Erik_A

I am trying to find a product that I know exists but I can't find. It is a Cantilever Post Adapter than screws into the original post holes and allows you to move them up about a 1/2". I want to modift my 650B frame to run 700C road wheels with 28c tires. The frame is a Velo Orange Polyvalent designed for 650B large volume tires.

I have seen these adapters for about $25 online (thought they were Paul Comp. or Problem Solvers), but was wrong. Does anyone have a link to these?

the frame: Polyvalent MK3 Frame and Fork (which I want to be able to adapt back to large volume 650B in the future).

Amesja

Bdop has an offset brake pad holder that will do the same thing for a wheel conversion when you just need to move it a few mm. I've never tried them but they should work fairly well. I would imagine that it would complicate setting the pads on the rim since you couldn't just use the caliper to set them down on the rim as you tighten them. They would twist off-center and rotate the pads. But it would be doable.

Erik_A

Thanks, I am trying to use cantilever brakes though - so those won't work well..

Amesja

Oh, I also see that you want to go to from 650b to 700c. I misread and though you wanted to go between 27 to 700c.

Most newer-style cantilevers don't use post-type brake pads any more. That's pretty old-school. Those pad would work perfectly fine on modern cantis. I'm using Dura padholders on my Avid Shorties. They work great.

Wilfred Laurier

Good luck getting your mod to work... but what are you hoping to accomplish?

Erik_A

To be able to go back and forth between 650b with 50c tires and 700c with 28mm tires on the frame (designed for 650b wheels and large volume).

Erik_A

Besides Paul and problem solvers, who else makes old-school custom components in the same vein?

Wilfred Laurier

I understand that you want to fit 700c wheels, but what difference are you hoping to realize in actual riding? Why not get a second set of 650b wheels with narrower tires?

Erik_A

The frame would ride too low. I run 180mm cranks. The diameter of 650c wheels with 50c tires is almost identical to 700c with 28c tires.

Wilfred Laurier

I also ride 180mm cranks and ride a touring bike that is most comfortable on 38mm tires (as VO says your frame is), but it has no problem on 28 mm tires.

Anyhoo, post pics when you are done. I bet it will be killer!

Andrew R Stewart 

I'd be a bit concerned with a boss adapter. Having not seen them I'd want to feel completely confident that they would handle the forces of braking properly.

But would the frame allow for caliper brakes when 700c was in use? Really the simplest choice is what Wilfred said. Andy.

nfmisso

Erik, this is what you are looking for: ELEVN RACING | Brake Adaptators

See: https://www.bikeforums.net/classic-vi...onversion.html for more info and sources.

They are beefy and will have no trouble with braking loads.

Erik_A

Thanks - that is what I need!

Darth Lefty 

What an interesting product. A 700c vs a 650b rim is 19 mm, a 650b vs 26er is 12.5 mm, so this pretty well splits the difference allowing you to try 650b from either direction.

I wonder why they made it out of aluminum.

If you were starting from scratch I still think the disk frame idea is better.

nfmisso

A LOT less expensive to machine, less expensive to provide a very nice hard finish on (hard black anodize), and less expensive to laser mark the graphics. It is a very thick part, so b*h cubed comes in to play, provide plenty of strength.