Bicycle Mechanics - crankset install with no torque wrench

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bigdaddy10028
08-11-10, 11:23 AM
Am i asking for trouble if I do a crank install without a torque wrench or is this just one of those things where you are really trying to get it on really really tight? We are dealing with an aluminum frame here.
demoncyclist
08-11-10, 11:26 AM
You aren't necessarily asking for trouble. But depending on the type of crankset, you can do damage if you use too much or too little torque on the crank fixing bolt(s). I'm kinda curious why you needed to specify the frame material, as it is a moot point anyway.
superdex
08-11-10, 11:30 AM
crank or BB?
BB, make sure it's threaded right, then crank that b*tch down. Crankbolts, I'd pay attention to the directions included, but....
cny-bikeman
08-11-10, 11:31 AM
I don't think you are asking for trouble. Very, very few shops used torgue wrenches before the 90's. You don't want to overdo it - a normal length ratchet should offer a fairly decent natural limit. If you hear clicking when riding you probably need to tighten more. One idea is to see if you auto mechanic can check the torque.
bigdaddy10028
08-11-10, 12:19 PM
You aren't necessarily asking for trouble. But depending on the type of crankset, you can do damage if you use too much or too little torque on the crank fixing bolt(s). I'm kinda curious why you needed to specify the frame material, as it is a moot point anyway.
trying to do the old, give as much info as possible thing. I should have mentioned it's an isis cartridge bottom bracket and yes i'm installing that too.
fietsbob
08-11-10, 12:35 PM
If it's a New 2 piece , external BB type with Carbon Fiber arms, Yes.
Square taper or octalink 3 piece types, No. aluminum arms 2 piece maybe ,
don't over do the left arm tightening on those 2 small bolts ..
Oh Isis Spline ... probably not , a common peanut butter 15mm wrench
isn't too long so its harder to over do it ..
thin wall 15mm socket in a 3/8 drive ratchet you should be careful, not too much ..
HillRider
08-11-10, 12:41 PM
If it's a New 2 piece , external BB type with Carbon Fiber arms, Yes.
Square taper or octalink 3 piece types, No. aluminum arms 2 piece maybe ,
don't over do the left arm tightening on those 2 small bolts ..
It's an ISIS bb and crank. Torque both down hard!
bigdaddy10028
08-11-10, 12:43 PM
i'm a big strong guy, been told I should torque these down good but I'm afraid of overdoing it. it was installed 3 weeks ago on one bike, now i'm taking it out myself to put on another bike. it came out pretty easily. I think i've gotten it tightened sufficiently. what could i expect to happen if it wasn't tightened down enough?
To make sure i'm correct, you screw in the fixed side hand tight and then torque down hard the other side?
BCRider
08-11-10, 12:52 PM
Big and strong like an ox means yeah, go tight but don't make yourself grunt too hard in doing this. Putting the BB in with a regular 1/2 inch ratchet and the big spline cup means you want to pull on the end of the ratchet handle with around 40 to 50 lbs. So about two bicycles worth... :D With the crank arm bolts useing a regular L allen wrench tighten it until it leaves a mark in your fingers but not enough to actually make it seriously uncomfortable. That's about a 40 to 50 lb push again but with the shorter arm length it's about right.
I don't remember what my last ISIS BB looked like but as I recall there's the cartridge and then a plastic support sleeve for the other side. Screw in the cartridge hand tight, snug the sleeve in and then tighten the cartridge side to full torque. You don't want to be bearing down hellishly on the support sleeve side.
bigdaddy10028
08-11-10, 12:56 PM
i used a pretty long adjustable wrench for the bottom bracket, about to do the cranks now and i have a long handled 8mm wrench as well. Thanks for the help gang
fietsbob
08-11-10, 01:00 PM
ISIS will bottom out the spline interface, then you are just stretching the bolt a hair to keep it from loosening.
KDC1956
08-11-10, 02:04 PM
I would use a torque wrench my self.The park torque wrench is not that much it.I got the TW-2 for about fifty bucks it has 3/8 drive on it.I think its nice to torque it down to where it should be I have been known to rip out threads on any thing like on a chevy head so that's why I now use a torque wrench on any thing that needs it.Order one from your LBS that's what I did.My 2 cents on this matter.
bigdaddy10028
08-11-10, 02:17 PM
if i were torquing stuff down on carbon fiber i'd be more inclined to get one but for something you just need to get on there good and tight I'll trust elbow grease
davidad
08-11-10, 04:05 PM
Torque wrench is the only way to go.
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