installing bb/crank without torque wrench
 

so just wondering what the general consensus is on this, is it absolutely necessary to have a torque wrench for installing an external bb and crankset? or will i be okay just... 'winging' it?

The best answer is "always follow correct torque specs."

That said...

There are plenty of folks out there wrenching on their own bikes who have probably never even seen a torque wrench in real life before though so it can be done without.

You can get away with it if...

..you are very experienced with a wrench and know materials very well.

An experienced mechanic knows how much pressure he can safely apply to various things without stripping or breaking them.

A smart mechanic will use a torque wrench when it's called for.

Most entry level cranks and BBs have to be installed with a fair amount of torque. So, unless it is some expensive, high-end components, don't worry about it: just torque the hell out of it and you will be fine.

i would recommend a torque wrench for any press fit application. sq taper, octalink, isis and others. if not put it on pretty tight. 35ftlb is a good number. so 6 inch wrench 70lbs at the end of the wrench or 1ft wrench 35lbs on the end of it

Yes. Feel is never reliable.

Both the mechanics that work at my LBS (Both pro wrenches for 30+ years) Never pick up a torque wrench unless their working on high end components, never had a problem with any of their work, not to say you should go and torque down your crankset willy nilly without knowing what your doing, thats a bad idea.

torque
 

every bb gets torqued from me.

External BB, I think is a little higher priority. Yes.

I recently got a new bike and it's got all this new stuff (to me) and I felt the need for a torque wrench to work on it and not mess it up. I was thinking about a Park wrench. My LBS (I like to spread my business around town if I can but I ain't rich) quoted me $125 but for me $110. I thought about it. My brother in law started talking about Harbor Frieght and their mix of trash and treasures. We have a local store so I checked them out. I found http://www.harborfreight.com/cpi/cta...temnumber=2696. Seems to work. Fortunately I had picked up some metric allen and star keys that fit a 1/4 socket so I was fixed for the bits.

I have one of those. It's great for things like carbon seatposts and steerers but it won't help you for a BB. That requires much higher torque than that wrench will show.

Tighten until you hear a large cracking noise then back off 1/4 turn.

You can get bigger versions of those that do higher torques. I have one that has a 3/8 inch drive that does 5-80 foot pounds or 60 to 960 inch pounds. I paid around $100 Australian for each of them, which is near enough to $100 US each.

I use them all the time. It's very little extra effort over a normal spanner / socket, and is much cheaper than the consequences - most parts on the bike that'd be ruined by over-torquing will cost me way more to replace than what I paid for those tools.

The only thing I haven't got around to getting are some "crows feet" - open ended spanner attachments with a socket in them that you can use with a socket wrench.

I never used to tighten any crank bolts tight enough for fear of stripping something, the cranks would always creak. Now I always use a torque wrench.

The funny thing is that the more you use a torque wrench the more tuned your memory and muscles get and the less you find you need it. Regular mechanics do it often enough that they know how much to torque most stuff by feel. But they also know enough to use a torque wrench on the really fussy stuff. This also assumes that they are doing it regularly so they maintain the feel.

For new or infrequent home mechanics it's not a bad idea at all to get one and use it regularly when in doubt.

Got $20? Buy a torque wrench and a happy meal. They're not expensive.



Well, they can be. But the cheapies are fine for your purposes.

Don't pay a ton of money, in tests I've seen the cheaper units are on a par with very expensive for accuracy.
bill

That wrench is WAY too big for use on carbon components. Get one of the little ones from Performance for the low torque stuff.

Don't remember knowing about torque wrenches when I did my first square taper BB in the '70's; have installed enough since then to develop a pretty good feel for it. But..........I made sure to use a torque wrench when I installed an ISIS BB and will use one when it comes time to service my current external bearing BBs.

Have the bottom-bracket faced at a reputable shop. Have them install it. Doing this without a torque-wrench yourself? That's playing Russian-Roulette. Don't.

Or just buy a torque-wrench. It won't bite.

Go to Autozone and rent one.

The Park Tool beam-type torque wrenches are a better value than the clickers if you need to watch your spending (edit: or the Craftsman-branded equivalent). If you don't use a torque wrench, the bike will definitely catch fire & explode, like when cars touch eachother in a proper '80s action TV show.

I bit the bullet and bought the Park torque wrench. I think it was between $50 and $75.

I ride longer distances with more confidence.

20 inch pounds = 2.5969658 newton meters. Since 3 Nm was the lowest limit I had on my Bianchi, I thought that was fine.

BCRiders comment to the effect that "the more you use it the less you need it" is accurate. For a new and inexperienced mechanic a torque wrench is a great learning tool. There is a general rule that inexperienced mechanics tend to over torque small fasteners and under torque large ones. A torque wrench protects the small stuff and properly tightens the big stuff.

Crank arms on square taper and Octalink/ISIS spindles require WAY more torque than most new mechanics believe. As an illustration, tighten them VERY tight with an ordinary wrench and then be astounded how much tighter you make them when you use the torque wrench.

We get almost weekly threads saying "my crank arm got loose and nearly fell off while I was riding. What should I do?" Answer: you should have installed it correctly the first time.

In a study, it was noted that most external BB's that were put on by people who didn't use a toque-wrench - inexperienced people that is - on average tightened them to 200 i.p. The correct torque is in the range of 350 - 450 i.p.

A Craftsman (SEARS) beam-type torque-wrench works fine.