Bottom Bracket Question
#1
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Bottom Bracket Question
Ok, I currently have a TruVativ Elita triple with ISIS bottom bracket. The left crankarm keeps coming loose so I want to replace the crank. I have a 9 speed with Shimano 105 front deraileur and ultegra rear. I can pick up an inexpensive 105 triple crank, (5505) for less than $100. What bottom bracket do I need for this? I was thinking of going with an Ultegra crank but I didn't want to change anything else. I just want a decent 9 speed crank that won't fail me.
I see a 5500 bottom bracket online for around $35 but it doesn't look like it has the outboard bearing cups like my current setup??
Thanks for your help.
I see a 5500 bottom bracket online for around $35 but it doesn't look like it has the outboard bearing cups like my current setup??
Thanks for your help.
#2
Senior Member
An ISIS bottom bracket does not use outboard/external bearing cups. It is a cartridge bottom bracket just like square taper.
The 5500 series crankset would use an Octalink bottom bracket which is the cartridge type. The 5600 series cranksets use the external bearing cups.
The 5500 series crankset would use an Octalink bottom bracket which is the cartridge type. The 5600 series cranksets use the external bearing cups.
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FYI - I have the Giga X pipe bottom bracket. Maybe I should just find another TruVativ crank so I don't need to change anything?
#4
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Ok, that makes more sense now.
How many miles are on the current bearings? Are they still smooth? If they are worn at all, I would not let them influence your crankset decision.
How many miles are on the current bearings? Are they still smooth? If they are worn at all, I would not let them influence your crankset decision.
#7
Senior Member
It's your call then. You'll save some money likely by sticking with Truvativ. Lots of people swear by Shimano's cranks though.
#9
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I don't have any experience with Octalink BB's but ISIS (of the same era) has served me well.
#10
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I wouldn't say Octalink is old school. Crank systems went to integrated spindles (spindles that are part of the crankset rather than part of the BB) a few years ago but cartridge BBs like octalink and ISIS are still very common and readily available. Octalink and ISIS basically work on the same principle, they use a splined spindle; Octalink has 8 splines (hence the Octa) and ISIS has 10.
As for your problem, before changing cranksets, have you considered that the problem might be a loose or insufficiently torqued crank bolt? Try changing the crank bolt, then get yourself a torque wrernch and make sure you torque the bolt to specs to ensure the crank on is fully seated onto the spindle.
As for your problem, before changing cranksets, have you considered that the problem might be a loose or insufficiently torqued crank bolt? Try changing the crank bolt, then get yourself a torque wrernch and make sure you torque the bolt to specs to ensure the crank on is fully seated onto the spindle.
Last edited by DOS; 02-06-09 at 09:01 PM.
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I have been torque wrenching that bolt for the last part of a year. I checked it everytime after a ride and it was good. I went on a 500 mile week long tour and left the torque wrench at home, the bolt came loose on day four and left me stranded along the road.
#12
Senior Member
If you are torqueing to specs -- and for Truvativ crank bolt, thats like 400 inch pounds -- and it appears the crank arm is seating properly onto the spindle splines (shouldn't be any spindle visible bewteen inside of crank and the face of the BBshell) then I would think the problem is either the bolt itself (cheap to replace), or the threads inside the BB spindle (need a new BB), rather than the crank arm.
#13
Senior Member
Well, once the arm has come loose, the internal splines on the arm are likely ruined. Once that precise fit is gone, there's little hope that the crank arm will stay tight (just like a loose arm on a square taper spindle).
#14
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Having just installed a Shimano Hollowtech outboard bottom-bracket, I'm sure they will replace ISIS and Octalink. They are simpler, and the light-weight of the two small sealed-bearings that rotate make them much more efficient - as well as smoother. Two small sealed-bearing disks v. a much heavier metal shaft that revolves? No brainer. Installation was all of 5 minutes.
They are certain to replace the heavier, clunkier ISIS/Octalink sealed-bearing BB's that were all the rage a few years back.
They are certain to replace the heavier, clunkier ISIS/Octalink sealed-bearing BB's that were all the rage a few years back.
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I had (past tense, it's in the junk box now) an Elita GXP triple like yours, they are notorious for loosening. Giga X pipe relies on the same bolt to mate the splines and preload the bearings. So if your BB is just a little wider than 68 you won't get good spline mating. Newer versions do the preload with a spring washer, but I think it's still inferior to the Shimano outboard system which preloads the bearings with one bolt and clamps the splines with another.
#17
Senior Member
Having just installed a Shimano Hollowtech outboard bottom-bracket, I'm sure they will replace ISIS and Octalink. They are simpler, and the light-weight of the two small sealed-bearings that rotate make them much more efficient - as well as smoother. Two small sealed-bearing disks v. a much heavier metal shaft that revolves? No brainer. Installation was all of 5 minutes.
They are certain to replace the heavier, clunkier ISIS/Octalink sealed-bearing BB's that were all the rage a few years back.
They are certain to replace the heavier, clunkier ISIS/Octalink sealed-bearing BB's that were all the rage a few years back.