Bicycle Mechanics - centaur bottom bracket spindle length

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jks84
03-31-09, 06:28 PM
I just finished up a build of an '04 trek 1500. I am using a campy centaur crank/bottom bracket. I read somewhere that since the seat tube was 35.0 mm I needed a 115.5 mm spindle length for my double crankset as opposed to 111. Is this true? I have a 115.5 on there now and it seems okay. How much clearance between the cranks and bb should there be?

LarDasse74
03-31-09, 07:16 PM
AFAIK, spindle length should not vary with seat tube diameter.
Ex Pres
03-31-09, 07:47 PM
You need to measure your chainline. Should be around 43.5mm to the center of your two rings. But the real issue is does your front deraiileur swing cover the entire range it needs to to shift onto both rings?

jks84
03-31-09, 08:16 PM
The fd covers the full range to shift from low to high. I measured the chainline the best I could and it looks like it is a bit more than 43.5. Here is a pic of the spindle:

http://img27.imageshack.us/img27/830/1000272.jpg
shelbyfv
03-31-09, 09:42 PM
With a large diameter seat tube, the FD may bottom out and not retract far enough to access the small ring. That is why the BB spindle needs to be longer, moving the small ring away from the seat tube.
DaveSSS
04-01-09, 08:41 AM
The 115.5mm length is only needed for a triple crank and 32-35 seat tube diameters.

The easier way to measure the chainline is from the side of the ST to the tip of a tooth on the little ring (about 23mm) or to the tip of a tooth on the big ring (about 30mm).
jks84
04-01-09, 09:48 AM
Do you mean a triple crank with a 35 seat tube diameter or any crank with 35 diameter? Sorry for all the questions!
DaveSSS
04-01-09, 10:17 AM
Do you mean a triple crank with a 35 seat tube diameter or any crank with 35 diameter? Sorry for all the questions!

Triple only. www.campagnolo.com has all the answers.

See page 11 of the PDF.



http://www.campagnolo.com/repository/documenti/en/7225218-Bottom_bracket-06-06.pdf
offtheback
04-01-09, 10:41 AM
It ALL depends on the seat tube diameter. You do not need a 115.5 to run a triple. I run one with a 111. From Campy: 111mm is for use with double and triple cranks with seat tubes smaller than 34.9mm. For 34.9/35.0mm seat tubes, use the 115.5 Centaur, #0207

Plus with the 111, you get a slighty better chain line from the small or middle chain ring to the lowest gear in back.
jks84
04-01-09, 11:00 AM
Excellent, that is what I needed to know. Thanks!
DaveSSS
04-01-09, 03:21 PM
It ALL depends on the seat tube diameter. You do not need a 115.5 to run a triple. I run one with a 111. From Campy: 111mm is for use with double and triple cranks with seat tubes smaller than 34.9mm. For 34.9/35.0mm seat tubes, use the 115.5 Centaur, #0207

Plus with the 111, you get a slighty better chain line from the small or middle chain ring to the lowest gear in back.

Campy says to use the 115.5mm spindle with both 32 and 35mm STs. Of course if you can get the FD to shift into the little ring with the 111mm, that's all that you need.

http://www.campagnolo.com/repository/documenti/en/7225218-Bottom_bracket-06-06.pdf