GIOS : One of its kind !

[bdu...@gmail.com]

here is a conversion to 650B , but from a 26 MTB !

I find these interesting because the frames allow for fatter tyres and my old bones like it.

I wanted to  find an early MTB with an horizontal top tube.

In France, it is actually a bit tricky as MTB use and progress was later than in the US of A

I managed finally to find one and with a prestigious tag : GIOS

But it is primarily a road bike specialist and when the bike arrived , it showed :-(

I don't even dare to mention the weight of the frame/fork.....

I had planned to pimp it with a nice bullmoose Nitto  and some Shimano M732 parts, but clearly the frame is not worthy of it  - more or less gas pipe ! - so I did a more inconspicuous build ( Shimano Mountain LX mostly the original derailleurs and  bar with commands).

The nice parts are actually the wheels - Shimano 600 hubs on rare Ambrosio 650 rims built for the occasion.

I show it actually mostly for the "how to find a solution for the brakes on 650B wheels for a 26 frame" ?

I have already shown some conversions with V brakes but for BMX such as the Paul BMX  brakes , or some "chinese" models which allow for a large range of brake shoe height.

But if you want to keep cantilevers with central pull, then not so easy.

Well , Tektro 720 cantis are your friend !  I had read it could work but also that they could be insufficient. So I tried and well on my frame it works.

Bruno ( Paris) 

Pics

[Brad]

What did you do to make the fenders connect at the fork and the brake bridge?

I have a project with big gaps and I am looking for proven solutions. 

[bdu...@gmail.com]

Hi

Thanks to my abundant stash of "ironmongery ", I manage to find washers of different sizes or shapes -  specifically the  ones which are curved on one side - concave or convex - or "long ones"  

Fork fixture is from the inside with descending bolt and I added 2 rubber big washers to fill the gap a bit 

Hope this helps , but clearly neat fender mounting is a "chore" ! takes time and specific parts ........

see pics - two are from another build on a 650B (titanium frame !)

Bruno - PARIS ( the French one)

[Alex I]

For the Soma Champs Elysses road fork, the drop to a 650b wheel and fender is pretty high (DC 750s at close to bottom of slot as you can see). I used a standard daruma bolt, an M6 coupling, and a M6 bolt from inside the fender to make the connection. The underside of the crown was sloped in the middle at the steer tube, so I took the big daruma washer and clamped it in the vise, then bent it until the profile matched the fork underside more or less, otherwise it kept slipping back and forth. A bit of careful adjustment and tightening between the fender screw and coupling got it centered and tight. Held up fine so far, but not too many miles. I was hoping to bend the washer more outside the coupling diameter but failed as you can probably tell, it doesn't have a ton of contact area (could possibly file down the ridges on the top side). I followed Anton's guide to get the fender dimpled there so the bolt can be nice and vertical.