Now for beam torque wrenches:

According to Gary Fitzhugh, Engineer at ôSDI Torque Productsö (makers of all sorts of torque wrenches and testing equipment), the adjustment formula for beam-type and dial-type wrench forward extensions is as follows:

TW = TA x L / L + A

TW = Wrench setting
TA = Desired torque at the fastener
L = Effective wrench length
A = Added length of the adapter extension

http://www.cditorque.com/main.html

So, for a beam wrench in the above calculations, the following is determined:

TW = TA x L / L + A
TW = 100 x 13 / 13 + 6
TW = 1300 / 19
TW = 68.42

ThatÆs the exact same number derived above using the other published formula. Notice the example given on their page for a dial-type wrench of 18.75ö with a 2ö extension and a desire to know the correct torque setting needed to achieve 250 ft/lbs at the fastener. The answer they show is 226 ft/lbs indicated. LetÆs try your formula which doesnÆt allow for handle length:

I = A / 1 + E

I = 250 / 1 + .1667
I = 250 / 1.1667
I = 214 ft/lbs.

Close, but not quite the same. Your formula appears adequate for some things, but not for others, and certainly not for ôclick-styleö torque wrenches which depend on a fulcrum and levers for operation and which must be allowed for in extension calculations. By the way, you can download a lot of good information from that site.

I was considering buying a 6ö extension and running the experiment by the various formulae and removing the adapter extension to check actual torque, but IÆll leave that exercise to anyone else who is interestedà. IÆve spent enough time on it.

One last thought û you might want to recheck the fasteners on your bicycle if theyÆre that critical. Wouldn't want you to hurt yourself. <img src="/forums/images/graemlins/wink.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />

Frank