Bicycle Mechanics - U brakes

i have an old dyno air frame that i want to put the 990 u brakes on. i already know that i can buy the 990 mount plate for a fork that doesn't have the 990 mounts in the front, but if i want to use the u brake in the rear which 990 brake should i use with the plate, the front or the rear (is there really any difference between the 2). i was thinking maybe a combo of the 990 plate with a front 990 brake in the rear should work. please tell me what i need before i buy this stuff.

Thanks in advance

anyone???

I'm not sure what a U-brake is. But don't give up just yet, it has only been an hour.

cycletourist, a u brake is a brake similar to the old mafac racer brakes of the 70s, only beefed up for BMX.

Not sre about mounting plates and whatnot though...

so a U-brake is like the center-pulls on my old Schwinn road bike?

yes

The principal difference between a centerpull caliper and a U-brake is that the arms of the latter are designed to be mounted directly onto braze-on frame or stay bosses, without the traditional slightly flexible mounting yoke. U-brake bosses are mounted above the rims, in contrast to below-the-rim cantilever or V-brake bosses, and the brake control arms cross each other between the cable connection points and the pivots. U-brakes were popular on late 1980s mountain bikes with under-the-chainstay brakes, and they are now seen primarily on BMX machines, many of which erroneously have only rear-wheel braking.

If you do not mind a bit of repainting and expense, one option is to ask a competent mechanic to braze on a set of U-brake bosses.

The mounting plate is the same for front and rear, but the brakes are different. I assume by 990 you mean Dia Compe AD990 brakes (Dia Tech 996 Hombres are very similar, threaded pads the only real difference). Basically the front ones have a pinch bolt in one arm and a barrel adjuster in the other (like a road bike caliper only the cable runs horizotally). Rear ones have a pinch bolt and a slot for a regular cable end, as they are generally used with stradle cables, similar to cantilevers. The best U brakes IMHO are Odyssey Evolvers. They use a clever system of interchangeable pinch bolts and adjusters so you can use the same arms front or rear. I would recommend you have some proper mounts brazed on if you want your brakes to actually work though. I've never heard anything good about brake plates. If you do use one though, make sure the bolt is long enough to fit two nuts on so you can lock them down real tight, or it will come off.

can you use the front u brake in the rear so that instead of using the stradle cable you can just have the brake cable going straight to the brake just like the front.

SO this is a u Brake?

http://images.google.ca/imgres?imgurl=www.yellowjersey.org/modolop.jpg&imgrefurl=http://www.yellowjersey.org/brax.html&h=480&w=640&prev=/images%3Fq%3DU%2BBrakes%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26sa%3DG

No, they're calipers. Pretty much the same as U brakes, just imagine the cable is running across the top rather than down the side.

ohhh alright, i got it, thnx =D