Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Bicycle Mechanics (https://www.bikeforums.net/bicycle-mechanics/)
-   -   Crank/Bottom bracket alignment/torque question. (https://www.bikeforums.net/bicycle-mechanics/901541-crank-bottom-bracket-alignment-torque-question.html)

gitarzan 07-15-13 07:06 AM

Crank/Bottom bracket alignment/torque question.
 
I know there is an optimal torque for bolting on the cranks to the bb.

I do have a torque wrench but do not own a set of Allen adapters.

Anyway, what I want to know... Is should the crank be tightened to the point where the the end of the square bottom bracket be flush with the bottom of the cranks hole?

Much like this?

https://www.google.com/search?safe=o...JOhr3wTzSpM%3A

I would assume that that be a matter of alignment of the chain line, BUT I have done things that made sense to be before and don't want to bugger it up.

The reason I ask is that while I lightly greased the BB end the wrenching is getting firm. Since I don't have the proper torquing setup, I want to be sure I do not bust bolt or crack my crank.

cny-bikeman 07-15-13 07:15 AM


Originally Posted by gitarzan (Post 15852165)
I know there is an optimal torque for bolting on the cranks to the bb.

I do have a torque wrench but do not own a set of Allen adapters.

Anyway, what I want to know... Is should the crank be tightened to the point where the the end of the square bottom bracket be flush with the bottom of the cranks hole?

Much like this?

https://www.google.com/search?safe=o...JOhr3wTzSpM%3A

I would assume that that be a matter of alignment of the chain line, BUT I have done things that made sense to be before and don't want to bugger it up.

The reason I ask is that while I lightly greased the BB end the wrenching is getting firm. Since I don't have the proper torquing setup, I want to be sure I do not bust bolt or crack my crank.

Absolutely NOT - the pic does not show that, but rather a spindle end that is slightly below the level of the surface of the crank. That pic shows the closest you generally should see the end to the arm surface. Also it's not great practice to grease the spindle flats, as it encourages overtightening. After making sure the flats on spindle and crank are clean of contamination (with steel wool, for example) the residual oil on your fingertips is actually enough in my opinion.

gitarzan 07-15-13 07:44 AM

Thanks. I'll go get a set of Allen's that will fit a socket tonight.

davidad 07-15-13 08:53 AM

Go buy the socket and torque the crank. Anything else is a gamble. It should be torqued to 25 pound feet.

Andrew R Stewart 07-15-13 03:58 PM

And next time don't gease the axle flats. This allows the arm to travel too easily up the taper. Andy.


All times are GMT -6. The time now is 03:31 AM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.