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PostPosted: Sun Feb 17, 2013 11:15 pm 
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I'm putting slicks on one of my MTB projects with a 13-23 7 speed block. Ideally want to use a short cage rear derailleur and have an XT RD-M732 which is marked with max 28 total 28 which I understand is max cog at rear 28 and max capacity of difference in rear cogs (10 in this case) plus difference at front which is currently 24-36-46 ie 22 and hence total is 32 ie too much.

A bit of research says some of the Shimano figs are conservative, has anyone tried this sort of thing. Also I need to replace a couple of jockey wheels, and was wondering does having 10 or 11 toothed jockey wheels make much difference.

QUESTION RESOLVED - PICS FURTHER DOWN


Last edited by daugs on Wed Apr 24, 2013 9:45 pm, edited 2 times in total.

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PostPosted: Mon Feb 18, 2013 8:26 am 
retrobike rider
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get the same tooth cog as it was designed for. otherwise they'll probably not fit particularly well ;-)

Your setup will work fine.


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PostPosted: Mon Feb 18, 2013 8:35 am 
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thanks for that - good news, currently they are 10 tooth and assume thats right for the mech although most seem 11, if anyone can confirm that would be great, cheers


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PostPosted: Mon Feb 18, 2013 10:32 am 
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Shimano's figures are for what works guaranteed. Things that throw it out are: short chainstays, thick dropouts, fat seat tubes etc.

I reckon you will just about get away with it. Whatever you do, ensure it will work on the big-big combination (it might be a bit rattly) - small-small might have the chain tension a bit loose.

Worth a try I think.


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PostPosted: Mon Feb 18, 2013 6:11 pm 
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If you do the calculation again without the big sprocket and big chain-ring / small sprocket and small chain-ring combination chances are you will be fine :wink:


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PostPosted: Mon Feb 18, 2013 8:32 pm 
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The best case is that the chain goes slack on small-small, which is fine. Whatever you do, ensure you can engage big-big. If the chain is too short it tends to stuff the rear mech into the spokes, followed by a collapsed wheel and crash. :shock:


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PostPosted: Tue Feb 19, 2013 9:24 am 
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hamster wrote:
The best case is that the chain goes slack on small-small, which is fine. Whatever you do, ensure you can engage big-big. If the chain is too short it tends to stuff the rear mech into the spokes, followed by a collapsed wheel and crash. :shock:
:shock: yes will try to avoid that one

I've always checked the chain length on big-big plus 2 links (without gears) when fitting to get the right number of links rather than big-small with gear at vertical ish but is there a definitive way to check chain length ?


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PostPosted: Tue Feb 19, 2013 12:00 pm 
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Your method is exactly what Shimano recommend!


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PostPosted: Tue Feb 19, 2013 12:12 pm 
King of the Skip Monkeys
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Cant find a pic but I ran a Ging chain device with my 32/11t - 39/53t drop bar on-off road work bike.

Edit: could be a 30t but it was an XT/ 600 mixamech!

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PostPosted: Mon Apr 22, 2013 7:12 pm 
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finally got round to posting on this but all sorted and works ok with 13-23 on rear and 24-36-46 on front with XT mech as per OP, all runs pretty slick changes and no issues even in ratios that wouldn't use

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