fadetoblack6902
09-18-06, 09:31 PM
I am trying to build a fixed gear. How do you adjust the bb axle?
thanks in advance
thanks in advance
Bicycle Mechanics - how to move bb axle, for fixed gear.
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moxfyre
09-19-06, 08:54 AM
Adjust the BB axle... what do you mean? Are you trying to clean and regrease it? Are you trying to move it side to side (adjust the chainline)?
fadetoblack6902
09-19-06, 08:56 AM
I am trying to move it from side to side to adjust chainline. It is a nonsealed 3 piece bb
moxfyre
09-19-06, 09:00 AM
I am trying to move it from side to side to adjust chainline. It is a nonsealed 3 piece bb
Ah, okay. Well, unfortunately, there's basically only one bit of side-to-side adjustment that you can do with a standard cup-and-cone BB: you can remove the spindle and flip it around. That will typically move the chainrings 5 mm closer to the frame, and of course it will move the left crank 5 mm further away too.
If you need to adjust the chainline precisely, you'll probably have to get a new BB spindle (cheap these days, most LBSes would probably give you one for $5 or something). The other option is to get a spacer which sits in between the BB cup and the frame on the right side... but that will only allow you to move the chainrings further OUT, not further IN.
Ah, okay. Well, unfortunately, there's basically only one bit of side-to-side adjustment that you can do with a standard cup-and-cone BB: you can remove the spindle and flip it around. That will typically move the chainrings 5 mm closer to the frame, and of course it will move the left crank 5 mm further away too.
If you need to adjust the chainline precisely, you'll probably have to get a new BB spindle (cheap these days, most LBSes would probably give you one for $5 or something). The other option is to get a spacer which sits in between the BB cup and the frame on the right side... but that will only allow you to move the chainrings further OUT, not further IN.
fadetoblack6902
09-19-06, 09:02 AM
thanks, i'll try a spacer. I only need to move the chainwheel slightly to the right.
moxfyre
09-19-06, 09:04 AM
thanks, i'll try a spacer. I only need to move the chainwheel slightly to the right.
Sounds good. If the change you're talking about is 1 mm or so... you can flip the chainring over :) Most chainrings have the teeth slightly off-center, allowing you to change their position by flipping the ring.
Sounds good. If the change you're talking about is 1 mm or so... you can flip the chainring over :) Most chainrings have the teeth slightly off-center, allowing you to change their position by flipping the ring.
fadetoblack6902
09-19-06, 09:05 AM
I think it may need a bit more than that. What do you recommend using as a spacer?
Rowan
09-19-06, 09:08 AM
thanks, i'll try a spacer. I only need to move the chainwheel slightly to the right.
The one problem in adding a spacer on the driver side with a cup-and-cone system is ensuring you still have enough thread on the adjustable cone on the left side to fit the lockring. If you can't thread on the lockring with at least two threads, your adjustment won't work.
The one problem in adding a spacer on the driver side with a cup-and-cone system is ensuring you still have enough thread on the adjustable cone on the left side to fit the lockring. If you can't thread on the lockring with at least two threads, your adjustment won't work.
moxfyre
09-19-06, 09:16 AM
I think it may need a bit more than that. What do you recommend using as a spacer?
You can buy a BB spacer from www.loosescrews.com for about $1. Do note Rowan's point: if you have to move the BB more than a couple mm to the right, you'll likely not have enough adjustable cup threads sticking out on the left side to secure the lockring to. Personally, I would probably just by a $15 cartridge BB from Nashbar at that point :)
I'm a bit surprised that you have to move the chainrings AWAY from the frame. With most converted fixies, I find that the chainrings need to be moved CLOSER to the frame to match up with the chainline of typical track cranks.
You can buy a BB spacer from www.loosescrews.com for about $1. Do note Rowan's point: if you have to move the BB more than a couple mm to the right, you'll likely not have enough adjustable cup threads sticking out on the left side to secure the lockring to. Personally, I would probably just by a $15 cartridge BB from Nashbar at that point :)
I'm a bit surprised that you have to move the chainrings AWAY from the frame. With most converted fixies, I find that the chainrings need to be moved CLOSER to the frame to match up with the chainline of typical track cranks.