Disc Brakes on a 90's Bike - Converting the Frame to Hydraulic Brakes 

Thank you!

Couldn’t agree more 🎉

Wow! You are exactly right. I'm not quite sure how I missed that. Thank you!

I’m excited for the Kona build. I got to buy a new rotary table just for that project. It’s going to be awesome.

I didn't even think about that. Hmmm. Next project, right?!

Ha! That's where I learned it, too.

Great point!

Thank you kindly!

Appreciate it, thank you. Yep, you're spot on. This was a disc fork. I did adapt it for thru axles, but native disc.

Actually, that gives me an idea. What if I'd model the original cantilever brakes and see what forces those applied to the stays under the same conditions? It could serve as a good baseline. The only other idea I have is strain gauges on the rear stays but that is sure expensive and I'm 100% we'll get the same results.

@@RobertAdairWorkshop @RobertAdairWorkshop it surely would be interesting to reverse engineer the original design, just to put it into perspective with yours. But for rim brakes, the braking force might not even be the most significant one. For such thin tube I would definitely also consider the buckling load from your weight but and also from the forces from wheel into axle. Using strain gauges could be a fun project that I thought about myself. You can get cheap ones from china including some arduino amplifier modules. But proper installation, processing the results and calibration could be frustrating. If it was to me, I would simply lock the brake, try to turn the wheel to simulate the braking torque and observe closely the bending of the tube. Btw how did you measure the thickness of the stay tube for your FEM model? Is it the same along the length of the tube? And also what UTS of the material do you use in the FEM?

I mig welded it because I don’t know how to braze. I totally got ya!

I did discs on an aluminum 1998 Stumpjumper last year. It was actually easier to do but you're kind of taking your life into your own hands with the brazing. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vD1pH86wCrU.html

I think brazing it is probably the frame builders “correct way” to do it. I just never learned to braze so I’m sticking with what I know.

Totally get it! With the FEA and exceptional thoroughness of your video I assumed it was a strength calculation. I wish I was setup for welding but brazing is super simple (except for the acetylene shortage ha). Getting filler rod of the right type is harder the torching metal until it starts wicking filler in. Great video again and glad it popped up in my feed. Newly subscribed!

The 984N I calculated is for a situation worse-than a panic stop where there is no slippage. A panic stop would be less than that 984. The calculates FOS does cover max braking.

No, sadly, this one is a bit too old to look at fatigue stresses. I’d like to have a modern version but the software is ridiculously expensive for one license. Maybe if I make it big on RU-vid, I’ll celebrate with software.

Amazon. Here's the basic link -> www.amazon.com/gp/product/B07DND33HV I had to round the bottom of each with some sandpaper wrapped around a dowel, to get them to sit flat on the frame. I didn't show that in the video.

@@RobertAdairWorkshop Awesome, thanks! Ive welded tabs on an old schwinn and I'm excited to put these to use too

It’s a Hobbyaire system I bought back in the early 2k’s to paint a 300zx. Still works great. Draws from filtered shop air.

700c x 40. I talked about it in the original build video. That gives 8mm at the stay bridge. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WDkYQHh_scU.htmlsi=dsn5uc-Sn0hriI5d&t=1179

@@RobertAdairWorkshop oh. Yes thanks. So 40c on a wide 27internal rim would be the frames max. That would probably bulge it out to 41 or almost 42. Ever thought about putting in some 42c ? Or would that be bad for your type of riding in muddy areas?

Probably the noise reduction I use to try and cut down on the background noise from my workshop heater. I didn't notice til you mentioned it. I'll see what I can do for the next one.

Very impressive. I wish there was an easy way to properly face brake mounts and tabs. For the home mechanic the tools are out of reach.

You might be if you live in Denver, Colorado.

@@RobertAdairWorkshop Rural Maine for me! Thanks for the videos, keep up the good work 👍

I don't think you watched the video. Look at 8:52. I talk about, just that, for at least 5 minutes.