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[Closed] More gear ratios stuff

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We are going (mainly) road touring on the tandem later this year. Normally we run 22 / 36 / bash chainrings. For road work I think a big ring might be handy. Will it work to have 22/36/48 or is that too much gap? Especially with an 11/ 34 casettee?

It seems a bit daft to end up with 22/36/44 chainrings maybe I should change the granny ring for a 26 as well.


 
Posted : 14/07/2010 10:15 am
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36/46 was std back in the day, if the front mech can cope then go for it, 26 might be more useful also.


 
Posted : 14/07/2010 10:37 am
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Most of the "touring" versions of MTB chainsets are just that- 36/48. You'll be fine.


 
Posted : 14/07/2010 10:39 am
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Most of the "touring" versions of MTB chainsets are just that- 36/48. You'll be fine.

most are 26-26-48 are they not?

is there a rear mech which has that capacity?


 
Posted : 14/07/2010 10:44 am
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thats my concern - will the front mech go from a 22 to a 48? will that bee too much slack for the mech to take up?


 
Posted : 14/07/2010 10:45 am
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That would be my concern too - you'll need a very old std front mech or one to fit the c'sets Luke is on about, even then 26T is a big spread for it.


 
Posted : 14/07/2010 10:47 am
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thats a capacity of 49.

shimano quote 45T as the biggest for rear derraillers.

although there are a few threads on mtbr about exceeding that. and modifying cages.....


 
Posted : 14/07/2010 10:50 am
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Hmmmmm

maybe I'd better put the 26 chainring on as well - we are heading for the low countries so not many hills - but we will have full on camping gear

Ta


 
Posted : 14/07/2010 10:53 am
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Do you really need a 48*11 top gear for tandem touring? Why not just pop on a 32 and 44 ring and use a normal mech, much easier to set up and probably work nicer

I went touring on my Jake with only a 46*13 top gear (on 700*25mm) but it was ok, how fast do you want to go when touring anyway.

I normally run 22/36 on my Inbred and when I take that to New Zealand next year for a road tour I am gonna try 29/42 coz I have a med mech on the back and dont want to buy another to run a triple (plus I have 29 and 42 chainrings in my spares)


 
Posted : 14/07/2010 11:06 am
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If you're already running a 22T inner, then you've probably got a compact front mech. For what you're planning, I think the capacity of the front mech (ie the maximum size of your outer chainring) will be more of an issue than the rear mech capacity - although you might need to look at chain length for the sake of your rear mech.

Have a look at this for more detail - http://www.ctc.org.uk/DesktopDefault.aspx?TabID=%204068


 
Posted : 14/07/2010 11:15 am
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Restless native - I have a 48and a 26 chainring but not a 44 or a 32 I was trying to get the right gearing without buying more stuff. 48/11 is good for flying down hills - but I realize that we are not going to get many of them in the low countries are we ๐Ÿ™‚

Birly - I think the bike came with a bigger granny ring originally - maybe 26 / 36 / 48. I seem to remember having to move the mech down to fit the 22.

so the consensus is either go 22/32/44 or 26/36/48 but that 22/36/48 is just going to cause problems

Ta


 
Posted : 14/07/2010 11:25 am
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Ah, yes, a 22T granny. No idea whether that'll work to be honest. If you've got all the bits there's no harm in fitting it and going for a test in the Pentlands?

If you want a 44T I'm going to be back in Embra this week and think I have one knocking about you can gave.


 
Posted : 14/07/2010 11:32 am
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"trying to get the right gearing without buying more stuff"

aha, that I can identify with ๐Ÿ™‚


 
Posted : 14/07/2010 11:35 am
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If the rear mech can handle a 45 tooth difference, then if you use a 48:34 big ring/cassette ratio, when you are in your 22 granny you will have a slack chain when you go smaller than the 15t sprocket.

You're never going to be in that ratio anyway, so no need to worry about it.

EDIT - and the if you don't move the mech down, it will only rub when you try to engage the smaller sprockets when in granny, thinking about the chain path.


 
Posted : 14/07/2010 11:50 am
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That makes sense big john.


 
Posted : 14/07/2010 11:52 am