Bottom mounted V brakes?
 

I've been wanting to put a bike together for some time and today I got my starting point in the form of a Jamis Cross country, I don't know how old it is but I got a nice frame & headset for $15.

http://i37.tinypic.com/30vy7ah.jpg

Taking some bits apart I noticed the odd location of the rear brake mount(to the right of the bottom bracket), it looks like a pretty cool concept but I want to upgrade from the cantilever brakes to quick release v brakes and I want to make sure there'd be no problem with it before I get too excited.

http://i33.tinypic.com/2mmiqds.jpg

those are U brake mounts, you cant put a V brake on. U brakes can be found in the BMX section of most online parts sellers.

U-brake or roller cam brake only. Those are not canti posts. They're in the wrong place for cantis or linear pull brakes.

A campagnolo U-brake:

http://inlinethumb30.webshots.com/40...600x600Q85.jpg

The reason they won't work is because the posts for traditional cantilever and V-brakes are mounted below the contact point on the rim, while U/Roller-cam/Bolt on centre-pull brakes, the pivot posts are mounted above the contact points on the rim. You *could* mount V-brakes on it, and, iuhno, brake ON the tire. But that's such a bad idea.
Unless you're going for something like Paul Racers U-brakes are fairly cheap.
-Gene-

Is that depression in the chain stay manufactured, or a dent? If it's a dent it probably won't affect the strength of the frame at all, but it's worth checking the alignment of the frame to make sure the rear wheel tracks correctly. Run a piece of string from one rear drop out, round the head tube and back to the other drop-out, securing it there. Make sure it's level both sides then measure from the string to the seat tube. The measurements should be the same. also measure along the string from the drop out to the head tube on each side - again the measurements should be the same.

A great frame at that price, good find!

Thanks for clearing that up so fast, I've now read up on u-brakes and I assume that most bmx rear brakes will replace the old set (I've narrowed the age to 1986-88).

http://i36.tinypic.com/2nvav4k.jpg
http://i35.tinypic.com/llhkj.jpg

These are the front brakes and mounting points, these are cantilevers, no? The front brakes are the set that really need to be replaced as they fell apart when pulled off.

Great eye, I spent about an hour taking components off the frame and I hardly noticed the dent. Thanks for the advice too, I'll make sure to do that before I begin spending money on this bike

I do not think V-brakes will work under the chainstays for two reasons.

1). The cable line won;t work. U-brankles and roler cams had a centered cable alignment and a short pull right off the bottom bracket shell. There is not engough room for the cable to make a big left-hand swooping curve to hit the side of the V-Brake.

2). Even if you did manage that, the Noodle will likely get caught in the left crank arm as it goes around.

Find a U-brake or Roller cam.

None of that matters because U-brake mounts are in the wrong place. Take a look at the picture of my Peugeot. The mounts are on the wrong side of the tire. They're the wrong type of mount for cantis or V-brakes anyway.

There's a reason why you don't see brakes mounted there anymore...

V-brake and traditional cantilvers will NOT work.

Suntour Roller Cam or Shimano U-brake ONLY.

The dent is normal as its purpose is to clear the crankarm. U-brakes actualy served a usefull purpose. In the early days of mtb. design riders of smaller frames would hit their heels on conventionaly mounter cantilevers. The solution was a chainstay mounted U-brake. You'll notice that Miyata only spec'd U-brakes on smaller frames while bigger frames were spec'd with cantilevers. Linear pull 'V' brakes solved the heel hitting the brake issue.

Yep, standard issue mtb's around 1987 were canti's in front, U-brake in rear. Fortunately, they use the same levers which have a different amount of cable pull that V-brake. You want canti levers for both front and back on your bike. V-brake levers won't work well.

I wish that were so but I have a ~22" Yellow/Black (87?) Ridgerunner with U-brakes on the chain stays. I argued with the guys at the shop that I didn't want U-brakes but it was a warranty frame and that's what I got.