Brake on Coker

I have bought Magura HS33 for my GB Coker. When I test them either the wheel or the frame flexes when us a bit of power on the Coker.
Do you guys have a large distance between your brake pads an the wheel to avoid this? Or what should I do to remove the flexing (the wheel is pretty tights see under)?

I had my wheel trued last year, so the spokes are pretty thight.

Airfoil rim, Wide Coker hub, GB36 Coker frame


Go away snow

A combination of more tension on the spokes and more distance between the pads and the rim.

The wheel flex is one reason why Dave Stockton came up with his Strongest Coker Wheel. In part to eliminate wheel flex that is noticeable when using a brake.

Get the tension on the spokes as high as the wheel builder reasonably can. I’m not sure how high you can go with the stock Coker spokes. Dave Stockton uses the custom cut stainless steel spokes from Tom Miller (The Unicycle Factory).

The other thing to check is to make sure the bearing clamps on the GB4 frame are tight enough. They only have a lip on one side of the clamp. If the bearing clamps are too loose the frame can slide on the bearing a bit. So tighten them up, but not too tight.

I have a GB4, Airfoil rim, Tom Miller spokes, UDC wide hub, and a Magura brake. The wheel was built by a local rider and has a fair amount of tension in the spokes. It all works well and the brake pads don’t rub the rim. The trick is a good wheel build with lots of tension in the spokes.

proper spoke tension

John: I have been searching the threads on coker wheel building and lots of folks talk about higher spoke tension, bu I never hear anyone say how tight? If I knew this number, I’d be able to tell my LBS wheel builder just how much they can tighten things down without worrying about breaking anything. Do you or others out there have a recommendation?

The wheel I want to build would use the UDC extra wide hub, Airfoil rim and the ss 14 ga spokes (4 cross pattern) that UDC is now selling.

So you’re saying tighter bearing clamps will help? :stuck_out_tongue:

Tight enough that the frame doesn’t slide on the bearings under heavy pedaling load or Coker XC muni use.

I only mention that because I’ve had my brake rub on my Coker before and the cause was because one of the bearing clamps had gotten too loose.

I don’t know any numbers for tension. The process seems to be build the wheel to a tension at which the wheel builder believes the wheel is stiff enough. Ride it around. If it flexes too much then take it back to the wheel builder for more tension. Repeat until it works well.

The stainless steel spokes also seem to stretch a bit after riding. Or maybe that stretch is just due to spoke windup that releases after the wheel has been ridden. In any event you’ll likely have to take the wheel back to the wheel builder for a fixup especially if it is their first Coker Airfoil wheel.

My Coker wheel was built by a local Seattle rider, unisk8r. It has been good. He has built several Coker Airfoil wheels.


Thanks John. I appreciate the help.