Bicycle Mechanics - Torque wrenches
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
07-19-02, 07:37 AM
Here's a question for all of you shop guys: do you use torque wrenches?
The reason I ask is that I'm doing a build project that involves the installation of a Campagnolo Veloce BB. The problem is that the Park tool for this procedure is a long-handled wrench and not something that I can snap on a torque wrench [like the tool I have for Shimano BBs]. So the real question is whether I really need the torque wrench for this [Campy provides the troque info in the installation instructions], and whether I can just do it by torquing down by hand... blindly. It's an aluminum frame, though I doubt I have the strength to crack it in this procedure.
Many,many,many BBs get installed without torque wrenches.The Italian threaded ones need to be EXTRA tight.
I'm getting ready to build up frame and I've wondered
the same thing. Do I really need a Torque wrench?
I've checked the Park ones and they are way expensive,
went to LHS (local h.ware store!) and saw even more
expensive ones. Sears looks like best bet, but again,
do I REALLY need it?
07-19-02, 11:44 AM
I don't think torque wrenches are truly necessary if you've worked with bicycle components for a while, and know how tight is too tight and risks stripping threads or fittings. Bicycle mechanics might use them to satisfy the concerns of very picky/paranoid customers, or if their shop has such a policy for liability reasons. Personally, I have a nice Snap-On 100-600 in-lb for quill stems, cranks and bottom brackets, and a Craftsman 25-250 in-lb. for the smaller stuff. I used the smaller one on suspension fork crowns a lot, since that did seem to be an area of liability concerns. But on mundane stuff like installing a derailleur, I just went by feel.
velocepedio, you should be fine, just grease up the threads well and stop if the unit doesn't seem to be going in properly. I don't think it would be humanly possible to strip the threads with the tool that Park Tool makes for that BB, unless you added a pipe for leverage. Even then it would take a big lack of common sense. ;) And it will need to be quite tight, especially if it's Italian-thread as pokey said.
Look at the torque specs. Let's say they call for 45 ft.-lbs. This is 45 pounds of force on the end of a 1-foot-long wrench. If the wrench is 2 feet, you'd use 22.5 pounds of force on the end of it. So if you want, you can estimate the torque you're applying in this fashion.
07-19-02, 11:53 AM
We use torque wrenches for specific parts. Bottom brackett installation and crank installs are two that I recommend using a torque wrench for. Most of the others components you could tighten by hand. Remember, when it comes to bike repairs, you do NOT need to be ham fisted! You're usually tightening a Hardened bolt or nut into aluminum. You can EASILY strip most everything out. We use to torque wrench not to make sure it's tight enough, but to make sure it's not TOO tight!
For bb installs I sugest greasing the threads. For our more expensive bikes (including aluminum frames) we use Anti-Sieze compond required for use on titanium products.
For crank arm installs, if it's square taper we do NOT grease the flats, yes for the bolts. For splined, we DO grease the flutes and the bolts!
There are two categories for torque wrenchs, the adjustable (more expensive) type and the scale type. You can buy the scale type (has a needle and a gauge) for only about $15-20 USD at almost any hardware store and of course Sears and Home Depot. They're easy to use and will work for most of your applications.
I own two of the adjustable kind. One in In-lbs and the other in Ft-lbs. The first is a Husky (Home Depot) and cost just under $50. The other is a Craftsmen (Sears) and cost about $120. For bike repairs, you can get by 99% of the time in just needing the cheaper in-lbs one. Sure it seems like a lot, but the next time you overtighten a $35 bottom bracket in a $1400 frame, you can easily justify the need for a $50 tool!
07-19-02, 12:01 PM
a2psyklnut, I think I remember Campy making a tool that would allow using a torque wrench on the older BB design where there are semi-circular notches around the edge of the flange... but I don't work in a shop anymore. Could you peek into the United Bicycle Tool catalog and tell me if they list such a creature? I think part of velocipedio's issue is that there's no way to use a torque wrench on Park Tool's tool for this type of BB, which is like so:
07-19-02, 12:14 PM
Thanks for the replies.
My problem is not in using the torque wrench -- I've used one and will use one in a related project involving a Shimano BB install -- but that Park tool, as mechBgon observed, dosn't let me use a torque wrench. I know there's a Campy tool and a TacX tool for use with a torque wrench, but while the Park tool sells for $12.00 Cdn and is easily had, the Campy and TacX tools sell for $50-$60 Cdn, and are hard to find [can't get them in online shops, I'd have to special-order them through the LBS and they have to be imported because the distributor has none in stock!]. My preference would be to not spend $50-$60 on a tool that I will use once a year at the most [we're talking catridge BBs here, not a lot of maintenance to be done] when I can get by with $12.
So... If I can torque it down myself without the expensive tools, I surely will.
Another thing... I've always used grease on BB threads... any reason why I should go with anti-seize compound?
07-19-02, 12:18 PM
I'm curious what the recommended torque is for that BB unit, and whether it's Italian- or English-thread?
07-19-02, 12:21 PM
Also, velocipedio, I did think of a way to use a torque wrench on that tool, and that is to get a large, cheap socket which fits the rim of it, and have someone spot-weld the socket to the rim of the BBT-4 tool. Then you could use a torque wrench, although you might also need to pick up a 3/8"-to-1/2"-drive converter if your torque wrench had a 3/8" drive square.
07-19-02, 12:21 PM
Sorry MechBgon, nowhere near our catalogues today! So I can't find a pic.
and Yes, you can tighten by hand, just don't overdo it!
We use anti-sieze only because we are in a hostile climate. I'm down in the West coast of Florida and there is ALWAYS salt in the air. We do this to keep from the bb's becoming a permanent part of the frame!
We had a guy come in that was a Tri-athlete and would never rinse his bike off after coming out of the water and then sweating all over his bike. The headset was shot, both hubs, and his bb too! We could take apart everything but the bb. It took two guys holding the frame in a repair rack and another guy with the bb tool and a LLLLLOOOOOONNNNNNGGGGGG piece of pipe to finally break that bb loose!
07-19-02, 12:34 PM
70 N.m, English thread. That's tight, if I remember correctly, but not impossibly tight.
07-19-02, 12:46 PM
If you are applying force with a lever about 20cm long, which is my estimate with that BBT-4 tool, I'm calculating you'd need to apply the force required to lift 35kg. 35kg x 9.8m/s.s x 0.2m = 69 N-m. Hope that's some help :)
kragens have cheap $10 basic ones. kinda long and awkward to work on bikes maybe but they work fine on my car
07-20-02, 07:56 AM
I note that Shimano give a range of 50-70 n.M for their BBs. I'm thinking that Campy's 70 n.M is a range more than a specific torque. I think I can estimate torque within 30% by hand...
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.