veganaise

So, this is the 3rd time since the beginning of the year that I've stripped threading or destroyed something through over tightening.

The first was tightening the clamp on a cheap, no-name stem. Both the stem and the bars were 26.0 clamp diameter, according to the shop that sold them to me. I could never get the clamp tight enough to keep the bars from eventually rotating. It eventually gave. Looked like it was forged aluminum.

The second was tightening the cable clamp on some old (old!) Weinmann brakes, shearing the bolt in two.

The third was last night while I was tightening a no name seat post collar, trying to eliminate creaking from the area (removed post, cleaned up as much dirt as I could from tube and post, light grease before reinserting). The pivot on the collar looks to be brass. It's been loosened and tightened a number of times and I've had a lot of trouble keeping it tight enough to keep my seat post from migrating down the tube. Started tightening and felt the tell-tale give.

Anyone else go through this problem? Is it time I buy a torque wrench? I don't want to keep destroying parts as I slowly upgrade.

gmason

Apparently past time.

GV27

Indubitably!

https://www.worldcycling.com/merchant...ct_Code=PTLTW2

veganaise

Okay. 2nd question: If I've already stressed some threading by over tightening, is it permanently damaged even if it hasn't stripped? Would the torque specifications be the same in this case?

GV27

If you've already stretched the threads it's anybody's guess. The torque specs are a torque that is "tight enough" but not damaging.

I'd go for the original torque spec and cross your fingers.....

cny-bikeman

One thing you need to do is to modify your "troubleshooting" technique. Make it tighter is not always the best solution or sometimes as you have discovered any solution. If one works at a problem and is not able to solve it after a reasonable amount of time and effort then the first course of action is to throw out your previous assumptions and start over, thinking as logically as possible about possible causes and cures.

If that still fails then consult expert opinions or give it to someone else who is skilled at the task.

veganaise

I'll admit I have a lot of room for improvement. But I'm at least better than I was last year, or the year before. I should be making more use of the Mechanic's forum, though.

mike

You don't need a torque wrench. You just need more common sense. Try shimming to see if that helps.

Sometimes, if you overtighten some parts - especially aluminum parts, you can crush them and they won't fit. I have seen people do this with seat posts. Then, they end up with parts of the post that are tight and some that are loose and they can't figure out why.

tellyho

From your description, I can't say I'd do anything differently. I think a torque wrench is overkill on a bike. I'd lean in the direction of cheap parts.

gmason

Now look, every time someone asks about a torque wrench, some respond that they are unnecessary. For some, with enough experience, that may be true. But this person came here having destroyed more in parts than it would probably cost to buy the tool.

Why not respond that not everyone is mechanically gifted or experienced, and that for their own sake, they should get a torque wrench. It can't hurt, and may save a ton in LBS costs or additional ruined parts.

GV27

^^^^ What he said.

I only use my torque wrench on stuff that I know is delicate or that I want to get just-so. That list as as follows: anything on carbon bars, steer tubes, etc., the pinch bolts on integrated-bb cranks (I pulled the threads out of an XT one WITH a torque wrench once - Shimano subsequently went from 15mm bolts to 19mm), crank bolts on square-taper BBs and the cassette lock-ring.

Everything else I just do by feel and don't have a problem. But I'm very experienced and for whatever reason seem to possess a naturally-high mechanical sensitivity. He's damaging multiple parts. He needs a torque wrench.

Where can he buy that? A torque wrench can teach him how tight is tight-enough. Same goes with troubleshooting. Does it need to be tighter? Well, I'm up to the correct torque, so let's look elsewhere.

mike

Even the professionals goof up sometimes. I am working on a USA made TREK mountain bike. Whoever put on the shifters screwed them in so tight that the bolts went right into the aluminum bars.

It was impossible to unscrew the tiny bolts with their frail allen key heads, so I had to cut the shifters off of the handlebars with a disc cutter. It was a real mess and I curse the droopy eye mechanic who did it.

Anyway, you are not alone in your dilemma.

gmason

In the very late 1950s and early 1960s I was very much into sportscar racing. As a pit crew and mechanic, not a driver (which I still lament). I worked on a lot of cars - mine and other people's. Theirs were always much more expensive than mine.

These torque wrench discussions always make me wonder what the owner of the 250TR Ferrari, SWB Berlinetta, or Lotus 18 I was working on would have said when I told him that I was using common sense when I stripped out the threads in one of those beautiful cylinder heads, or the body of a 40DCOE Weber carb while I was reassembling it.

neil0502

gmason: I happen to agree with you 100% ... with one caveat: a torque wrench STILL requires a bit of understanding about threads and lubricants, AND an understanding of its proper use.

I hate to ever go with "... that goes without saying ...."

Park Tools' website, incidentally, has a good page or two about fasteners, generally, and torque, torque values, and application OF torque.

gmason

Very true.

veganaise

Thank you for pointing this out. Looks like I have some reading to do tonight.

gmason

And FWIW, I believe the 1958 Scaglietti bodied (pontoon) 250TR to be one of the most beautiful sporting cars ever built. Others being the Maserati 300S, Scarab, Lotus 11, Jaguar D-Type, and Aston-Martin DBR1. Well, OK, and the Mercedes 300SLR. Oh, and ...

El Julioso

I used to do a lot of mechanical work on cars as well (before I started disliking them for environmental and social reasons). I used a torque wrench for practically everything I did with cars.

Now that I'm a bike mechanic, I only use torque wrenches when there is a danger of crushing something; most notably, carbon fibre. I know when something is tight enough not to come loose from experience, and I can feel when a bolt is about to strip (either the threads or the head itself). The feeling in the bolt dramatically changes at that point, from one of solid resistance to gentle acquiescence. A bolt will always increase in resistance as tension increases, due to increased friction, unless either the head or threads are stripping. So if you're tightening something and it suddenly becomes easier to tighten, back off

Carbon fibre, on the other hand, gives no warning when it is about to crack. I haven't cracked any carbon fibre parts yet, but I don't intend to either. So a torque wrench has obvious application there.

cny-bikeman

"So if you're tightening something and it suddenly becomes easier to tighten, back off" I would consider it too late by then. What I have said when training mechanics is that the resistance will increase markedly when it is "tight enough." A lot of it is still experience (ALL of us have stripped a bolt at one time or another) but that guideline seems to help.

mike

Well, everything is relative. Tightening a bolt on a bicycle handlebar is considerably different from working on a 250T Ferrari cylinder head.

When I said "you don't need a torque wrench, you need more common sense", I did not mean it in a demeaning way. Maybe I should have said, "you need more experience", or you need more, "hand finesse".

You can't be much of a mechanic if you have to rely on a torque wrench for every bolt you tighten on a bicycle - where does it end? How do you tighten spokes without a special tool or know if you have the rear carrier nut on tight enough? It is something like a chef who has to rely on the recipe and a measuring spoon to add seasoning. You simply need to be able to go by feel at some point.

gmason

And I agree with all of that. But if you look back at the myriad threads about the need for torque wrenches, I think you will find that most say, in essence, "don't bother, you don't need one." In fact, some people do, and I suspect that many give up because they break too much or spend a lot they don't need to.

Teach a man to fish. It is the best function of this particular Forum.

neil0502

I agree with all of that, too.

I also think (and I say this with something between respect, admiration, and awe ) that there are more than a few folks on this forum who have been wrenching so long that they can do it in their sleep.

That's not me.

It reminds me of the baseball legend, Willie Mays, who--when asked the secret of his greatness--replied:

Thanks, Willie. I'll just run right out there and do that ....

El Julioso

I myself very rarely get to the point that a bolt becomes easier to tighten anymore (generally only with Phillips heads, which are crap anyway), and that is because I rounded a few bolts a little bit years back to learn where that point was. The resistance of some bolts, such as crank bolts, will increase markedly before they are "tight enough", so it just takes experience to know when bolts like that are tight enough not to come loose while riding.

The only bolts I've ever stripped badly are those with Phillips heads that are seized tightly. I curse Ford all the time for causing the Robertson head bolt (which is FAR superior to Phillips) to become relatively rare.

veganaise

Good freaking crap. I bought some Tektro road levers to replace some ratty used Exage levers I've been using for the last 3 years, most recently mounted on a set of moustache bars. When installing the Tektros, I tightened until they were solidly in place, then I'd do a quarter turn then check to see if they move under pressure. They kept moving and I kept tightening. I'm sure by now you can guess where this is going. POP! After a bit of searching I found that the top part of the plastic body (closest to the stem) under the rubber hood snapped due to too much pressure being put on it. It didn't come completely off. I guess these things were designed to be mounted on the bends of regular road drop bars and not on the relatively flat section of a moustache bar. Anyway, I tightened it up until it was safe to ride on, wrapped the bars, then promised myself to stop ****ing with my bikes before I do something stupid enough to get myself killed. Hooray for wasting $30. That is all.

mike

Ya, OK. You have a good point. Torque wrenches for the folks who don't quite have the touch yet.

I wonder, though... How do you know how much to torque each of the almost infinite number of parts on a bike and all the variations thereof? Seriously? Is there a general rule as to how much to tighten? Hubs, pedals, stems, holy smokes!

I am willing to bet that I could do right it by feel, but would get it totally wrong with a torque wrench.