Is there such thing as canti to u brake adapters?

[FluffyChicken]

 

[Woz]

Mavic had an adapter to mount road calipers. I don't remember if it was meant for 26" or 700c. Did they do a u brake adapter?

Thought about this too. It was to put 700c road wheels in a 26c, and will thus higher the canti bosses.

Question is, would it higher them to be in the ball park for a U-brake?

Sounds like a bit of a fuss and compromise though. Understood these adapters are getting rare to find too.

I think if I wanted to try something like this on the cheap, it would be any old frame or forks from the tip for canti-bosses, and try to re-use them by welding them to the chain stay - leaving the ones on the seat stays well alone in case it all ends in tears.

 

[dbwheels]

Question is, would it higher them to be in the ball park for a U-brake?

No. Using the bead seat diameters gives you (700c) 622mm - (26") 559mm = 63mm/2 = 31.5mm radial difference in the boss location. You would need ±58mm.

 

[Woz]

No. Using the bead seat diameters gives you (700c) 622mm - (26") 559mm = 63mm/2 = 31.5mm radial difference in the boss location. You would need ±58mm.

- and maths doesn't lie. It's way off. probably off in the horizontal axis too since they were intended for (narrower) road wheels.

 

[Mod-Master]

Now I remember why I didn't do it.
Look at the attached drawing. Remember that I wanted to go from U Brake to canti...it would have meant that the canti bosses hung out in the wind, unsupported; too much resonance and chatter.
If you are going from canti to Ubrake, it might work if you could add a 3rd attachment point on the brake bridge (if there is one). Make the plate out of 1/4" alloy. Could work, I guess.

View attachment 718845

I’m a bit confused why are the canti bosses in a slot shape? Are the canti bosses 75 or 85 mm apart?

 

[dbwheels]

I’m a bit confused why are the canti bosses in a slot shape? Are the canti bosses 75 or 85 mm apart?

I just put together a quick drawing based on the dimensions from the links in the post above that one.
Cantilever bosses are usually located in that range of 75-85mm c/c. If one were to build a custom adapter plate, the centres could be machined exactly as specified, otherwise it may be beneficial to slot the mounting holes to provide some room for error.

 

[Mod-Master]

I just put together a quick drawing based on the dimensions from the links in the post above that one.
Cantilever bosses are usually located in that range of 75-85mm c/c. If one were to build a custom adapter plate, the centres could be machined exactly as specified, otherwise it may be beneficial to slot the mounting holes to provide some room for error.

Got it

 

[FluffyChicken]

If you look at the U4 booster I linked too. for the conversion you put it flat to the frame/fork, then bolt it down on the boss and top hole in fork etc.
You then mount the bosses on in one of the two smaller bolt holes halfway down. I think it is the top one of the two. You can the fit a U-brake/Cam as you wish.

 

[Mod-Master]

I'm going to use the measurements that @dbwheels linked so kindly and going to model an adapter a bit like the Mavic 700c one. if it all works out then I'll CNC it and fit a u brake. if it works well then I shall place it upon the all deserving kona.

I could even mount a cable stop at the top

 

[FluffyChicken]

Just remember U-Brakes are for road duty or dry dusty weather.
Anything that involves, leaves, long grass, mud or sticks is ... interesting.
Mounting adaptors, like the U4, make it ever more fun to ride in mud and leaves...