Bicycle Mechanics - Torque wrench for pedals? Confused.

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Mo-bile
04-22-06, 09:41 AM
I'm confused about how to use a torque wrench for tightening pedals since you have to use a regular wrench, not a hex wrench. How does that work since the torque wrenches seem to be designed to work with hex or sockets. Hope this isn't too stupid a question....


thomson
04-22-06, 10:31 AM
Most pedals have an allen (hex) bolt on the inside of the pedal (opposite side of the crankarm from the pedal)

However, I have not heard of anyone being so precise in tightening pedals. Lube the threads, finger tighten them, and then use a wrench to gently snug them.

Mo-bile
04-22-06, 10:34 AM
Thanks. I've just seen torque mentioned a lot and wanted to not screw anything up..too badly...


thomson
04-22-06, 10:42 AM
Thanks. I've just seen torque mentioned a lot and wanted to not screw anything up..too badly...

I understand the concern. I have seen a lot of pedals tightened too much. Just go easy. Think "snug" not "tight".

HillRider
04-22-06, 11:35 AM
For pedals without inside hexes, there is a tool called a "Crow's Foot Wrench" which is an off-set open end wrench with a square hole to take a ratchet or extension. These are used with torque wrenches on bolts thet aren't accessable to sockets or hex bits.

San Rensho
04-22-06, 11:55 AM
Snug is good, but heres another way of measuring the torque using a combination wrench and a fish scale.

Measure the distance from the center of the closed end to the center of the open end of the wrench in inches and fractions of. take the ft-lbs specification, multiply by 12 to get inch pounds, and divide by the inches you measured, that the number of pounds you will measure with the fish scale.

Put the open end on the pedal, hook the end of the fish scale into the closed end of the wrench and pull perpendicularly to the wrench until you reach the pounds you calculated above.

Mo-bile
04-22-06, 02:20 PM
Part of my confusion re how tight to tighten them was that when I took the existing pedals off, I could barely get them undone, they were on so tight.

operator
04-22-06, 04:21 PM
Maybe they weren't greased?

HillRider
04-22-06, 05:27 PM
Part of my confusion re how tight to tighten them was that when I took the existing pedals off, I could barely get them undone, they were on so tight.
I've come across that often. For some reason some owners and/or mechanics seem to think that they have to tighten pedals to fabulous torque settings. I have no idea why. You want them good and snug but there is no reason to tighten them super hard.

I tighten mine "snug" and never have to fight to remove them. Also, I have never had a pedal loosen by itself and have never had them damage the crank arm threads. If tight is good, tighter is not better.

robmcl
04-22-06, 07:53 PM
The spec on my Crank Brother Mallet C pedals was 25-30 foot-pounds, and I tighted them to 27.5 ft-lbs, which to me felt more than "gently snug".

HillRider
04-22-06, 08:31 PM
The spec on my Crank Brother Mallet C pedals was 25-30 foot-pounds, and I tighted them to 27.5 ft-lbs, which to me felt more than "gently snug".
Agree, that is way past snug. Again, I have no idea why the torque spec is that high as it seems totally unnecessary. It approaches the specs for bottom brackets and crank arms where the torque spec does make sense.

TSrider
04-24-06, 04:33 PM
Finger tight or just seated with a wrench is enough. They are tight to come off since they get tighter with normal pedalling motion. That is why the left pedal is reverse thread.

spunkyruss
04-24-06, 08:28 PM
Finger tight or just seated with a wrench is enough.....

I agree that you shoudn't go nuts when tightening pedals, but they need to be tighter than finger tight. This thread (http://www.bikeforums.net/showthread.php?t=177615&highlight=pedals+hand+tighten) was started by somebody that stripped three sets of cranks before learning that pedals need to be more than hand-tightened.

I think that it would help if Park Tool changed the name of the tool from "pedal wrench" to "pedal removal wrench." The large size of the tool only encourages people to tighten the hell out of them.

Park Tool would benefit, too. They could sell a smaller wrench and call it a "pedal installation wrench." They already sell some tools of questionable need. It would fit right in.

caotropheus
04-24-06, 08:39 PM
I agree that you shoudn't go nuts when tightening pedals, but they need to be tighter than finger tight. This thread (http://www.bikeforums.net/showthread.php?t=177615&highlight=pedals+hand+tighten) was started by somebody that stripped three sets of cranks before learning that pedals need to be more than hand-tightened.

I think that it would help if Park Tool changed the name of the tool from "pedal wrench" to "pedal removal wrench." The large size of the tool only encourages people to tighten the hell out of them.

Park Tool would benefit, too. They could sell a smaller wrench and call it a "pedal installation wrench." They already sell some tools of questionable need. It would fit right in.

SR, I just saw experienced mechanics of loud sounded bicycle brands, tightening pedals with that famous Park wrench "pedal removal" tool. I saw this here in Israel and the most serious part is that they were doing this in carbon cranks!

poopncow
04-24-06, 09:31 PM
clean and grease the threads, make sure that the "face" of the crank arm is clean and make sure the shoulder of the pedal axle is clean too.

Tighten only with as much force as you are willing to exert to remove the pedal :)
If your wrench is just under a foot, say 9 " , think 40#'s and you will be close enough :)

Good contact between the shoulder of the pedal and and the face of the crank with some elastic deformation from preload is the key.

miyata610
04-24-06, 09:42 PM
Finger tight or just seated with a wrench is enough. They are tight to come off since they get tighter with normal pedalling motion. That is why the left pedal is reverse thread.

Actually I think the opposite is true.

So why is the left pedal a left hand thread? Dunno.

Psimet2001
04-25-06, 12:22 AM
Actually I think the opposite is true.

So why is the left pedal a left hand thread? Dunno.

Nope...sorry. Has to do with the reversing of force directions that ball bearings exert in the presence of friction.

Check out this Thread (http://www.bikeforums.net/showthread.php?t=178939) about BB cup threading - I show a diagram for that scenario. Also there is a link from Sheldon Brown at the end.

ME.Alex
04-25-06, 12:51 AM
The purpose of torquing is to induce sufficient bolt stretch and, by association, thread tension.

Thing is, this is such a low-stress application that it doesn't matter. Just tighten them 'enough' + a quarter turn and don't worry. But absolutely do NOT overtighten.

buzzwire
04-25-06, 10:12 AM
I attempted to torque mine, but the torque wrench only works in one direction! Since one of the pedals is threaded backwards, I couldn't torque it. I just got a feel for how tight one was, and applied similar force to the other.

I try to torque fasteners whenever I can, especially when dealing with aluminum and composites. Learned this with auto repair long ago.