Lightweight track crankset/bb combo

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waychel
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by waychel

Do these exist? I know that, on the track, stiffness is valued over weight. However, I ride my track bike mainly on the street, and I want a light track crank! Or a light 165 road crankset that will yield a nice chainline...

I have a Truvativ Omnium that's pretty beefy. I have the 7600 square-taper Dura-Ace track cranks, too. They're pretty light (500ish grams), but the matching bottom bracket weighs 280g. And I haven't been able to find a 109mm ti JIS bottom bracket.

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mitre_tester
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by mitre_tester

Lightest in my stable (apart from the 600g CQP titanium ones, which are brilliant but completely unavailable) is the TA Alize, which would build to about 760g complete with TA Axix Ti BB and 48t 3/32" ring
Last edited by mitre_tester on Mon Jun 21, 2010 10:47 pm, edited 1 time in total.

by Weenie


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wilmar13
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by wilmar13

I installed an FSA Carbon Superlight crank with Ti BB on that I have lying around (it is a road crank), using the inner mount for a 41.5mm chainline. I can't say I noticed any disadvantage except I didn't have rings in 130mm to give me a gear I liked so I took them back off.

It was only about 60 grams lighter than the FSA Carbon Track Pro (without rings), biggest weight loss was using the Ti BB. Maybe just getting another crank (road or track) where you have cheaper weenie BB options is what you could look into.

Irish
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by Irish

I've used Record Carbon road cranks with Miche chainrings mounted on out side on my track bike with no problems(chainline 42.5 afaik). Not sure of total weight of set-up but i'm over 220lbs.

Mile Ditch
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by Mile Ditch

Irish wrote:I've used Record Carbon road cranks with Miche chainrings mounted on out side on my track bike with no problems(chainline 42.5 afaik).
Ultratorque or the older square taper ones?

waychel
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by waychel

mitre_tester wrote:Lightest in my stable (apart from the 600g CQP titanium ones, which are briliant but completely unavailable) is the TA Alize, which would build to about 760g complete with TA Axix Ti BB and 48t 3/32" ring, which is no lighter than your Dura Ace if you got a Phil Wood 108mm JIS Ti BB.

TA Vega light with a single ring looks like it could be light, especially if you had a custom spiderless chainring made to fit on the spider mounting splines.


The TA Alize Pista seems to be my best best. It matches up with the 103mm TA Axix Pro Ti BB, right? And it's 130bcd? That will be nice since I can run it with a tiny Hegoa chainring.

Edit: Argh, it looks like the TA crankset yields a 45mm chainline.

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mitre_tester
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by mitre_tester

Image
Last edited by mitre_tester on Sun Jul 18, 2010 11:59 pm, edited 1 time in total.

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ras11
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by ras11

Mile Ditch wrote:
Irish wrote:I've used Record Carbon road cranks with Miche chainrings mounted on out side on my track bike with no problems(chainline 42.5 afaik).
Ultratorque or the older square taper ones?


Can't be Ultratorque... the BB wouldn't fit.
:-) Toys-R-Us

waychel
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by waychel

mitre_tester wrote:
waychel wrote:
mitre_tester wrote:Lightest in my stable (apart from the 600g CQP titanium ones, which are briliant but completely unavailable) is the TA Alize, which would build to about 760g complete with TA Axix Ti BB and 48t 3/32" ring, which is no lighter than your Dura Ace if you got a Phil Wood 108mm JIS Ti BB.


The TA Alize Pista seems to be my best best. It matches up with the 103mm TA Axix Pro Ti BB, right? And it's 130bcd? That will be nice since I can run it with a tiny Hegoa chainring.


I think your best bet would be to keep the Dura Ace crank and buy a Phil Wood Ti BB; the TA cranks are no lighter than the Shimano square taper ones.


Thanks! I managed to track down a 42t, 144bcd Salsa ring, so I hope it works with the Dura-Ace spider.

Irish
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by Irish

Square taper, but don't see any reason why UT wouldn't work, same chainline(42.5) and same Q factor. You would have to do a job on the chainring bolts as the ut ones are different diameter(smaller) to standard bolts.

waychel
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by waychel

mitre_tester wrote:Lightest in my stable (apart from the 600g CQP titanium ones, which are briliant but completely unavailable) is the TA Alize, which would build to about 760g complete with TA Axix Ti BB and 48t 3/32" ring, which is no lighter than your Dura Ace if you got a Phil Wood 108mm JIS Ti BB.

TA Vega light with a single ring looks like it could be light, especially if you had a custom spiderless chainring made to fit on the spider mounting splines.


Hi, sorry to bother you again, but I heard that the square taper DA cranks are actually ISO, not JIS. Have you any insight into this?

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mitre_tester
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by mitre_tester

Image
Last edited by mitre_tester on Mon Jul 19, 2010 12:10 am, edited 1 time in total.

waychel
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by waychel

mitre_tester wrote:
waychel wrote:Hi, sorry to bother you again, but I heard that the square taper DA cranks are actually ISO, not JIS. Have you any insight into this?


Seems incredibly improbable. Since you actually have the cranks, just look at the back for the JIS logo.
Image


Unfortunately, that logo is nowhere to be found.

The only writing is:

SHIMANO FC-7600
VIA Japan NJS 165 MC

Is there any other way to tell? I know Shimano stuff is JIS, but on Sheldon's ISO vs. JIS page, he notes that older NJS cranks are ISO.

I believe Sugino 75s are ISO.

Any other way to tell?

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mitre_tester
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by mitre_tester

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Last edited by mitre_tester on Mon Jul 19, 2010 12:09 am, edited 1 time in total.

by Weenie


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11.4
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by 11.4

Neither bottom brackets nor crankarms typically have taper designations on them. That includes a JIS logo. You just have to know what you have.

Shimano itself says that the 7600 cranks are ISO. Sugino says the same thing about Grand Mighty and 75 crankarms. But ... and this is hilarious ... the Sugino technical documents say that their bottom brackets are all JIS taper. And Shimano has been quoted saying the same thing about their last square-taper bottom brackets.

This is all complicated by the fact that JIS and ISO measure taper dimensions differently. It's not just the angle but also the length and the actual starting width. And the measurements aren't maintained all that well either. We looked at a half dozen brand new 7600 crankarms and couldn't find much consistency among them, or even from left to right. The variance was greater than the variance between ISO and JIS. Lest anyone cast aspersions at Japanese millwork, we checked a pile of Campy Pista crankarms and found the same. The truth is, the tapers are pretty crude and stories of damaged caused by mismatch are very few and far between -- in the category of urban legend. I've seen Campy crankarms that were horrible matches to Campy bottom brackets, so I think it's about inaccurate machining more than about mismatching of two precision surfaces. Excessive or insufficient torquing on the crank bolt can also cause significant difference in fit (and in damage to crankarm or spindle).

So where does that leave us? I'd continue to recommend that you match brands in crankarm and bottom bracket. That way at least you have warranty coverage if you have a problem. Wish there was an accurate answer to your question, but the documentation itself is funky and the actual pieces are so inconsistently machined that you couldn't measure and know which one it was anyway.

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