Bicycle Mechanics - Need help reinstalling crankset!

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Lenaxia
08-08-10, 06:45 PM
Hey guys, so I wanted to try to get to know my bike a bit better mechanically, and since the previous owner of my bike didn't take all that great care of it, there was a lot of build up. I decided to take it apart piece by piece and give it a good scrub down.
After putting my crankset back on, I can no longer shift onto my largest cog in the front. It is a triple, and the way it shifts now basically makes it feel like its one shift off (it shifts too far in on the smallest cog, not far enough to shift off, but cage rubs the chain).
The FD is a 6500 Ultegra braze on and the crankset is a triple 6500 ultegra octalink (the crank does not have to be pulled)
Any ideas? If needed I can provide pictures.
go1dens4
08-08-10, 06:47 PM
tighten the screw more, if you touched the front derailleur it is a problem with that if you are unable to tighten the crankset more
Lenaxia
08-08-10, 06:54 PM
tighten the screw more, if you touched the front derailleur it is a problem with that if you are unable to tighten the crankset more
The FD is a braze on, there isn't anything I could do to move it even if I wanted to. I did not remove the FD from the bike while cleaning it.
go1dens4
08-08-10, 07:02 PM
k then you did not put the crankset back on fully, by adjust the front derailleur you also did not touch anything with the cables right? Try to tighten the crankset more
Lenaxia
08-08-10, 07:08 PM
The crank arms are about as tight as they go. I may be able to get another half rotation out of it, but that wouldn't push the crank in by an entire index.
I also measured both side of the cranks. Both arms are exactly 3" from center of frame to center of crankarm. I am fairly certain that the crankarms are as far in as they go (220lbs on the wrench isnt going to go much further without shattering something.)
could I have messed something up in the BB? The bike specifically is a 2001 Trek 5200 with stock parts.
Lenaxia
08-08-10, 07:12 PM
I stand corrected. I went back and tried t obounce on it and got an extra full turn out of it and it sits correctly now. Thanks guys.
go1dens4
08-08-10, 07:13 PM
yes, If you did not tighten the (External) BB to the torque spec, make sure you are grease to the threads while doing this too. If the BB is not tight enough it would have the same problem if it is an external BB. If it is an internal BB then you would not have this problem and if you can get another 1/2 turn out of it then that would put it in a lot, you want to turn those old cranksets with internal BBs on pretty hard.
go1dens4
08-08-10, 07:17 PM
ha no problem, just do not go tightening anything else on your carbon that hard
davidad
08-09-10, 08:54 AM
Use a torque wrench. Solves many problems.
josephjhaney
08-09-10, 09:21 AM
Use a torque wrench. Solves many problems.
I second this sentiment! :) Just picked one up, and it makes a wold of difference when knowing how tight something should be. LOVE IT! :)
deinonychi
08-09-10, 12:06 PM
"If it is an internal BB then you would not have this problem and if you can get another 1/2 turn out of it then that would put it in a lot, you want to turn those old cranksets with internal BBs on pretty hard."
Just for anyone's information: Shimano 6500 is 9 speed Ultegra, which means that this is an Octalink crankset and BB. That means 36 to 51 foot pounds on the BB; and 25 to 36 foot pounds on the fixing bolt.
Using a torque wrench does indeed solve many problems, and it gives one a piece of mind too knowing that the bike is put together right! I have two: a Kobalt that goes from 10 to 100 foot pounds, which covers cranks, bottom brackets, and anything I want to attempt on my truck. I also have a Craftsman 0-250 inch pound (0-20 foot pound) torque wrench that works for stems, disc brakes calipers and rotors, Hollowtech 2 crank arms, and a bunch of other places.
I recommend using the torque specs in the appendix of one of Zinn's bicycle maintenance books, so far they've covered everything I've needed them to.
Lenaxia, keep working on your bikes! It's great fun and an important skill. Better to spend money on tools and books than to pay someone else to fix your bike.
HillRider
08-09-10, 06:01 PM
"Just for anyone's information: Shimano 6500 is 9 speed Ultegra, which means that this is an Octalink crankset and BB. That means 36 to 51 foot pounds on the BB; and 25 to 36 foot pounds on the fixing bolt.
It also means it's quite possible to not seat the matching splines on the crank and bb spindle properly. If they butt up against each other instead of mating properly, the crank arm will sit out too far and the first ride can damage the splines beyond repair.
I have two Ultegra 6500 cranks and I always remove the autoextractor collars before reinstalling the cranks so I can see inside the mounting area and be sure the splines mesh correctly.
badamsjr
08-09-10, 07:09 PM
+1 HillRider--I have one Octalink crank that acts like it is 'keyed'. If I don't put it on 'just so', it will not tighten properly.
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