Buying a new crankset without replacing the BB
06-27-16, 06:47 PM
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Buying a new crankset without replacing the BB
I have a slight bend in my crank arm spider that has made my FD adjustments a little bit finicky, so I'm thinking about buying a new crankset. However, I literally just bought and installed a new bottom bracket a few days ago, so I want to make sure the replacement fits that BB. Spindle length is 127mm (same as the bike's original BB). How do I go about finding a crankset? Do cranksets even require a specific spindle length?
BTW, this is a cheapo early '80s Japanese bike, so I'm trying to keep the expenses low.
BTW, this is a cheapo early '80s Japanese bike, so I'm trying to keep the expenses low.
06-27-16, 06:57 PM
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Square taper BB & crank I assume ?
You could try bending the spider to fix it.
You could try bending the spider to fix it.
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06-27-16, 07:00 PM
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Square taper, yes.
I'm looking to buy a compact double with cyclocross-ish chainring sizes, like maybe 36-46t. Trying to keep the cost under $80, and I'm open to buying vintage gear.
The bend in the spider isn't clearly visible, it just manifests itself in a 1-2mm chain wobble. I wouldn't know where to bend it back, and I'm reticent to rely on an aluminum crank arm that's been permanently bent twice.
I'm looking to buy a compact double with cyclocross-ish chainring sizes, like maybe 36-46t. Trying to keep the cost under $80, and I'm open to buying vintage gear.
The bend in the spider isn't clearly visible, it just manifests itself in a 1-2mm chain wobble. I wouldn't know where to bend it back, and I'm reticent to rely on an aluminum crank arm that's been permanently bent twice.
Last edited by destro713; 06-27-16 at 07:03 PM.
06-27-16, 07:52 PM
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Is it currently a triple? 127 is pretty wide.
06-27-16, 08:24 PM
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Buy nice or buy twice.
127 mm is really wide by modern standards. I'm thinking you are going to find it difficult to match that BB. You probably are going to have trouble getting the front derailleur to work. If it was my bike I'd bite the bullet, get the crankset that you want and whatever bottom bracket it takes to match.
127 mm is really wide by modern standards. I'm thinking you are going to find it difficult to match that BB. You probably are going to have trouble getting the front derailleur to work. If it was my bike I'd bite the bullet, get the crankset that you want and whatever bottom bracket it takes to match.
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06-28-16, 05:22 AM
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Buy nice or buy twice.
127 mm is really wide by modern standards. I'm thinking you are going to find it difficult to match that BB. You probably are going to have trouble getting the front derailleur to work. If it was my bike I'd bite the bullet, get the crankset that you want and whatever bottom bracket it takes to match.
127 mm is really wide by modern standards. I'm thinking you are going to find it difficult to match that BB. You probably are going to have trouble getting the front derailleur to work. If it was my bike I'd bite the bullet, get the crankset that you want and whatever bottom bracket it takes to match.
06-28-16, 08:22 AM
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destro713, You might try chain ring shims (thin washers) to align the rings. If the spider is bent inwards, shim the opposite chain ring bolts. If bent outwards, shim that side of the chain ring. If this straightens the chain ring, you may have to shim the inner chain ring(s) also.
Brad
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