Sturmey cog not working out ... good choices in compact cranks?
I built up my 29"er in October with 34x22 gearing, using a Sturmey-Archer (!) cog. Redhaze has been doing this for a while, and it turned out that after just a couple minutes of filing it slips right onto a Shimano freehub. I wasn't sure about the long-term durability of this setup, since the cog has only three splines - and since the cog's splines have rounded edges, whereas the freehub splines are square-edged. OTOH, the XT hub shell is steel so it should be reasonably durable. Thought I'd run this setup for a while and see how it held up.
Well, after 200 miles the Sturmey cog is starting to chew up the freehub body a bit. Not enough to cause substantial damage, but enough to cause concern about the long-term viability of this setup. My main options are either (a) stay 34x22 and buy a Boone Ti cog, or (b) drop down to a 32x20 setup. The latter option means new cranks, since my 12 year old DXs are 110/74, but I've been considering replacing those relics anyway. Going to stay with square taper.
Some of the crank choices appear to be:
- NOS Ritchey 94/58 5-arm cranks. Cambria's got these for $60 (arms only), and they frequently come up on eBay for about the same price. I've heard really good things about the stiffness of Ritchey's unique 5-arm design.
- Ritchey Comp 4-arm cranks. Cambria's got the square taper version of these for $60 too.
- Shimano LX M570. Hollowtech arms but still square taper, ALSO $60 at Cambria.
I don't have a strong preference in the 5-arm vs. 4-arm department as long as they're good cranks. My criteria are durability, stiffness (since it is a singlespeed) and reasonably light weight, in that order. (And of course price - I'd like to stay under $100, 32t ring included)
Experience or opinions on any of these?
Ok, here goes....
--The 5-arm cranks are better for singlespeeding than the 4-arm ones; chainrings for the former are better supported and less likely to warp under load.
Originally Posted by GlowBoy
--The Ritcheys score more style points, since they're relatively rare and non-Shimano. However, the "hidden 5th arm" design is a bit of a pain to work with, since you have to have an extra-short chainring bolt, and tighten it down in a very confined space. The best way to go here is to get a TA self-inserting (serrated) bolt; Sheldon Brown or Peter White could give you the hook-up.
Hope this helps.
You can also use a <a href="http://www.spicercycles.com/index.cgi?cat=18&sub_cat=Cogs&prod_id=334&cat_desc =Mountain">GCA</a> from Spicer and a 22t granny chainring.
Originally Posted by GlowBoy
Thanks, that's just the kind of info I was looking for
Hey, thanks for the feedback. That's just exactly what I wanted to know. I'll stick with 5-arm. Fortunately I don't change rings on my mountain bike very often (the other bike is a very different story) so I won't worry about the 5th-bolt difficulties. Appreciate the information.
Originally Posted by >>ECB<<
Also thanks itsdoable for the GCA tip.
30 tooth rings are available in a 74mm 5 bolt pattern (tandem inner rings), you'd be able to keep your cranks, all the cranks that you had mentioned are fine, but are designed to work with a narrow spindle (107mm~113mm) whereas your dx cranks would use a longer spindle...Can you source out a 22 tooth "uniglide cog" these are the pre hyperglide cogs with a taller "twist" tooth profile...Works good for singlespeed use..
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