I use my Coker mostly on paved roads and have been thinking about mounting a calliper brake like the 'Shimano Sora' (http://tinyurl.com/9mkg9).
Is this a good idea? A calliper brake is small and easy to mount but can it be used as drag brake as well? And is a 49 mm reach enough for the brake to fit around the voluminous Coker tyre?
*I doubt you'll be able to fit a caliper brake on a Coker, even if you pried the lever arms apart. Get a V-brake instead, or a Magura rim brake.
I think drag brakes have more to do with the lever than the brake itself. *
Calliper brakes would be easier to mount than V-brakes and Maguras because they do not require any mounts to be brazed.
For a drag brake to work properly the lever must have some sort of easy adjustment screw but I was thinking more in terms of calliper brakes not being able to be adjusted for toe-in. In other words the brake pads reach the rim squarely which can cause them to squeal.
Hasn't anybody here tried calliper brakes on a Coker?
I have an old BMX caliper brake on my coker, it works fine. I don't think the caliper you're looking at is big enough to clear the coker tyre.
I know a few riders who are running stock coker frames with caliper brakes because they're much easier to mount then maguras or V brakes, and they're not so sensitive to the straightness (or not) of the wheel. They're never going to be as powerful as maguras or v brakes, but as a drag brake they work fine.
