# my SOMA Hellyer cranks



## DIRT BOY (Aug 22, 2002)

I like them!


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## Dave Hickey (Jan 27, 2002)

Me too......Very cool looking.. What length BB do they require?


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## DIRT BOY (Aug 22, 2002)

Dave Hickey said:


> Me too......Very cool looking.. What length BB do they require?


I am using a 108mm right now.

My 103 Sugino did not work. The inner bolts would scrape the chainstay. 108 seems just about as close as I can get.

If you ever need/want, let me know. BYW, they use the 144mm track bolt pattern


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## PlasticMotif (Aug 1, 2006)

That's a pretty nice looking crank.


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## Dave Hickey (Jan 27, 2002)

DIRT BOY said:


> If you ever need/want, let me know.


I might do that ....thanks


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## ukiahb (Jan 26, 2003)

loooks great! so is it reasonably round too? (i.e. chain tension doesn't vary with crank position)


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## DIRT BOY (Aug 22, 2002)

ukiahb said:


> loooks great! so is it reasonably round too? (i.e. chain tension doesn't vary with crank position)


Seems fine to me. When turning the cranks i the stand, I don't see any sag in the chain.


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## ukiahb (Jan 26, 2003)

DIRT BOY said:


> Seems fine to me. When turning the cranks i the stand, I don't see any sag in the chain.


thanks, that is good to know, have had that problem when I used cranks from a geared bike before....chain would be tight is some spots and loose in others so setting the tension would be a compromise


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## dunklegelb (Sep 20, 2008)

Very Unique lookin ring!
So the the BCD is 144? Isnt Track 140 or somethin??

Yu know how to pimp it up further!? 
Check if they make anodized Chainring bolts in white or yur frame color!
They usually make BMX bolts in an assortment of colors no?
Or is that too matchy matchy? Ha!


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## Dave Hickey (Jan 27, 2002)

Standard track BCD is 144...unless you are an old Campy lover and then it's 151


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## DIRT BOY (Aug 22, 2002)

ukiahb said:


> thanks, that is good to know, have had that problem when I used cranks from a geared bike before....chain would be tight is some spots and loose in others so setting the tension would be a compromise


These are Track cranks, not geard converted.


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## CleavesF (Dec 31, 2007)

ukiahb said:


> loooks great! so is it reasonably round too? (i.e. chain tension doesn't vary with crank position)


Myth. Sheldon uses biopace on his fixies man.


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## Alx (Mar 22, 2007)

Those are sweet looking. BTW what size crank arms come with the madison?


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## DIRT BOY (Aug 22, 2002)

Alx said:


> Those are sweet looking. BTW what size crank arms come with the madison?


170mm. 

My Soma cranks are 165mm


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## ukiahb (Jan 26, 2003)

CleavesF said:


> Myth. Sheldon uses biopace on his fixies man.


wrong, NOT a myth I've actually built several fixies with road and track cranks and there is a big difference...tried biopace too and the chain tension varies a LOT...it does work but round rings work better and track cranks better still. Sheldon himself spoke (sadly he passed away this year) of having to fiddle with the chain rings on road cranks to attempt to get more consistent chain tension, maybe take another look at his fixed gear pages and read carefully...


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## ukiahb (Jan 26, 2003)

DIRT BOY said:


> These are Track cranks, not geard converted.


sorry, I got that but didn't word my remark well...what I meant was is the roundess better than a typical road crank


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## Alx (Mar 22, 2007)

So are you saying that track components are more round than road components?


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## ukiahb (Jan 26, 2003)

Alx said:


> So are you saying that track components are more round than road components?


yep, in my limited experience....it really doesn't matter on a geared bike since the dérailleur handles chain tension....but FWIW I bought a Sugino 75 crankset for my fixie and the nearly perfect roundness is great, setting chain tension is very easy, the bike runs smoother, and dropping the chain is that much less likely and hasn't happened to me yet in five years. This precision cost more to produce and is why track cranks are generally more expensive, made the original post as I was curious if the Soma crank was built to track standards, sounds like this is the case...


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## Dave Hickey (Jan 27, 2002)

ukiahb said:


> yep, in my limited experience....it really doesn't matter on a geared bike since the dérailleur handles chain tension....but FWIW I bought a Sugino 75 crankset for my fixie and the nearly perfect roundness is great, setting chain tension is very easy, the bike runs smoother, and dropping the chain is that much less likely and hasn't happened to me yet in five years. This precision cost more to produce and is why track cranks are generally more expensive, made the original post as I was curious if the Soma crank was built to track standards, sounds like this is the case...


+1...That is my experience too..my bikes that have track cranks and rings don't have to tight spots that the converted road cranks have..

That is the biggest advantage of track cranks IMHO


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## Alx (Mar 22, 2007)

I wonder why that isn't one of the key points advertised with track components for people riding in the street. Either way my sugino stuff has yet to cause me any problems but maybe I'm justifying cause I can't afford $200 for 75s or better.


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## Jesse D Smith (Jun 11, 2005)

Alx said:


> So are you saying that track components are more round than road components?


http://www.peterwhitecycles.com/fixed.asp
"The highest quality track cranksets are made to precisely center the chainring on the bottom bracket. Any out of roundness in the chainring, crank arm, or bottom bracket will lead to the tension on the chain being uneven. The problem is called runout. Cranksets with poor centering result in the ring not turning in a perfect circle, so as you turn the crank, the chain will be first tight, and then loose once each revolution.

To eliminate runout, first the bottom bracket axle must be very precisely machined, so that the four flats, the tapered end of the axle, are centered to the axis of rotation of the axle, defined by the bearing races. Then, the four flats on the crank must also be centered relative to the bolt holes for the chainring. And last, the circle defined by the five chainring bolts on the chainring must be the same circle defined by the chainring teeth. If any one part of the crankset and bottom bracket isn't perfectly centered, the chain tension cannot be consistent throughout the crank's rotation."

So when you talk about "roundness" it might be a slightly out-of-round ring, or it could be an due to an imperfection in the bottom bracket/crank interface.

When you loosen your headset and rotate your bars/stem clockwise or counterclockwise, any adjustment of only fractions of a millimeter at the stem/headset interface will result in millimeters of moment at the end of the bars. For the same reason, imperfections involving fractions of millimeters in the bottom bracket/crank interface can translate into millimeters of visible runout when viewing the ring itself. 

I have a Sugino Messenger crank (just an RD with a Messenger ring) paired to a cheap Sugino sealed bearing bottom bracket. I have noticeable runout. So all "single-speed" or fixed-gear cranks, rings and bottom brackets aren't the same. Some are just road components with some alterations.


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## ukiahb (Jan 26, 2003)

interesting!....hadn't realized the BB had a major role too, but it makes sense...FWIW am using a Phil Wood BB with a track crank and it works well, no perceptible out of roundness


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