My MTB Frame Needs a Disc Brake Tab and a Seat Stay Bridge!
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- čas přidán 10. 08. 2019
- With the main tubes of the MTB frame build completed, we're moving onto all the random other stuff: disc brake tab, seat stay bridge, water bottle bosses, and cable guides (a.k.a. braze-ons). This video covers the disc brake tab and seat stay bridge.
For this bike, I'm using an ISO disc brake tab, believe it or not. In the video I explain why I chose to use the ISO standard instead of post mount or flat mount. (Partly it's just because I already have a good tool for adding ISO brake tabs; it's Anvil Bikeworks' lSO Rear Disc Brake Tab Fixture, aka “Feng Shui.")
Here's a PDF on disc brake mounting specifications for the international standard (IS): www.magura.com/media/1997/is_...
I show a bunch of the process of grinding the disc brake tab to fit up against the seat stay. First I was using a disc brake tab from Nova Cycle Supply. Then I botched that one, so I used one from Paragon Machine Works. I was using my new Metabo angle grinder, and I was really having too much fun removing the material.
Here's the Metabo angle grinder if you're interested in checking that out: www.amazon.com/Metabo-WP9-115...
Toward the end of the video, I miter the seat stay bridge. For this, I use a DIY framebuilding tool based on a design by Sputnik Tool. I really think this setup is slick for mitering the seat stay bridge.
Here's my interview with Carl Strong (Strong Frames and Pursuit Cycles) I mentioned, from the Shutup and Build Bikes Podcast: cobraframebuilding.com/podcas...
Here is the playlist of the whole Hardtail Mountain Bike Frame Build-I'll keep adding to it as we go: • Building a Hardtail MT...
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Solution to that tab fitting is to cut a card stock (business card or so) template of the part, fit it by bending, and then mark back the result. Model making trick. You could even trace out and cut a thin version of that positioning template - all we need is a good picture~ (sorry, boys.) There could (should) be a cardboard or plastic template or printout included with the part.
man! great channel. I like the rhythm and enthusiasm of your videos. I especially appreciate the philosophy of that specific playlist and behind this MTB build; it's in between DIY and professional work. Thx ! cheers
Another excellent video. I really admire your willingness to make mistakes and include them in the video. No giant ego driving your content...just great info.
A different approach that you might consider is that the two tabs can be totally separate like two tombstones. Then each tab can be ground in separately. And its super easy to make your own out of solid plate.
Hello ..bravo , all explanation about tool and method are clear !!!👍
You're ace man, thanks for doing these videos!
Nice that you included a mistake for us to avoid. Thanks for your patience, too! Keep up the great attitude!
I just did a retro disc tab mount on my 1995 hardrock. Used a disc wheel as the fixture and tacked the iso tab in place. Pretty accurate. Kinda clumsy, though. I added a support in the triangle as you did. I saw that Incepi makes a nice little fixture that works on front and back. Your vids are very helpful. Thanks
No Prob! Thanks for watchin!
I love how you’re trying to get close to what you’re getting with this adapter or bracket for the disc brakes. maybe mock up with cardboard or paper trace it out with what your working with and cut the cardboard or paper use it as your base . and or if you’re doing a lot of cutting or grinding. maybe a Deburring wheel would help than a grinding wheel. Sorry it’s a the aerospace mindset I have , when I worked on the shop floor in cutting deburring, and polishing parts 😀 and using Calipers and measuring tools. I’ve used that knowledge in DIY projects with scooters and bikes that I’ve learned working in Aerospace/ Power field for 14yrs.But I like what you’re doing and it’s very informative 👍🏼
This channel deserves millions of views!
Thanks!
killing it joe.
I used a OLD Hayes Mechanical Disc Brake and a OLD HUB mounted in the Frame and Applied to a Disc Rotor.and Got the Local Welder to TIG Weld it to the Aluminium Frame .
3:18 i believe that iso mount is better than post mount, because if you strip the threads you can just buy a new adaptor , but post mount makes the repair much more difficult and expensive. either buy a new frame or a helicoil repair, which costs around 70 dollars or more if you don't do it yourself.
Thanks for sharing Dude! 🤟🏻
Awesome videos and podcasts Joe! Cobra Frames is the best way to start the week. I have been working on some frames along side this series and it seems like everytime I encounter an impasse you drop a video related to what I am stuck on. I was cursing at a seat stay bridge last week as it was just not playing nicely when it came to welding it in. It is tough to make those one or two puddles you need to wrap those acute sections. I think it was Walt saying on MTBR that he only puts in seat stay bridges if the customer asks for it, or for road brakes.
I'm glad you like the videos and podcasts!
I quite like the grinder for rough cuts because you don't have to clamp the tube as tight as for a hacksaw (can actually just hold it in your other hand). A worn out flap disk is pretty good for mitring and a bird's nest wheel will clean off that black stuff (which isn't really mill scale but people call it that) without sanding down the actual metal.
Would be good to have a bunch of grinders set up and ready to go.
Miami Vise! Awesome
Get a 80grit flap disc for precision material removal with a grinder.
Also be careful with sparks aimed at electrical boxes
I get that this video was more about playing with a new tool, the angle grinder, than figuring out the best way to shape the brake tab.
But, I always seem to be interested in the geometry of these practical problems.
Since the brake tab is basically a plane, and the stay is non-tapered, i.e. a cylinder shape, the intersection of the two will form an ellipse. Actually even if this were a straight tapered stay, the intersection would also be an ellipse, and the methods below would work.
Now as I watched your video again, I see that the far part of the tab closest to the axle needed to be bent because it extended beyond the stay. In that case, knowing the plane intersection curve is of no use, but knowing the ellipse intersection is still of use where the plane of the tab was not bent, and intersects the stay.
If you can estimate the major and minor axis of the ellipse, and draw it using the string method, or some other way, then that would give a great 1st approximation to the intersection curve to grind to. The major axis length could be estimated by using a straight edge to draw the intersection curve onto the stay, then measuring between the two most distant points with a caliper. (easy to say) The minor axis is measured in the same plane, half way between the end points, and at right angles to the major axis.
This may not be perfect but it's a good start. The next step will produce a cardboard template with the ellipse placed in the correct location.
First, cut out the interior of the ellipse and also the lower half, so as to be able to place over the stay. Also make a rough proxy to the tab with flat cardboard and bolt holes and short enough so as to not touch the stay, but be a good place to , tape the cutout ellipse to. Tape the ellipse part on the cardboard part to complete the template. Finally, transfer the curve over to the tab blank, and start removing steel.
Of course the (unbent) brake tab is not a single plane, but a front and back plane, So if you wanted to get the front and back curves, this would work just the same.
Frankly with your skills, If you already have the bike in a model, I would model the the plane positioning aspects of you fancy alignment tool, so in the future you could let the CAD package determine the shape of the intersection in proper alignment.
Someday soon I hope to start building my own bikes, and your channel will definitely be a place to hang out.
I'm sure someone mentioned already, but it's damn near mandatory to wear a face shield while grinding. Glasses work just fine... Until they don't. :( Otherwise, great video. Keep up the good work!
@Steve Hartig
Them’s some serious Deirdre Barlow’s he’s got going there 👍
Great video! Wondering if you recommend a frame builder that can convert my 1996 steel Yeti frame from V-brakes to rear disc brakes? Anyone's help would be greatly appreciated.
Hello, nice video btw. Does adjusting seat stay bridge of a vintage bike to fit 29er wheelset worth it or removing it completely is even better? Thank you.
If that triangle brake brace is good enough for Litespeed then it is good enough for me.
I would like to see how to adapt a regular rear hub to disc...
That frame looks very much like SRAM UNI put on a Rocky Mountain.. tange frame.. exactly the bike I'm looking to do this to
PDF file is missing, will you please give me another link.
I have been using a Brake Therapy adapter for the rear of my 95 GT RTS. I really need to weld a tab onto the rear triangle (cromo), I just wish I could find the tabs somewhere that they don't cost more than the bike.
Paragon machine works has them for about $10. You can make one from scrap if you have time on your hands. The only expensive part is if you’re paying someone to do it for you.
Hallo. Thnx for the vid, cool stuff.
Can you please write the names of the companies where I can order frame building parts (like your brake mounts etc)
Joe, this is an excellent video, i was particularly interested in how disc tab were shaped and sized, you answered a lot of questions i had. Congratulations but...
Please.
Wear safety glasses.
Please. Yoûre young, you’re wild, i like it, keep going, that’s fine but just listen a bit: those safety items have a reallly good reason to exist. Îve seen horrible stuff, i don’t want it to happen to you.
And along those lines, do not grind with the side of a cutoff wheel!!!
So you have a neat gizmo that fits the tab exactly where you want it , so if you did not have that gizmo what would you do?
Hey! Love the videos but haven't found the podcast on spotify. Is it up on that platform yet?
Sorry, I've been slow to figure that out. It's on my website, which easily syncs to apple but I haven't made the effort to get it more broadly distributed.
I know the Metabo is nice an all but I think for your use case you'd be better to return it and use the money to buy as many $24 blue harbor freight grinders as you can, build one Werth a cutoff wheel, one with a knotted wire wheel, one with a cup wire wheel, and then build then with 60,120,and 220 (400 if they sell those) flap disks. For the same money you'll save a ton of time, the hf don't cut any slower on the light work you do. the first thing to die on grinders is the pin to ring gear interface for changing disks regardless of brand anyways, unless you're a shaved aped and lean on the thing till it melts down in your hand.
That's a good point generally, but I just don't do a ton of that kind of fab work. I got by for years without any angle grinders in the shop and they're so messy I don't particularly want to use them that often. The metabo is super nice and I like it, but if I ever find myself using it often I probably will get some more grinders with dedicated discs for the various things they get used for. Growing up, my dad had a farm machinery repair shop with probably 6 or more different angle grinders at the welding table and I know how useful that can be for that kind of rough, "just gettin it done" MIG welding and fab work.
GOLD! I reel like I have finally struck paydirte. I have an old Schwinn Homegrown ('95 or '96) in beautiful bass boat blue that has disc brake bracket built in. I think it has the old Hayes direct mount. I bought some cheaper tektro brakes to put on it and of course they don't fit so I'm still on rim V brakes.
Anyhow now I have a clue what to look for.
BTW, the bike is currently setup with a greet bananna seat for neighborhood cruise duty. Before the Bannanna seat it has had hundreds of miles in the woods and trails of NC and AL, lots of history.
Is there a conversion bracket from Hayes to ISO? I have a TIG welder but I don't want to ruin that beautiful frame.
Anyway looking forward to more of your vids. What's your take on penny farthings BTW?
Before the Bannanna seat it has had hundreds of miles in the woods and trails of NC and AL, lots of history.
ALWAYS BUILD A TEMPLATE? - out of card stock - you just shape it by bending, and cut when perfect. This one is easy ~ and then transfer that shape.
Notice the top cross bar tube meets the seat post tube the two rear down tubes shouldn't be above the cross bar tube should be on equal centers to each other.🐤🔔😎
The only "Rule" for the tops of seat stays is that they join the seat tube at an area that is either reinforced externally or is backed internally by the seat post...all to avoid collapsing the seat tube in a big hit.
Everything else is personal preference/other logical considerations such as standover height etc.
can you put the pdf link up again?
Does the seatstay tube diameter need to be certain thickness for welding disc mounts?
There are a lot of variables at play. I don’t have a specific number but it’s something to be thinking about. Disc brakes stress frames more than a lot of other components.
yuel see the old man of the mtn
wrong rearend for my junker
have fun
Anyone know what the round dropouts are called?
Using a cut off wheel on a grinder adds risk and doesn't allow you to sneak up on a shape, if your within 1 mm or so and weld well then there's no drama. I would be surprised if you would bend the rear triangle as F = d dt of MV, given the lack of weight over the rear wheel esp' during braking, weight shifts forward, minimising friction between tyre and road and a 140 - 160 mm disk with 2 pot calliper would not exceed the rear triangle frame strength. Enjoy. As we both know hydraulic brakes are way better, not so much due to outright braking performance, that's determined by weight and friction, its the feel and smooth progression of the brake. Ta.
How would you recommend getting the disk tab jig now that anvil is closed
Lichen precision sells a disc brake holder
I would love to have your skill real interesting stuff thank you.
Well I'd only need his machines. The rest is fun to learn!
I think it would have been far more sensible to make a cardboard template ( CAD - cardboard aided design) rather than just scrap parts?
But flat mount just looks so sexy.
U CALL THIS A HACK - The other way to set your disk brake mounting bracket points is to add your wheel with disk TO THE FRAME, wrap the calliper around it with bracket boltED on, add a few mm clearance (radially), mark and weld, simples my friend.
Subscribed, Cool channel and all, but a face mask, well, will save your face, griding with a cutoff wheel you're asking for it to explode off the grinder and send shrapnel at you. Use a grinding wheel or a flap disc for more precision. Also, cardboard or foam board templates will make this process 10 x easier rather than guessing and cutting all that material and ruining a part. But in the end, who cares how you do it as long as it works. lol
Where’s your base i want my litespeed frame to be a disc brakes
Question ?
the 2019 Frames Eleminated the Seat Stay Bridge ? WHY
Good video by the way
Man use dust mask or at least work shop filter, you can finish much more faster caliper holder on frame and on fake hub mount, no point to go 5m away from frame.
question ! how do you do the pinch slits thru the frame tubing / and QR tube for the quick releases at the seat post- and other places on the frame if needed. i use a lot of those in my kick scooter dog pulling systems i make ! www.dogpoweredscooter.com
I honestly haven't seen anyone worse with tooks and more slopoy than you man!
I mean..are you sure you up for this kind of business?????
Where is your face shield??
You’ve never seen a grinding disk blow up have you?
Dennis Young a dremel sized one is good for a dremel. You’re using a angle grinder. You need one that is good for that. I’ve seen a guy get fucked out pretty bad using a angle grinder when the disk blew up.
Do a google image search. You’ll understand
Anvil bikes is going out of business.
Yeah, the end of an era.
Although to be clear, he's not "going out of business" by a long shot. He's just retiring.
@@cobraframebuilding This news just broke a little piece of my heart. On the bright side, our Anvil fixtures are now Collectors Items.
I got the impression that some of Don's tooling designs are going to be made by Paragon? Maybe just wishful thinking on my end, as I neglected to purchase the feng shui or post punk jigs.
He said paragon is going to make dummy axles. He didn't mention anything else. He said he is retiring. No more bike related activity. Sputnik makes very good stuff.
Mate, you're a vandal, but well done nevertheless!
You do good work, you're just talking too much !! just put it together!
Dude! Use gloves! You don't know how angry an angle grinder can get. And then lose the cutoff wheel after you are close and switch to a grinding wheel. And then to a flap wheel. It's like sandpaper. Coarse grit to fine grit. Get a bench grinder.
I think he fucked up at the beginning
Should have been more artistic with the brace.
, , ,, ,, , to mch talking.....