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PostPosted: Tue Apr 02, 2013 5:57 pm 
West Midlands AEC
West Midlands AEC
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Joined: Wed May 14, 2008 11:06 pm
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Location: Stow on the Wold, Glos
Dont really know where to put this but with Road gearing knowledge required thought I would get a better response than in +98 mtb?

-I have a modern cross bike with 5700 105 compact gearing 34/50 28t cassette

-I would like to increase the gearing for a upcoming event to a mtb 32t cassette?

-Now I understand that this can be done with a modern 9 speed rear mtb mech?

Can someone confirm what I actually need, Dont really understand why 9 speed mech and not 10 is needed (sti cable pull is different?) does this mean I will have to have a 9 speed cassette too? (makes sense) Also do I need a 9 speed chain or 10 speed for chainset?

So do i need

9 speed mtb mech
9 speed mtb cassette
9 speed chain

Help !! :lol:

Thanks

daj


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PostPosted: Tue Apr 02, 2013 7:40 pm 
Retro Guru

Joined: Fri Oct 28, 2011 12:59 pm
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Location: Chez Vegas, Derbyshire
I would have thought you could get away with changing the rear mech for a long cage (GS) one looking at the spec here: http://www.chainreactioncycles.com/Mode ... elID=85966


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PostPosted: Tue Apr 02, 2013 8:04 pm 
PoTM Winner
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You need a long cage rear mech. Then you could use a SRAM apex cassette, the go up large.

That said you already have 34x28 that will get you up anything. Where are you going?


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PostPosted: Tue Apr 02, 2013 8:13 pm 
West Midlands AEC
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Location: Stow on the Wold, Glos
Montello wrote:
You need a long cage rear mech. Then you could use a SRAM apex cassette, the go up large.

That said you already have 34x28 that will get you up anything. Where are you going?


Doing Hell of the North Cotswolds , 100k with Loads of offroad climbing, Some steep enough be nice to have a easy option near the end :D

Bit annoying seeing the mtb people spinning away when your tired :lol:


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PostPosted: Tue Apr 02, 2013 8:25 pm 
Section Moderator & South West AEC
Section Moderator & South West AEC
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Location: new forest
i'm confused here, 5700 is 10 speed? so why are you looking at 9 speed stuff? also what is the current cassette ratio?

why not just put on a mtb 10 speed cassette? you'll then need a long rear mech, and i would have thought the long cage 105 should do it and then a new/longer chain



also, personally i run 34/45 with a 13-26 on my cross bike, can do most things on those gears but yeah the easier gears for the HONC makes sense.


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PostPosted: Tue Apr 02, 2013 8:36 pm 
West Midlands AEC
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Location: Stow on the Wold, Glos
I have done some reading up jon and for some reason you cant combine 10 speed road shifters and a 10 speed mtb mech :? But with a 9 speed mtb mech you can run 10 speed cassette mtb ? ha,ha yeah thats why I want someone to tell me exactly :lol: :lol:


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PostPosted: Tue Apr 02, 2013 8:40 pm 
Old School Hero
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Location: Cheltenham
Why not look at an SRAM wifli option? Compatible with 5700 and if I recall correctly gives a 32 option. Good enough for Contrador, then again...


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PostPosted: Tue Apr 02, 2013 8:46 pm 
Retro Guru

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Location: Chez Vegas, Derbyshire
Funny I thought modern Shimano MTB and road had the same cassette spacing and the only thing stopping you using a bigger cassette was the mech cage size.

You learn something new every day about Japan's favourite fishing tackle maker.


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PostPosted: Tue Apr 02, 2013 8:49 pm 
Section Moderator & South West AEC
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Location: new forest
do you run 10 speed on any of your mtb's? if so swap the bits and see what happens, i would have thought that the cable pull and parallelogram is still the same for the amount of spacing so it should work, i haven't personally heard any different.

what i have noticed is that with a road mech (regardless of length of cage) running an mtb cassette the issue is the shorter reach 'knuckle' on the road mech which means that the cage itself can hit the sprockets of a wider ratio as you shift up.


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PostPosted: Wed Apr 03, 2013 3:20 pm 
Old School Grand Master
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Location: Lost in Translation
daj wrote:
I have done some reading up jon and for some reason you cant combine 10 speed road shifters and a 10 speed mtb mech :? But with a 9 speed mtb mech you can run 10 speed cassette mtb ? ha,ha yeah thats why I want someone to tell me exactly :lol: :lol:

You've got it right.

For 10-speed MTB (but not for road) Shimano changed the cable pull ratio and mech geometry, while using the same cassette spacing for 10-speed road and off-road cassettes. That means you can't index a 10-speed cassette with road shifters and an mtb mech.

You need a 9-speed MTB rear mech, a 10-speed MTB cassette, and a 10-speed chain.


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