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Old 09-06-08, 12:44 PM   #1
Flatballer
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Dura Ace BB Installation/Adjustment

Hi,

I've got quite a problem going on here. I bought a bike off eBay a couple weeks ago and have been fixing things with it ever since. The seller said he would no longer pay for any more work to be done. Initially I took it to two shops and they both said that the BB was installed incorrectly or not adjusted. One wanted about $80 to fix it, and one wanted $25. I took it to the one that wanted $25. The one that wanted $80 said you have to lever the drive side cup in when installing it. The other shop looked at me like I had 3 heads when I told them this. I can't find any evidence of it online.

Fast forward to yesterday, I get the bike back from the shop. I'm in the process of adjusting the FD and I notice that the chainring isn't parallel to the FD cage at all points. It moves in and out. This signifies either a badly installed BB, bent spider, or bent chainring. I took it back to the first shop on recommendation of a friend in the cycling club who used to be a mechanic there. The guy he recommended was the same one as before, and again said that there was play in the BB and it needed to be reinstalled and levered in. He again wanted $80 to do the work. He says he can feel play in the BB, but neither myself nor the guy at the second shop (who's been a mechanic for 14 years) can feel it.

The problem is that I've already had this work done once, and if something is wrong I should take it back to them. But if I take it back to them, they aren't going to believe me and are going to say that everything is just fine.

I still don't know what is bent, or how big of a deal it is. It looks to me like the outer chainring is bent, but the guy at the shop wouldn't even check because he's so convinced that there is a problem with the BB.

Please help, I have no idea what to do here...

Thanks,
Kai
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Old 09-06-08, 07:56 PM   #2
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Whatever you do, don't take it back to either shop... they sound like idiots.

Well, check for play in the BB yourself. Line up a crank parallel with a chainstay. Grab it at the pedal-end and push in and out. Do you see and feel play? Try the same for the other side. The play, if present, should be about the same. Use calipers to measure distance between crankarm and chainstay to find range of movement if you want.

I had a guy swear to me that his crankarm spider was bent because the chainring wobbled. He showed me that the left-crankarm had no lateral movement. But he didn't check the right crankarm! He hadn't tightened down the crankarm-bolt tight enough (really need at least 12" wrench for this). Unfortunately, he had ridden it with the crank wobbling for way too long and the taper was gouged out in the crankarm, so he needed a whole new crankarm.
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Old 09-06-08, 08:56 PM   #3
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I checked it out today, and had a friend I trust check it out. He said it was nothing to worry about, and I've got the FD set really well, so I'm not gonna worry about it. It's really a very small move at the end of the chainrings (each of them moves the same) but I can't feel ANY play in the crankarms. I'm thinking it might be the spider, but it's so minute (about 2-3 mm total deviation) that I don't think it matters.
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Old 09-06-08, 10:12 PM   #4
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If the BB bearings are tight with no slop, then you just need to true the chainrings. Slip an adjustable Crescent wrench over the chainring and using the FD as a guide, bend it in or outwards at the spots that deviate the most.
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