To torque or not to torque

Ace_rimmer1 said:

I just started fitting my hollowtech II crankset and the instructions talk about tightening to a specific torque setting, do you guys use a torque wrench or just give it a tug to tighten it.

Cheers
Ace

Sometimes one measurement is worth a thousand guesses. I use a torque wrench whe I work on cranks and bottom brackets and I check my speedometer when I drive through school districts.

I find no need for one. The whole concept behind the torque wrench is flawed, since it basically measures the "friction" on the bolt. What you really need to measure is the amound the bolt is being stretched, which is the only thing that keeps the part tight. Also most torque wrenches are very inaccurate, and too many variables affect them.

I just use a little common sense, and with carbon I just tighten it a bit less. One way to check how evenly I tightened two bolts or more, is by using a credit card. I slide the card through the slit in the stem, and see how close the sides are for the two bolts. Basically using it as a feeler guage.

The human hand and brain is a lot better of a torque wrench!

- I understand somewhat the need to use torque wrenches to tighten engine blocks up, and other car parts, but bikes........

free_rideman said:

I find no need for one. The whole concept behind the torque wrench is flawed, since it basically measures the "friction" on the bolt. What you really need to measure is the amound the bolt is being stretched, .....

Sorry, but your information is flawed. 😠 Lubrication of a bolt when inserting gives a more accurate torque reading, as less friction allows the wrench to measure JUST the torque for creating the stretch.

An inaccurate torque wrench is still better that a guess. That's why manufacture gives a torque specification instead of "snug it until you think its ok"

If you are going to work on you bike, buy the right tools! And a torque wrench is not that costly. Better than a crank coming off or cracking.

Okay, I guess its whatever floats your boat kind of thing. I for one have never had a problem not using torque wrench.

Sorry, but even if you do grease the bolt, it still might have friction. Not all companies make perfect threads.

It does not come down to choice. In quality checks on bikes it has been found that mechanics routinely tighten things down way over the torque spec. Torque wrenches are a lot more accurate than a human, "feel." Granted, there is a lot of margin in torque for a lot of fasteners, but on notch-sensitive carbon, only an idiot would trust their own sense of feel.

wow... "the human brain and hand is better than any torque wrench"...

i just dont know what to say to that.

after wrenching for 11 years on GP motorcycles... i can only say that a torque wrench is your best friend.... and nobody in any professional capacity uses the "hand" method.

accept maybe the butt-crack showing shade tree mecho that fixes the local lawn mowers.

now, i'll concede that bicycles might not require the surgical level of mechanics of motorsports...

but i will say that when i spend high bucks on my bike, i dont want things to crack (too tight) and i dont want things to wobble (too loose)

i torque.

and for those real low (bicycle-level) torque settings that maybe too low for a small (1/4"😉 torque wrench...

check out these bad boys...

buy1.snapon.comitem.aspOpen ↗

enjoy.

Ok, so what torque wrenches would you people recommend...

- the snap-on (@ USD 160-odd) as per schmuzzy;
- the syntace tourque tool (around 110 Euro);
- ????

Thanks.

So how do I get a torque wrench on this, I ain't gonna buy one that I'll use 2 or 3 times so I was gonna try and hire one but how will I measure the torque using this BB spanner, I assume there must be a unit that fits over the handle or something like that.

[img]probikekit.comX0013.jpgOpen ↗[/img]
Cheers
Ace

Edit: are there any other tools that can be used to get the torque setting sudgested by shimano for the bottom bracket, maybe a socket that would fit the HT II BB that can be used with a torque wrench.

Okay, all you people are way to hostile. Let me say this in a different way.

When working on big parts, in cars, motorcycles or whatever, there is more sense to use a torque wrench. For one the metals are thicker, and more consistent. In those situations I can see the reason for using a torque wrench, and sometimes you do need a very accurate setting in those applications. For example, you want the engine head to be tight enough so that there is no oil leaking, or any pressure loss.

But I just don't see the reason for buying a torque wrench for a bike. First the parts are so simple and sometimes so "small" that you can guess using your hands. I never overtighten anything and with bike parts, I have found that every part needs its own special attention, instead of just using a torque setting for all of the same thing. I use my brain a little, instead of just spending $60 plus dollars for torque wrenches. I know many people, including myself, that don't use torque wrenches, and haven't had any problems.

So clearly torque wrenches aren't the only way of tightening up bolts. I am fine with people using them, just don't make it seem that it is the only way.

-another thing is torque wrenches are sometimes used to ensure that all bolts have equal torque applied. Well I just use a feeler guage for this (credit card).

Here's why I think that using torque wrenches on bicycles is a good idea.

You don't have to do much shop work before you have somebody bring in a bike that has a hosed left crankarm. The only possible cause for that is inadequate crankarm bolt torque. The torque spec for that particular fastener is around 30-35 ft/lbs. That's more than you are likely to be able to get using a 6 inch long allen wrench and it's more than I would use if left to my "mechanic's feel".

If you work on upper end bikes for awhile, you will find somebody who has ruined a high dollar stem by overtorquing the bolts. If I remember right, the torque spec. for all of the bolts on my Thompson stem is 45 in/lbs. That's scarcely anything at all. If left to my "mechanic's feel" I'd definitely overcook them.

I think that it's more professional to use a torque wrench than an educated guess. If you work on bicycles professionally, you'll need two because the torque requirements vary so much: I use a 3/8 drive for cranks and bottom brackets and a 1/4 drive for stems.

Retro Grouch said:

I use a 3/8 drive for cranks and bottom brackets and a 1/4 drive for stems.

Right, so how can I torque the BB of the hollowtech II when there are no other tools except the Shimano and they don't do a torque wrench for this although they quote 35-50 Nm, if I can't get a torque wrench, should I just tighten this as hard as I can (LBS quote, pull it as hard as you can, it's very rigid and won't break).

I'm worried about the torque settings cos last time I tighned something without a torque wrench (water pump from a Ford Cortina, long time ago) I cracked the pump and had a worse leak than I had before and don't fancy knackering £70 worth of crackset.

No problem for the other bolts, this is just allen and I'll have a torque wrench for that it's just the BB i'm not to sure on

Cheers
ace

Ace_rimmer1 said:

Right, so how can I torque the BB of the hollowtech II when there are no other tools except the Shimano and they don't do a torque wrench for this although they quote 35-50 Nm, if I can't get a torque wrench, should I just tighten this as hard as I can (LBS quote, pull it as hard as you can, it's very rigid and won't break).

I'm worried about the torque settings cos last time I tighned something without a torque wrench (water pump from a Ford Cortina, long time ago) I cracked the pump and had a worse leak than I had before and don't fancy knackering £70 worth of crackset.

No problem for the other bolts, this is just allen and I'll have a torque wrench for that it's just the BB i'm not to sure on

Cheers
ace

Without getting into the debate.... They do make a 1/2" drive socket version (part# TL-FC33) which can be used with a torque wrench:

see:
bike.shimano.commultiproduct.jspOpen ↗

http://www.wiggle.co.uk/Default.aspx?Main=ProductDetail.aspx&W=0&Manufacturer=Shimano&UberCatName=&Cat=cycle&CategoryName=&ProdID=5360016481&UberCat=0

There is also a discussion on the subject at:
bikeforums.nett 180751.htmlOpen ↗

using a torque wrench is a personal deciscion based on skill, expirience and common sense. you think the guy leaning out of the team support car has a torque wrench in his hand as he raises the saddle on boonen's spare bike at 50 kph? no way.

i've built high end racing bikes for myself and friends for over 30 years.

i've never used a torque wrench on any fastener on a bike. never stripped any fastener and never had and any fastener back out or leave pieces parts on the road.

and it has nothing to do with luck.

ask some questions, use your head for something other than a hatrack and you'll do just fine.

oh...and invest in several grades of loctite. wonderful stuff.

now, i will admit this new 'carbon era' components are a bit more tricky. still, common sense rules the day.

i'll save my torque wrenches for my harley-davidson cylinder head bolts and my anschutz match rifle action screws.

regards,
campybob

thanks! My point clearly. So it really depends on the person. The only reason why I was pressing this issue was the fact there are two ways of doing it, the torque wrench way, and the hand way.

Retro Grouch said:

Here's why I think that using torque wrenches on bicycles is a good idea.

You don't have to do much shop work before you have somebody bring in a bike that has a hosed left crankarm. The only possible cause for that is inadequate crankarm bolt torque. The torque spec for that particular fastener is around 30-35 ft/lbs. That's more than you are likely to be able to get using a 6 inch long allen wrench and it's more than I would use if left to my "mechanic's feel".

If you work on upper end bikes for awhile, you will find somebody who has ruined a high dollar stem by overtorquing the bolts. If I remember right, the torque spec. for all of the bolts on my Thompson stem is 45 in/lbs. That's scarcely anything at all. If left to my "mechanic's feel" I'd definitely overcook them.

I think that it's more professional to use a torque wrench than an educated guess. If you work on bicycles professionally, you'll need two because the torque requirements vary so much: I use a 3/8 drive for cranks and bottom brackets and a 1/4 drive for stems.

Just for a note, I have a thomson stem, and I tightened it by hand, and this is with a carbon steerer. Not trying to pick a fight, just to show that is is possible. (yes the thomson stems are easy to tighten, I love them!) For the crank arms, I see your point! Respectfully, I will still do it my way.

i've watched guys in white coats botch an engine rebuild with the manual in one hand and a torque wrench in the other.

i've also seen engines rebuilt on a chain while hanging from an oak tree that ran 100,000+ hard miles, trouble free.

torque specs aren't the be-all and end-all, but they ARE there for a reason. some folks need that audible click and some folks don't. some jobs require a torque wrench and some jobs don't.

expirience soon teaches you 'which' is 'what'.

regards,
campybob

serenaslu said:

Without getting into the debate.... They do make a 1/2" drive socket version (part# TL-FC33) which can be used with a torque wrench:

see:
bike.shimano.commultiproduct.jspOpen ↗

wiggle.co.ukDefault.aspxOpen ↗

There is also a discussion on the subject at:
bikeforums.nett 180751.htmlOpen ↗

Thank you, I been looking for ages trying to find this socket and even the LBS said they don't exist, if the BB was a little more robust I would leave it as done by hand but as it feels like it'd break if you blew on it, as the tool is available I might as well use it.

It'll be nice to see if I have over or under tightend it, I'll post when I get the socket.

Cheers all
Ace

Ace_rimmer1 said:

Thank you, I been looking for ages trying to find this socket and even the LBS said they don't exist, if the BB was a little more robust I would leave it as done by hand but as it feels like it'd break if you blew on it, as the tool is available I might as well use it.

Well, then there's always this:

The torque spec for bottom brackets is usually around 30 or 35 ft/lbs. Imagine a 30 pound weight hanging off of the very end of a foot long wrench. Tighten it that much. If you only have a 6 inch wrench, you need to imagine a 60 lb weight.

Like I've said, I have them, I use them, and I think that using one is more professional. But just because you don't have access to a torque wrench doesn't mean that you have to completely ignore the spec. Think about what ft/lbs means and think about what you're doing and I suspect that you will generally get pretty close.

[quote="Retro Grouch"]
. Imagine a 30 pound weight hanging off of the very end of a foot long wrench. Tighten it that much. If you only have a 6 inch wrench, you need to imagine a 60 lb weight.

QUOTE]


I do it that way too. You can actually go as far as hang an actual weight off the end of your wrench. Use half the weight if your lever is 2 feet long and 2x the weight if the lever is 6 inches long. Or use a spring loaded scale so you can pull in any direction. the force applied should be at 90 degree angle to the lever.

I have stripped threads on my bikes and motorcycles in the past and had nuts and boots come loose too, you learn by experience. i now prefer to err on the side of having it a bit loose than too tight.

Good advice?: don't work on other people's bikes without a torque wrench...

USA (elsewhere?) bike mechanics should torque because of liability and use a checklist! people love to sue you in the USA! and you'll want documentation...

without proper grease the torque reading means almost nothing...

millions of bike racers have done their own maintenance without a torque wrench... successfully, plenty have had failures, often chocked up to 'bad parts' we don't have the data...

if i have a choice i use the torque wrench esp. cranks, extreme overtightening could mean failure, long term overtightening (repeated mounting and removal) may lose product life, undertightening loss of other life! hehe

EVER HEARD THIS ONE?

poor racer's guide: tighten your stem, handlebars, seat to the point where it will break loose in a crash... saves the part, you WILL be in a pile-up sometime... HEHE

probably was ok back in the days before exotic materials...

all's'miles

curby