So I am putting new calipers on my bike, and I notice that several of the “installation steps” call for torquing. I have never torqued anything–just put it on and cranked until it felt “right”. Now I suppose there are some things on a bike that, done properly, are to be torqued, and I guess if Shimano didn’t have torque specs, some one would complain “Hey, how come no torque specs–how unprofessional”, but do you guys actually bother with torquing specs on brakes–I will not believe you if you say yes, but let’s hear it-----
FYI, I don’t even know how to tourque anything. But I think brakes are pretty important.
Sufficient torque is two grunts and a groan.
Seriously, when I raced cars and go carts this was very important. I’m amazed at how difficult it is to get bike torque specs. The only advice to give is don’t over torque under these circumstances.
No, but mechanics are always saying how a lot of bolts are over torqued and on the verge of stripping. Anything threaded into aluminum should be treated with care as aluminum is easy to strip. I know of one case of a lack of a torque spec in assembly costing a company over a million dollars when the had to replace broken equipment.
most the time if your tightening up a bolt on a bike you can go at it till it feels tight, what you are trying to do is basically tighen the bolt enough to stretch the bolt to about 35% preload. most of the bolts we use nowadays should be at least grade 5 which has a high strength and very adequate, but some people use stainless bolts which are weaker, best choice between strength and weight would be titanium bolts, not that expensive either. so an easy answer is this.
if your clamping metal to metal such as a stem or a aluminum seat post, torquing till its tight is good.
Now if you are doing a comonent like carbon fibre like a seat post then be carefull . what you could end up doing is squashing the post too much and putting too much stress into the post so that it fails because you crush the tube thats why most aero bars and such have torque specs on them . Also bottom brackets, not so bad but you could in theory crush the bottom bracket and reduce clearence and thus efficiency of pedaling if too tight. mind you nowadays you would have to use a big cheater bar to overtorque most things, but carbon is the exception. I have never used a torque wrench as yet apart from my last bottom bracket as it was troubling me but then again I work in the field as an engineer torquing things all day so with my weight and the length of tool I am using you can quickly guess pretty close how tight you are torquing something.
if you want torque specs for anything on a bike go to park tools website
Monk,
If you are checking your bike alot, like I do, there is no need to over tighten anything. I’m a bike mechanic and do all my own work. I work on my bikes a number of days per week. I HATE things that are stuck, way over tightened, this is not neccessary. Just don’t break it…check it often and you’ll be fine. I’ve never used a torque wrench on a bike.
I dunno Paul. As former professional bike wrencher, assembling a bike using a checklist and a high quality torque wrench was about the only thing that kept me from losing sleep every time we sold a bike.
Here’s some lessons I learned the hard way.
-
If you ever work on someone else’s ride, use a torque wrench (and of course the mfg’s specs or Barnett’s or Zinn’s or Sutherland’s or Park’s charts)
-
Never work on a bike when you are tired; like the night before a race at 11 p.m. in dim light with a messy bench. (Ask me about that one some time.)
-
Get a good torque wrench, preferably one with a dial guage, and baby it like the precision tool it is. READ THE INSTRUCTIONS THAT CAME WITH THE WRENCH BEFORE YOU USE IT AND PRACTICE ON A JUNKER BIKE TO GET A FEEL FOR THE TOOL.
-
Check your bike bolts at least once a month and lube all bolts unless the mfg. says not to.
-
You’ll be surprised what at what 350 inch pounds really feels like and wonder how the hell your cranks ever stayed on the way you used to tighten 'em.
Or don’t. Using a torque wrench takes a lot of the edge and excitement out of bike maintenance. It’s not for everyone; just those of us that take a lot of pride in the hidden stuff in the world that works. Like copper water pipes for instance.
http://www.parktool.com/repair_help/torque.shtml
Make sure to not use one of the rotary click torque wrenches as they have to be regularly calibrated - the lever arm ones don’t go out of calibration unless you bend them too much.
Does no risk of overtorquing apply to the BB as well. Ultegra BB (bb=5500?) installation guidelines have no torque specifications, but DA does.
Is it possible to overtighted the DA BB (like it is when you repack bearings in a hub)?
Thanks
Jude
You have to be careful when tightening things into a frame if the frame is made of aluminum or has a threaded aluminum insert as these can be stripped -mostly on the initial insertion, but under and overtightening are not good.
It still amazes me that bike mechanics don’t use torque wrenches. YES, you need to use them and at least on your first build, check each nut and bolt.
You can pick up a wrench from Park Tools or any good hardware store. Most bolts break because they were over tightened. You do develop a feel for this but you always want to check the bike when you are done.
It’d be great if everyone had the discipline to use a torque wrench all the time, but here’s where it is important:
Expensive stem steerer tube and h-bar clamp bolts
STI lever/brake lever/shifter clamp bolts
BB shell - the crank bolt too, but most people know to crank that mo fo down
waterbottle cage mounts
seatpost clamps
Anything outrageously expensive or unique to the design of that particular component (a good example would be thomson’s unique steerer tube clamp)
.