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#1
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Torque wrench for BBs
I was wondering whether anyone might recommend a torque wrench for fitting
bottom brackets? I believe that the cartridge body screws in from the drive side which is a lefthand thread. The torque wrench that I have isn't reversible. Are Halford wrenches reversible? Also, do I really need a torque wrench for this job? Can the BB or BB shell be damaged by being too loose? I'm pretty new to bike maintainence and no good at guaging torque values by hand. Thanks, Paul |
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#2
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Torque wrench for BBs
Paul Davis wrote:
I was wondering whether anyone might recommend a torque wrench for fitting bottom brackets? I believe that the cartridge body screws in from the drive side which is a lefthand thread. The torque wrench that I have isn't reversible. Are Halford wrenches reversible? Also, do I really need a torque wrench for this job? Can the BB or BB shell be damaged by being too loose? I'm pretty new to bike maintainence and no good at guaging torque values by hand. Unless you've got a very unusual cartridge BB (*), then just put it in, and turn the spanner until it feels "fairly tight". I'd call that a moderate push on an 8-10 inch spanner handle. Not a big heave (too tight), and not finger tight (too loose). You don't need a torque wrench for this job (+). (* ie. not your usual Shimano / Campag off the shelf stuff ) (+ I've never used a torque wrench on a bicycle, inspite of owning two, knowing how to use them and having a passing understanding of mechanical engineering precision. I suppose there might be a use somewhere in a disc brake assembly?) . - Nigel -- NC - Webmaster for http://www.2mm.org.uk/ Replies to newsgroup postings to the newsgroup please. |
#3
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Torque wrench for BBs
in message , Paul Davis
') wrote: I was wondering whether anyone might recommend a torque wrench for fitting bottom brackets? I believe that the cartridge body screws in from the drive side which is a lefthand thread. The torque wrench that I have isn't reversible. Are Halford wrenches reversible? Also, do I really need a torque wrench for this job? Can the BB or BB shell be damaged by being too loose? I'm pretty new to bike maintainence and no good at guaging torque values by hand. You don't need a torque wrench to put a bottom bracket in, nor to do most other jobs in bicycle maintenance. Obviously, don't overtighten things particularly where they are threaded into aluminium. A bit of copper grease helps when you are putting steel parts into aluminium, just to be sure you can get it out again. But otherwise, just use common sense. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; "If I were a Microsoft Public Relations person, I would probably ;; be sobbing on a desk right now" -- Rob Miller, editor, /. |
#4
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Torque wrench for BBs
Paul Davis wrote:
I was wondering whether anyone might recommend a torque wrench for fitting bottom brackets? I believe that the cartridge body screws in from the drive side which is a lefthand thread. The torque wrench that I have isn't reversible. Are Halford wrenches reversible? Also, do I really need a torque wrench for this job? Can the BB or BB shell be damaged by being too loose? I'm pretty new to bike maintainence and no good at guaging torque values by hand. Just screw it in until it stops! |
#5
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Torque wrench for BBs
in message , Getronics Wang
') wrote: "Zog The Undeniable" wrote in message news:4116447e.0@entanet... Just screw it in until it stops! Problem is you really should tighten the cranks back on with a torque wrench or you could have problems in a short while, clicking etc resulting in wear. You must be extraordinarily heavy handed with a spanner. I've never used a torque wrench on a bike in my life, and never had any problems of the sort. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ 'graveyards are full of indispensable people' |
#6
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Torque wrench for BBs
"Zog The Undeniable" wrote in message news:4116447e.0@entanet... Paul Davis wrote: I was wondering whether anyone might recommend a torque wrench for fitting bottom brackets? I believe that the cartridge body screws in from the drive side which is a lefthand thread. The torque wrench that I have isn't reversible. Are Halford wrenches reversible? Also, do I really need a torque wrench for this job? Can the BB or BB shell be damaged by being too loose? I'm pretty new to bike maintainence and no good at guaging torque values by hand. Just screw it in until it stops! Problem is you really should tighten the cranks back on with a torque wrench or you could have problems in a short while, clicking etc resulting in wear. KC |
#7
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Torque wrench for BBs
Simon Brooke wrote:
in message , Getronics Wang ') wrote: Problem is you really should tighten the cranks back on with a torque wrench or you could have problems in a short while, clicking etc resulting in wear. You must be extraordinarily heavy handed with a spanner. I've never used a torque wrench on a bike in my life, and never had any problems of the sort. Or light handed, I guess KC might have meant. It's perfectly reasonable to use a torque wrench for this particular job unless one is already experienced enough to know when the cranks are pushed on far enough by feel (or measuring?). ~PB |
#8
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Torque wrench for BBs
"Simon Brooke" wrote in message ... in message , Getronics Wang ') wrote: "Zog The Undeniable" wrote in message news:4116447e.0@entanet... Just screw it in until it stops! Problem is you really should tighten the cranks back on with a torque wrench or you could have problems in a short while, clicking etc resulting in wear. You must be extraordinarily heavy handed with a spanner. I've never used a torque wrench on a bike in my life, and never had any problems of the sort. Likelihood is of under tightened crank bolts. Stripped threads are possible if torque wrench settings are exceeded. Few people have a calibrated forearm. Crank bolts are the only place on a bike I see the need for a torque wrench. KC |
#9
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Torque wrench for BBs
Unless you've got a very unusual cartridge BB (*), then just put it in, and
turn the spanner until it feels "fairly tight". I'd call that a moderate push on an 8-10 inch spanner handle. Not a big heave (too tight), and not finger tight (too loose). I'd say that your vague description is a fairly good argument in favour of the precision of a torque wrench. Especially since I don't think that the correct figure of around 500 in-lb for a cartridge BB (sorry, don't remember the Nm multiplier) equates to 50lb on a 10" spanner, which I would not describe as "fairly tight" or "moderate" (but maybe I am just feeble). I always use torque wrenches (Park PW-3 & PW-4, sadly no longer available) when working on my bikes. I am often surprised at how much tighter or looser the manufacturers' recommended settings are than I would have chosen by instinct alone. -- Peter Headland |
#10
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Torque wrench for BBs
You don't need a torque wrench to put a bottom bracket in, nor to do
most other jobs in bicycle maintenance. Obviously, don't overtighten things particularly where they are threaded into aluminium. A bit of copper grease helps when you are putting steel parts into aluminium, just to be sure you can get it out again. But otherwise, just use common sense. Cobblers! After much practice (and with probably some innate aptitude), you have developed a "feel" for this. You choose to forget all of that and describe your acquired skill as as "common sense"? I'll bet that, if we checked your bikes, we would find you are well outside the manufacturer's recommended torque on any number of the fasteners to which you have applied your magical common sense. Fortunately, these things tend to have a wide safety margin. The OP claims to have no feel for judging these things. I don't call it "common sense" to perform safety-critical work on a bicycle (not the BB, but stuff like brake cable pinch bolts) if you have no feel for too loose (so the cable slips and you lose your brakes at a critical moment) or too tight (so the thread strips or the bolt breaks and you lose your brakes at a critical moment). -- Peter Headland |
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