 |  | | | |  | |  |  | Just real tight or Torque? |  | |  |  | |
 Posted: Sat Mar 27, 2010 3:56 pm |
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| Frenchbuilt |
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| Joined: 18 Apr 2007 |
| Posts: 443 |
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Hi late night question? In the past I never really cared but is there a torque
figure for bolts holding the arms to the axle on Stronglight (93) cranks.
Real tight is what I use to do but now I am more refined and worried.
Thanks, Dan |
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| | | | | | | | | Bolt Torque Specs | | | | | |
| Posted: Sat Mar 27, 2010 5:33 pm |
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| verktyg |
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| Joined: 14 Jan 2007 |
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| Location: SF Bay Area |
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The numbers I've seen bandied about over the years were 20 foot-pounds and 30 foot-pounds of torque.
The reason torque wrenches are used is to not only insure that nuts or bolts are tightened sufficiently so that they don't come loose but also to avoid overtightening them.
Torque ratings are based on the strength of the bolt. For a cheap M8x1.0 bolt the spec can be as low as 10 foot-pounds. The strongest M8 bolts are rated at 27 foot-pounds.
http://www.engineershandbook.com/Tables/torque1.htm
There's also an ongoing controversy in the bike community about lubricating the crank arm bolts before installing them.
Don't lubricate the spindle taper or crank arm taper.
The only crank bolts I've seen break were during the installation of titanium or aluminum bolts. They shouldn't have been used to tighten down the cranks in the first place. Steel bolts should have been used first then removed and the weight weenie bolts installed afterward.
I lubricate crank arm bolts with a little grease and tighten them to about 20-25 foot-pounds especially when reinstalling old cranks as they may have been run loose at some time.
I also inspect the crank arm bolts and look for signs of damage. I replace any bolts that have rounded off corners from sockets or wrenches slipping. They may give you problems getting them out the next time.
It's important to retighten the bolts after 50-100 miles of riding, sooner if you're hammering hills or sprints. I've had crank arms loosen up on a long ride before.  |
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Chas.
SF Bay Area, CA USA
==============
1984 Criterium
1969 TdF
1971 TdF
1974 TdF
1984 TdF x 2 Bikes
1970 SC
1971 SC
1972 SC
1984 SC
1984 Team Pro
1985 Professional
1990s Team Replica |
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| Posted: Sun Mar 28, 2010 3:25 am |
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| sandranian |
| Site Admin |
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| Joined: 27 Feb 2006 |
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| Location: Southern California |
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| Stupid C-Record "Self Removing Bolts" loosen up all the time. I have to carry a 7mm Allen wrench on rides because of it. |
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| Posted: Sun Mar 28, 2010 6:23 am |
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| Frenchbuilt |
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| Joined: 18 Apr 2007 |
| Posts: 443 |
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Thanks, I was actually worried about over tightening.
These numbers seem right for this set up.
Photos of cleaned up bike coming soon.
Dan |
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| Posted: Thu Apr 01, 2010 1:28 pm |
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| Wisey |
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| Location: Brisbane, Australia |
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| sandranian wrote: |
| Stupid C-Record "Self Removing Bolts" loosen up all the time. I have to carry a 7mm Allen wrench on rides because of it. |
Another of the wonderful 'improvements'  brought to us by the masters at Campagnolo.......... like the Delta brake, and their marvelous clipless pedal, and.............................  |
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Kind Regards,
Wisey
Delta Dreamin' |
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