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The perfect CX/road...
 

[Closed] The perfect CX/road gearing

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[#6751511]

Just wondering whether anybody has struck upon the perfect gearing for CX and road riding.

FWIW I run 46/36 front (CX70 cranks) with a 12/30 cassette and Ultegra (6700?) mech. It's great for 95% of my riding. I went under 3hr 30 at the 3Peaks (just!) but I could have done with a bail out gear on the final climb. At the other extreme I foresee spinning out at the Paris-Roubaix sportive this year.

Would an 11/32 XT cassette work? Or has anybody found a good range by swapping their chainrings?

I would very much like to have my cake and eat it. Thanks.


 
Posted : 05/01/2015 7:19 pm
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Triple.


 
Posted : 05/01/2015 7:25 pm
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A triple? It certainly covers the widest range though you do lose some kudos and some clearance.


 
Posted : 05/01/2015 7:27 pm
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Crickey, no triple! But thanks.

Anybody know if a 10sp XT casette (11/32) works with Ultegra shifters and rear mech?


 
Posted : 05/01/2015 7:31 pm
 aP
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Paris Roubaix sportive is next year.
Just change the cassette - wide one for cx and straight through block for road.


 
Posted : 05/01/2015 7:32 pm
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Daiboy, why not a triple? It provides you with exactly what you have asked for.


 
Posted : 05/01/2015 7:36 pm
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I guess I'm just looking to tweak what I've got rather than buy a new set of cranks/shifters. Plus there's the whole snobbery thing which is to be obeyed!


 
Posted : 05/01/2015 7:43 pm
 P20
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You can get an Ultegra rear mech that will work 11-32 11spd cassette. Wor lass has one on her Rose cyclocross


 
Posted : 05/01/2015 7:47 pm
 cp
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No such thing, all a compromise.


 
Posted : 05/01/2015 8:00 pm
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The 11-32 or 11-34 XT cassette will work if you fit a 9 speed Shimano MTB rear mech.


 
Posted : 05/01/2015 8:09 pm
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32t will be fine with a short cage rear road mech. I'm running one on one of my 'cross bikes.


 
Posted : 05/01/2015 8:17 pm
 womp
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Watching with interest, so max is 32T with Ultegra mech

I'm thinking of going the whole hog and putting a 11-40 with an XT mech


 
Posted : 05/01/2015 8:27 pm
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I presume you're on 10 speed if you think it's 6700?

SS Ultegra mech may work with 30+ depending on the hanger.

GS mech will work with 32.

Sram 1050 and 1070 cassette comes in 11-32 and 12-32

Great time on 3P. 🙂


 
Posted : 05/01/2015 9:37 pm
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Plenty of options for lower gearing above but is the difference between 46:12 & 46:11 enough top end?

46:12 is around 50 kmh @ 100 cadence, that should be fast enough?


 
Posted : 05/01/2015 10:10 pm
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Can you not get a slightly smaller front chainring on? My setup is 44:34 with 28 on the back. It is fine for 96% of my riding. Wit ha 34:30 gear you might be fine. You'll find that everyone wants a bail out gear but given you did ok you obviously didn't need it.

I doubt you'll spin out with 46:12. Granted you won't be able to hammer the descents but they are not Alpine. In that gear at 90rpm cadence you'd be going 27mph. Comfy for a group.

http://www.machars.net/bikecalc.htm


 
Posted : 05/01/2015 10:28 pm
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Thanks for all the comments. The variety of responses is exactly why I'm asking - I've heard lots of contradictory advice over whether or not the XT cassettes work with 10sp Ultegra mechs. Some say you need mtb mechs...

I figured it may be a compromise but without delving in to gear inches and all the formulae I hoped, considering the many gear combinations that are possible, there might be an ideal middle ground between CX and roadie gearing. Maybe that one extra gear with 11sp is the secret!


 
Posted : 05/01/2015 11:01 pm
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Awesome, just seen the link, thanks jonba


 
Posted : 05/01/2015 11:23 pm
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i've got an 11-34 cassette on my kaffenback with a 105 medium cage mech (10 spped) there's plenty of space left - i think it would take a 36!

shifting is fine, although obviously the jumps are large but theres no way round that with a big top end


 
Posted : 05/01/2015 11:26 pm
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If you can find a cassette to try then you can just try winding in the b screw as much as possible. I've seen bodges with a substitute longer screw used or simply taking it out an putting it in the other way so the head gives the extra depth to push the mech out.

The gospel according to Sheldon Brown

http://sheldonbrown.com/deakins/lowgears.html


 
Posted : 05/01/2015 11:44 pm
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I would've said 36/30 was a bailout gear for penygent, at 3:30 I don't think it slowed you up much. But for road riding you want bigger rings on the chainset. I'd swop the 46 out for a 50 or 52.


 
Posted : 05/01/2015 11:47 pm
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You can get an 11 speed Ultegra 11-32 cassette (not sure about the 10 speed), I know, I ordered one this morning and a Medium Ultegra rear mech to go with it.
My bike currently has Sram Apex 46/36 front and 11/32 10spd rear, it does me most of the time.


 
Posted : 05/01/2015 11:56 pm