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new bottom backet

Old 09-05-20, 12:34 PM
  #1  
kombiguy
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new bottom backet

Hi! I have a Surly LHT. In the specs, all it say is that the BB is Shimano BSA. It is a Sora group on the bike.
I want to use an Orange Velo triple on the bike, but it tells me to pick a spindle length, while suggesting 124mm is appropriate fo most bikes.
What do I measure, and how, to determine the spindle length I need?
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Old 09-05-20, 01:08 PM
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SurferRosa
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If it's a square taper spindle, it is measured with a digital caliper from the end of one taper to the other.
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Old 09-05-20, 01:10 PM
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Going from hollowtech II of the Sora to older style JIS square tapers is going to take some dectective work for finding out what length spindle you need. Or are your current cranks old enough to be JIS square tapers?

Spindle length is simply the length of the spindle from end to end. Important for 3 piece cranks but unimportant for 2 piece cranks like modern hollowtech II cranks. So that is why I say you are going to have to do some detective work and figure out or find information on chainlines that velo crank will give you on what spindle length and compare that to what the chain line actually is currently.

You can measure chainline just by measuring from the center of your seat tube to the center between your big and small chain wheels. Might find a spec for it, but that measure has become less important too today.
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Old 09-06-20, 08:15 AM
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Try contacting Velo Orange as may have the answer for you.
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Old 09-06-20, 08:42 AM
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You know 124mm will work.
Chain line is obsessed about.
It basically means that if for example, you had a 3X9 set up, when on the middle ring, the chain would run perfectly straight when in the middle cog (5).
That depends to some extent on what the rear DO spacing is.
It would be about 2.5mm more on a 135mm spaced bike then a 130mm spaced bike.
Your spindle length must also place the rings in a position where the FDER can span all 3 without issue.

Then there's reality.
For example, I do most my riding on the middle and gears 6-8 on my 9 speed bikes.
I use a slightly wider chain line so that the chain runs "straighter" on the cogs I use most. Not some "magic number".

IF the crank is designed for a 130mm spaced bike and yours is 135, you;d want a slightly longer spindle. (2.5mm on the DS)
Not all spindles are exactly symmetrical. Another fly in the ointment.
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Old 09-06-20, 09:05 AM
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alcjphil
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Originally Posted by Bill Kapaun
You know 124mm will work.
Chain line is obsessed about.
It basically means that if for example, you had a 3X9 set up, when on the middle ring, the chain would run perfectly straight when in the middle cog (5).
That depends to some extent on what the rear DO spacing is.
It would be about 2.5mm more on a 135mm spaced bike then a 130mm spaced bike.
Your spindle length must also place the rings in a position where the FDER can span all 3 without issue.

Then there's reality.
For example, I do most my riding on the middle and gears 6-8 on my 9 speed bikes.
I use a slightly wider chain line so that the chain runs "straighter" on the cogs I use most. Not some "magic number".

IF the crank is designed for a 130mm spaced bike and yours is 135, you;d want a slightly longer spindle. (2.5mm on the DS)
Not all spindles are exactly symmetrical. Another fly in the ointment.
All this is great advice. Pay attention to it
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Old 09-06-20, 11:12 AM
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crank arm profile differences make pairing spindle length far from universal ..
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Old 09-12-20, 03:21 PM
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kombiguy
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New BB and crankset fit and work fine. And, they look great. Very classic and retro.
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