Brake Problem
 

Recently bought an inexpensive frame on Ebay in order to build a fixed gear bike for myself. I decided to mount a new set of linear pull brakes that I had. The back brake mounted perfectly although I had to drill out the mounting hole to receive the brake nut. The front brake was another story. i mounted the front brake into the mounting hole on the fork but the pads at their lowest adjustment contact the tire and not the machined surface of the rim. The pads are about a half inch short of the rim. It doesn't seem that these brakes are made for this application but I thought all these frames are standardized when it comes to mounting brakes. Obviously I'm wrong.

The brakes reach OK in the rear? Is the fork the same color as the frame? Perhaps you either got a fork designed for 27" wheels or an older 700C fork that needs a long reach brake.

How did you drill the brake bridge? did you get a right angle drill and short bit? or i think it is called a blind bit that goes in the hole before attaching to the drill?

If you just bored the hole through from the outside (now both holes are big) I would not use that frame. There is a good chance the brake will pivot in the large hole and not work correctly.

I did drill from the outside but made a short sleeve from another brake nut to keep the brake centered. Still don't understand why the brakes mount okay in the rear and not in the front.

Measure your axle to crown distance (the center between the forkrends to the brake hole) and you should get something like 370MM I believe or try an 27" wheel.

What brand bike anyway?

Brakes are made in different "reaches". There are "standard" reach brakes the worked well with most applications, but there are also "short" reach, generally for compact race bikes and long reach for other applications, such as mounting 700c wheels on a frame designed for 27" wheels. Further there is no standard for short or medium reach, so a medium brake for one brand may be a short on another; Campagnolo brakes run short. Some frames may be designed for medium reach brakes, but the medium brakes you are using are s shorter medium (again this is typical of Campy). As Bianchll said older cheaper frames and/or forks were made for a 27" standard that is larger than the 700c standard. If you have a frame made for a 700c wheel and a fork made for a 27" wheel, then the front brake would need a longer reach to work with a 700c wheel. Further just because a frame or fork was designed for medium brakes, does not mean the front and rear brakes reach will be identical. The front is usually on the short end of the pad adjustment and the rear on the long end. However, a 1/2 is a lot of difference, so it's likely your fork does not match your frame. Long reach brakes are still available however; http://www.rivbike.com/Sidepulls-Centerpulls-s/116.htm or http://sheldonbrown.com/harris/brake-calipers.html are some good choices.

The frame badge says Equipie LaZuatite. It's a steel frame advertised as a fixie and I'm trying to use a set of Oval R700 linear pull brakes that I had from a previous build. I wanted a single speed because there are no hills where I'm working and living at the moment. The brakes seem to be short reach and it could be that the fork was meant for a larger wheel. But then again a larger wheel wouldn't fit on the rear. It's possible that the fork and frame are mismatched. I guess I can either replace the fork, replace the brake or just use a rear brake.

Brake reach varies tremendously bike to bike to provide for different width tires and/or fender clearance. Brakes therefore are made in ranges like 39-49mm 47-59mm etc. Then the slots in the arms allow shoe height adjustment within that range.

Measure the needed reach from the center of the brake mounting hole vertically down to the center of the rim. If you have trouble doing this with the tire on, do it without, measuring to the edge of the rim, and adding half the brake surface width.

That's the reach you need, now you can shop for the correct brake.

BTW- for future reference never assume that any bike measurements are standard. The only standard there is, is that you can't rely on standards when it comes to bikes.

BTW, just a nitpick....

Linear-pull brakes do not mount in a single mounting hole, but on seatstays/fork legs, onto brazed studs. Linear-pulls are also known as "V-brakes".

You're mounting sidepulls.

Yeah he had me going at first, but as soon as he started in about holes instead of studs I knew he was talking about caliper brakes.

Well I'm looking at your brakes (assuming they are A700 not r700) and they are a whacky brake indeed. http://www.ovalconcepts.com/products...nere=4&idCat=1 Oval indicates that the front brake is designed to fit behind the fork and is not compatible with many bikes. However, the brake has a brake pad reach of 54.5 to 66.0mm !, so I'm wondering if #1 you are trying to mount it correctly (behind the fork) and/or #2 do you trying to mount the front brake with the drop down support?

http://bikeforums.net/attachment.php...hmentid=241854These do...

Oval A700 brakes are basic center-pull caliper brakes, regardless of what they're called. I sold these for a few years at the height of the Aero age. The only thing that makes them a bit unique is how the arms and cable route were tweaked so they could mound behind the fork, yet not restrict steering.

I take it one of these is your frame http://www.equipie.com/fixies.html; to bad you didn't get the normally included brakes :)

No, my brakes are the R700 model.

Sorry about that. I'm new at this.

That looks like my frame alright. Even the fork looks the same. I still don't understand why the back brake fits and the front doesn't. Shouldn't they have the same relationship to the rim? Shouldn't the distance from the mounting hole to the braking surface of the rim be the same? I can't imagine that a frame would use brakes with different reaches.

OK Is this a New? or used frame? Either way I think you need to check with the seller and see what they recomend or had on the frame.

When you started by saying you had to drill the brake bridge I assumed you bought a older used road frame that had been lightly refurbished.

A few pics may help too.

This may be a whacky idea but have you measured the two calipers you have to make sure that they have the same reach?

You mentioned in a post from higher up that you drilled the rear bridge to allow the brakes to mount. On a newer frame that suggests to me that you should have gotten the proper long bolt style so you didn't need to drill the frame. But it also suggests that since you drilled it from the back and right on through that the caliper on the rear may be angled down instead of sitting parallel to the seat stays. If so it would reach further. So it's possible that the rear isn't really long enough either but it worked out due to how you drilled the frame.

No, I drilled right through both existing holes in the bridge. The rear brake had the shorter stud therefore it didn't exit the rear of the bridge which is why I had to drill for the brake nut. The holes in the front fork were the same size but bigger so drilling wasn't necessary. The front brake had the longer stud having to pass through the fork. The frame was advertised as slightly used but may have been reconditioned. The seller had a number of them and may have bought them from the manufacturer as defects. Since I really would like to use these brakes, I think the best option for me is to purchase a steel fork from Nashbar. It's advertised as accepting short reach brakes.

Yes, the brakes have the same reach.

This suggests to me that the rear caliper is now cocked at an angle to the seat stays. The tube nut would act like a bushing on the front side of the hole but not at the back. So the caliper will assume an angle closer to vertical instead of mounting parallel to the seat stays. This angle is likely what is allowing the caliper to reach down a little more and work for you.

You could get a different fork or you could get some longer reach side pull dual pivot Tektro calipers. If you want to run with fenders the longer reach option would be the best.

No, that's not the case. The caliper is parallel to the seat stays and seams perfectly aligned with the brake surface of the rim. There is no issue with the rear brake. I don't intend to use fenders and am leaning to a different fork although fixing this problem is making a shambles of my budget. Oh well.