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Old 05-21-09, 12:53 PM   #1
alfred mcdougal
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Bottom Bracket and Cranks

I know I will be using a square-taper cartridge bottom bracket. What other parts will I need to complete the connection between the bottom bracket and the cranks? There are threads on the cranks. What screws into these threads (No, not the threads where the pedals screw into)?

I have these cranks:

Sugino Model: XD2WR

http://www.suginoltd.co.jp/crank_e.html

What measurement is the 110mm distance coming from? I know that is a BCD measurement for a crank, but why is Sugino referring to a bottom bracket axle?

"B.B.Axle: 110mm Square taper"
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Old 05-21-09, 01:12 PM   #2
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The threads on the square taper cranks are for the crank removal tool. The 110mm you are asking about is the length of the bottom bracket spindle or axle. bk
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Old 05-21-09, 02:09 PM   #3
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Correct me if I'm wrong, I believe cassette style bottom bracket axles come in a 110mm verity as well as a 127mm verity. I'm tall and I would like an increased Q-factor, so I would prefer a longer axle. Could I use a 127mm axle with those cranks? Note: chain line will not be a problem because I will be using a drive train connection that involves a cassette style cog, cassette SS spacers, a freehub, and a surly singleator.

Is this safe? Has anyone done anything like this?

Thanks in advance.
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Old 05-21-09, 02:34 PM   #4
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Originally Posted by alfred mcdougal View Post
Correct me if I'm wrong, I believe cassette style bottom bracket axles come in a 110mm verity as well as a 127mm verity. I'm tall and I would like an increased Q-factor, so I would prefer a longer axle. Could I use a 127mm axle with those cranks? Note: chain line will not be a problem because I will be using a drive train connection that involves a cassette style cog, cassette SS spacers, a freehub, and a surly singleator.

Is this safe? Has anyone done anything like this?

Thanks in advance.

How wide of a Q-factor do you want?

A Sugino Xd triple with a 115 BB offers appx. 167mm Q factor. Do the math from there. If you want a 179mm Q ..... go for it. A crank connection is a crank connection, further apart make no difference.

How tall are you? Inseam? ....... You may benefit from longer cranks..... but that'll throw a wrench into your plans.


You don't sound too sure of what you're doing though, you may need some hands on help from a friendly bike shop or something.
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Old 05-21-09, 02:58 PM   #5
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How tall are you?
I'm 6'3-1/2". I've been riding 175mm cranks for a long time with no pain. I'll say this is a good sign.

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Originally Posted by Garthr View Post
How wide of a Q-factor do you want?
I like the Q-factor on my 29er, but I don't know what it is off hand. I have to measure that.

I am aware I shouldn’t go too wide or peddling through corners will be impossible. Currently, I can't peddle through most corners on my 29er, but it is not designed like a road bike anyway.

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You don't sound too sure of what you're doing though, you may need some hands on help from a friendly bike shop or something.
You're absolutely correct. I'm still researching before doing anything. I know I have details to learn. I can do this, I know I can. I simply don't want to waste money (buy the wrong sized/spec'ed parts) because I'm not considering all of the variables.

I would simply say it like you did and go from there:

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A crank connection is a crank connection
Thanks for the reply.
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Old 05-21-09, 03:02 PM   #6
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I'm unsure how height has a direct relation to Q-factor. I'm ~6'3" and on longer riders my knees appear to appreciate narrower Q-factor on cranks.

I think the more accurate anatomical trait would be width of your pelvis/hips - not how tall you are.
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Old 05-21-09, 03:09 PM   #7
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The BB spindle length has to do with getting the proper chain line. If you want a wider Q factor you need to look at the crankset and try to find one with a wider Q. I think the XD2 has a Q factor of 165 mm, which is probably sort of a medium number today. Smurf Hunter's comment is a good one - Q factor is about getting your pedals to a width that is efficient and comfortable for you, not necessarily about height or leg length.
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Old 05-21-09, 03:15 PM   #8
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It is usual to screw some kind of dust cap on to the threads.
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Old 05-22-09, 07:45 AM   #9
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Thanks
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Old 05-22-09, 08:36 AM   #10
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there is a retaining bolt that screws into the BB that holds the crank arm on.
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Old 05-22-09, 11:29 AM   #11
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You want exactly the spindle length dictated by your crankset. If you have a different length, you will have a poor chainline and consequently poor shifting. There are other fixes to Q factor; BB spindle is not one of them.

All you need in addition to the BB and the crank are bolts to hold the crank on. Sometimes they do not come with the BB, for reasons I can't imagine. Ask your LBS when you buy. Also check the BB to make sure they've given you a cup for the non-drive-side (these are often missing after mechanics pull them for other uses) and that the cup is the right size (73mm BBs have a longer cup, generally).
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Old 05-22-09, 11:41 AM   #12
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for sugino triples with MTB style bowed chainstays they recommend 110mm BB axle.
for sugino triples with road style chainstays, they recommend 110mm BB axle, but in reality you can use 107mm or less to achieve a better chainline without having any problem with the chainrings rubbing the chainstay.

110mm axle gives a pretty poor chainline on my CX bike that has a sugino XD600.
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Old 05-22-09, 11:47 AM   #13
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I found a crank puller for $2.50. I also found the bolts I need to fasten the cranks to the bottom bracket.

I'm still undecided how I will go about the over-all bike build at this time, so I am not going to buy the bottom bracket until I know everything I need to know.
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Old 05-22-09, 11:54 AM   #14
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Last edited by alfred mcdougal; 05-22-09 at 11:58 AM.
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Old 05-22-09, 11:57 AM   #15
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Quote:
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for sugino triples with MTB style bowed chainstays they recommend 110mm BB axle.
for sugino triples with road style chainstays, they recommend 110mm BB axle, but in reality you can use 107mm or less to achieve a better chainline without having any problem with the chainrings rubbing the chainstay.

110mm axle gives a pretty poor chainline on my CX bike that has a sugino XD600.
Its funny you mention this. On my Trek Soho SS (the one I am unsatisfied with and currently replacing with this build), the chain line is off by a few mm. It needs a longer BB axel. From what I can tell, the rear wheel's free wheel, can't be moved in slightly.

I've been studying my bikes for this build, its remarkable how many factors you have to compensate for.
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Old 05-22-09, 12:00 PM   #16
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The more I learn, the more I believe a 110mm BB is the correct choice.
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