Bicycle Mechanics - Rear Derailleur Tension Estimates

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mooklekloon
03-27-07, 07:54 AM
Hi,

I was hoping someone could help me out. I need a quantitative estimate of the maximum tension that the rear derailleur cable on a typical bike would be under. If anyone has ever measured this, or knows where I could find this number, I would be very appreciative. I used the word "typical" on purpose. I need only a very rough estimate, so for example, this could be for a recent ShimanioTiagra 8spd. Any numbers would be very helpful.

I am also interested in the total cable travel. i.e. Between shifting from gears 1-8 (or 9 or 10) how much cable is wound up in the shifter? 5 inches? 10 inches?

Your help is very much appreciated

Al1943
03-27-07, 08:04 AM
The tension changes some as the derailleur is shifted to different cogs. In the smallest cog position there is not a lot of tension on the cable. As the derailleur is shifted to larger cogs the derailleur spring is being compressed.

Al
AndrewP
03-27-07, 08:09 AM
The travel is in the order of 1/2 in and the tension about 3 lb.

mooklekloon
03-27-07, 08:26 AM
The travel is in the order of 1/2 in and the tension about 3 lb.

Thanks!

1/2 inch per gear? Or over the whole set of 8 or so?
mooklekloon
03-28-07, 02:04 AM
Anyone other estimates?