Thursday, November 25, 2010

New Front Derailer & Brake






Ok, so I replaced the front derailleur with one that I modified with a larger cage. Well, it just didn't work out. The pantograph had too much free play, and the mount is too close to the chain rings to allow the springs to pull the chain onto the smallest chain ring, no matter how sturdy the cage was. Not exactly what I was hoping for. Maybe on another bike, that derailleur will work fine, but not on this one - not enough room to make up for the slop.

I found a Shimano Deore XT derailleur in my parts box, and decided to put it on. The clamp ring is quite a bit larger, so I had to make a pretty large shim, since it's aluminum and I don't have the equipment to weld on a smaller clamp. I think the reason I didn't use it a long time ago is because of the shimming, but I'm glad to go there now. This worked, and the front shifts beautifully.

On to the useless front brake. I measured the lever force at 8 pounds just to get the pads to move, not to mention apply braking force. It was just something about that particular brake (a very cheap one), and cable drag. I found that the cable housing was a smaller diameter (shifter cable housing), so that was part of the drag problem, but even with the correct cable/housing the brake was stiff and ineffective. So back to the parts box I went and viola! I pulled out a Dia-Compe road brake. I'm not sure of the model - something old and discontinued, I'm sure. It has a cam mechanism on the side to multiply the force applied by the cable.

I had to move the mount hole about 1/2" lower, as the Dia-Compe has a shallower throat. A steel 1/4" spacer welded onto the bottom of the fork stem placed a mount hole in the perfect spot. The brake looks good, the new lever pull is under 4 pounds, and I can't wait for the weather to break a little so I can test ride it.
Jack

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