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I'm building up a fast 29er hardtail. Whatever you think of the merits of that decision, I'm after some help on the chainset.
Need (want...):
- Lightweight
- Stiff
- Double rings, 38/26
- Lower Q factor than XT triple - I've always found my pedal stance a bit wide. Feels unnatural.
- Don't particularly want carbon
- BB92 compatible
On insurance so cost less of an issue than it would normally be, which is a good situation. Although no need to go stupid expensive.
So far: XT double has same Q factor as the triple. Only the XTR Trail (vs. Race) offers the right chainring combo for the bigger wheels, but has the wider Q factor; the Race has narrower Q factor but the rings are sized for 26 wheels. Rotor - can't really find out where to get one in the UK. Race Face - stupid expensive and struggling to find a chainset with small enough rings.
SRAM XX? But wouldn't this only work with Truvativ / SRAM BB, not BB92?
Anyone got any bright ideas?
Middleburn X-Type
Good shout Michael. Thanks. Only problem - the Middleburn has a Q factor of 172mm. I.e. not very narrow at all. Running out of ideas...
rotor: [url= http://www.velotechservices.co.uk/shop/Vprod4.asp?cat=7404004818 ]http://www.velotechservices.co.uk/shop/Vprod4.asp?cat=7404004818[/url]
And thank you as well - had looked at Rotor too, but BB30 axle on the Rotors incompatible with BB92 frame...
What frame? Is this BB92 like Trek carbon frames; bearings pressed directly into the frame, or like On-One, Lappiere etc; bearings housed in a press-fit unit.
You can certainly get SRAM compatible bearings for the former, you could presumably use the Hope adapters on the latter.
XX is heavier than XTR though, and more expensive.
What about XTR Race with 28/40, will it make that much difference? Still gives you a decent low gear with the 11-36 block.
Thanks for your thoughts.
Scott Scale 29er. BB press fits into the frame? (I think - although bike shop where I have to go to get the insurance replacement have been fairly hopeless at responding to queries). Using one of these: http://www.chainreactioncycles.com/Models.aspx?ModelID=44225
My understanding (although I might be wrong) is that the Hope adapter only works with a Hope BB, and wouldn't work with the above Shimano BB.
Have been wondering about XTR Race, although bit concerned about 28/36 on a 29er when riding up big mountains. Even the top end fully built Scale 29 (i.e. for fast people) comes with a 26 inner ring.
Looking at the full bike again on the Scott website, it seems you can get GXP press fit bearings to fit the frame - I didn't realise you could.
But then there's the issue as you say of XX being heavier and more expensive than XTR! I've heard various comments of cheese-like chainrings too...
Flipping minefield.
It's PF30 then, which is different again, as you can use BB30 cranks. In that instance I'd get XX, definitely.
Top end production bikes are designed for rich people, not fast ones! Plenty of people running single ring out there, a 26/39 bottom gear is pretty low, even on a 29er.
Hmmm. Fair point re rich people / fast people! It seems that for example Burry Stander rides a 42/28, and no doubt other pros similar, although I guess they might change to suit short XC (where he was using that set-up) vs. long stage races / marathons (which is what I'll be doing). But then he is also ridiculously quick, and I'm not.
Just made use of good old Sheldon's gear calculator. 39x11 on 29 comes out at 103".
42x11 on 26 is 99", 44x11 is 104". Both of which I've raced on quite happily.
Think that means I ought to be fine on the 39. And I reckon the 26 is worth having vs. the 28. 26x36 on 29 is 21", vs. a current granny gear of 22x32 on 26 of 18". Guess I'd better just HTFU. 28x36 on 29 is a potentially uncomfortable 23" though.
I think it's looking as if the XX option wins the day.
Do you really use 22/32 though? If you do, a double isn't really for you!
If you're worried about that bottom end just get a Shimano triple.
road triple?you can go down to 24 on the inner.38 middle.bash.chainline might be a bit off.