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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 12-10-06, 04:47 PM   #1
larrybhansen
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Need Bottom Bracket? advice

I need some advice with a problem my mountain bike (trek 8000 bought in 2003) is having. It makes an unfriendly noise when I pedal. It isnít a grinding sound and I can best describe it as a mechanical groan. At first, I only heard it after I had been riding a while, like 20 or 30 minutes, as if it was after things warmed up. Now it starts right away. It groans only when I am climbing and only when I am pushing the right crank.

I have changed pedals, made sure my front derailer wasnít dragging, and put on a new chain. Once on a different bike I had a weird noise and it turned out to be the seat post but that doesnít seem to be the case now; I removed the seat post, rode it up a hill and still heard the agonizing groan. It sounds like it comes from the crank or bottom bracket. I removed the bottom bracket and it turned freely, although there was a hint of powdered metal on it. Also, I couldnít get the left bottom bracket adapter off but was able to remove it from the right side. I am wondering if this will be a problem if I put a new one on.

I am most suspicious of the bottom bracket mainly because the groan seems to come from there. The BB was marked TRUVATIV Model # BB-03-SPL-SL-113-68(E)/73. I checked the TRUVATIV web site and it appears this model is not available. The best I could tell was a newer model GigaPipe Team SL BB, ISIS-68+E/73x113mm would work.

I would appreciate comments telling if this sounds like a bottom bracket problem or what it might be. And if I get a new BB
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Old 12-10-06, 05:25 PM   #2
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It could be other things, but it sure sounds like a BB to me--especially if you're seeing metal shavings. I'd just let my LBS repair it if you don't have the tools. The guys there should be able to do it fast and relatively cheap. It's a standard size, and a new one should last many, many miles. You can get a good one for about $30-40 + labor. It should cost about $10-20 in labor. If you want to do it yourself, it's not rocket science, except they can be a bit difficult if it's corroded, etc. Modern BBs are pretty durable, but on a Mtn bike, things can get pretty grungy and if it got submerged, that doesn't help. Perhaps other posters can recommend a good replacement. I like Shimano for my road bikes, but don't ride a mtn bike. Good luck.
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Old 12-10-06, 06:34 PM   #3
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Quite likely you can pull the old bottom bracket out, clean off any grunge, and reinstall after greasing up the threads. The noise comes from the cartridge walking around inside the frame slightly and cleaning/geasing often solves the problem...for a while.
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