine except when I try to go from the 14t cog to the 15t cog. I have to shift again, and it just skips past the 15t cog. I even tried swapping in the 15t cog from the old cassette thinking it may be a lemon cog on the new cassette, but the behavior was the same. I watched your torque video, and I am torqued properly, and the freehub looks fine, without excessive wear.
The new cassette is a SRAM PG1050. The taller cogs are all held together using a spider, and then the smaller cogs use plastic spacers, then the smallest are spaced with metal on the side of the cog. The only thing I can think of now is that the spacers are improperly sized just enough that they create a problem at this specific cog.
@@theMRkevinB Check that you don't have a bent derailleur hanger. See:
czcams.com/video/qHK6jQizIdc/video.html&ab_channel=TonyMarchand
Make sure you didn't forget a spacer that is placed on the freehub before you put on the cassette. The spacer allows for the freehub to accept a 9, 10 or 11 speed cassette. Other possible problems include a kinked cable (inside the shifter when the cable was installed), or a bent tooth or burr on the 14 cog of your new cassette not allowing it to shift properly to the 15 cog (making you shift twice which move the chain to the 16th cog). On a bike stand, slowly turn the crank while in the 14th cog and shift while watching the chain and cog teeth. See if you can notice where the problem lies. I have had a similar problem with one of the larger cogs that I traced to a bad shifter. Finally, take it down to your local bike shop and have them take a look. Let me know what you find out. Regards, Tony
What is the right screw size of the derailleur?
Good question. Depends on the derailleur manufacturer, road or mtb, and whether you're talking about the "b" screw or limiting screws. The screw itself depends on: Length, thickness, thread pitch, thread form. Most "b" screws are standard M4 threads. In the video, I was replacing the "b" screw on a Shimano Deore derailleur which accommodates a Wolf Tooth Components M4 25mm B-Screw (available from Amazon or Home Depot). Note: If the "b" screw is too long, it may go beyond the derailleur hanger, in which case you'll need a longer hanger (if it's a replaceable type) on a Wolf hanger extension. You can also look up the specs for the "b" screw on the internet or contact the manufacturer or local bike store. Regards, Tony
Is the 4-6 mm distance critical?
No, the distance is not critical. Long as your cassette cog is not to close to the guide pulley to pinch the chain and make a grinding noise which is bothersome and may damage the guide pulley.
@Tony Marchand can u also tell if altus 9 speed derailleur could run 11-36 teeth as the company says it can run 11-34 only max but after I run it there is some rubbing what can I do to fix it I have already max out my b screw should I use longer B screw or get alivio 9 speed derailleur which runs11-36 teeth cassette
I've done exactly what you want by using a "hanger extension" which costs about $5. Be sure to get an extender that is made for the speed of your bike. The inexpensive ones will work on 9 speed and less. For 10 or 11 speed, the hanger should be specific for that speed. See:
czcams.com/video/eXemxzz1ctU/video.html&ab_channel=PedalPower
Regards, Tony
@@tony10speed I live in India so extender is not available here any other option
@@tablamasters6262 Try Amazon on line:
www.amazon.com/dp/B0852WGR61/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=ce9e7edbecbc1f86fb98304e855848ef&hsa_cr_id=6642938180301&pd_rd_plhdr=t&pd_rd_r=83a9fa9c-b83e-4ba3-9657-0388c3fe588f&pd_rd_w=sXBBa&pd_rd_wg=n8T3j&ref_=sbx_be_s_sparkle_mcd_asin_1_img
or something similar. Otherwise you have to go with a long cage derailleur.
@@tony10speed I think I need to longer my b screw if that's not gonna work I am gonna leave it
@@tablamasters6262 You can buy a longer "b" screw but it may not contact the hanger as you tighten it. It will probably go behind the rear derailleur hanger. If you can place the right size nut on the longer "b" screw after insert it, it may give you enough push off the back of the hanger to work. I've done this with good results.
Regards, Tony
NO NO.
Your "B" screw is in all the way. How can you adjust that?
We are showing you what you must do to acheive an adequate distance between the pulley wheel and largest cog. Our needs, as stated in the video, required us to turn the "b" screw all the way in to achieve the 2-4mm between the pulley wheel and cassette cog.