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mechanical questions re new carbon fiber road bike

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mechanical questions re new carbon fiber road bike

Old 06-29-08, 02:02 PM
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cynergy
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mechanical questions re new carbon fiber road bike

Hi All - I just bought a new Carbon Fiber road bike (LeMond Versailles on closeout). It's the bees knees. I took it for a short ride home from the bike shop and it was really a joy to ride. Light, comfortable, quick.

During the ride I could hear that the front derailleur was rubbing on the big chainring. I used my Park Tools notes to adjust the front derailleur and it shifts really well now.

while I was adjusting the derailleurs, I noticed that the front derailleur was too low. It was practically rubbing against the large chainring, so I loosened the shift cable and the front derailleur clamp and raised it.

I would like to know how tight you are supposed to tighten the front derailleur clamp for a carbon fiber tube. I sort of finger tightened it, but didn't clamp down on it with the death grip like I do for my steel mountain bike. It doesn't seem to slide and the bolt is pretty snug, but I didn't have a torque wrench available, so I just kinda tightened it to what I thought was snug, but I think still on the light side.

How tight am I supposed to make the front derailleur clamp? should I be worried that I crushed/damaged the tube (it looks good to me)?

Also, the new bike is equipped with 105 brake lever/shifters. The bike was originally equipped with a Bontrager double chainring crankset (53/39) but I had my LBS replace it with a Shimano compact double (50/34). I believe that my brake lever/shifters will work with a double or triple chain ring set. When I shift from one gear to another, I have to push the brake shift/lever twice to go from one ring to the other.

Is there a way that I can adjust my Shimano 105 brake/shift lever so that it would operate in a double chainring mode (and not in a triple chainring mode)? It shifts well currently, but I do have to press the lever twice instead of once to go from one chainring to another.

Thanks in advance.
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Old 06-29-08, 02:13 PM
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the extra tick you hear when you shift is to trim the dérailleur so the chain doesn't rub on it in different combo.you need to tighten it to 40 inch's per pound.
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Old 06-29-08, 02:24 PM
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Thanks bikeman
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Old 06-29-08, 02:46 PM
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You should be able to shift from the inside ring to the big ring with one good shove of the brake lever.
When on the inside ring there should be no slack in the cable. You can try adding a little tension to the cable to see if that will get you on the big ring quicker, but it should not need much tension.
As for the click stops you can forget about them. When you shift go all the way with one throw of the lever. You can use the extra clickstops for trimming if needed, but you really shouldn't need them.
When riding on the 34 ring you may find that the chain rubs the side of the big ring when the chain is angled over to some of the smaller cogs.

Al

Last edited by Al1943; 06-29-08 at 02:50 PM.
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Old 06-29-08, 03:12 PM
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Thanks Al - i adjusted my derailleurs and they operate as you describe them. I do not use the 34 chain ring with the two smallest cogs since it seems to rub against the front chainring as you described.

I'm a little paranoid about the carbon fiber frame. Is it possible to crush the carbon fiber tube with the front derailleur clamp? I don't think I overtightened it, but I don't have a torque wrench, so I don't know how much torque I applied.

Thanks again.
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Old 06-29-08, 05:42 PM
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Originally Posted by cynergy View Post
Thanks Al - i adjusted my derailleurs and they operate as you describe them. I do not use the 34 chain ring with the two smallest cogs since it seems to rub against the front chainring as you described.

I'm a little paranoid about the carbon fiber frame. Is it possible to crush the carbon fiber tube with the front derailleur clamp? I don't think I overtightened it, but I don't have a torque wrench, so I don't know how much torque I applied.

Thanks again.
If you're going to do your own maintenance, then you need to stop and go buy a torque wrench. Guessing is a great way to damage your bike. You actually need two of them; one high-range and one low-range.
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Old 06-29-08, 06:32 PM
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What kind of torque wrench is good? I have a high range one that I use for the cars (120 in-lbs and up). Is the Park Tool torque wrench OK?

Thanks!
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Old 06-29-08, 07:11 PM
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the park tool torque wrench is ok .
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