Triple to Double query

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stevenb
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Triple to Double query

Postby stevenb » Mon Dec 03, 2012 14:53 pm

My bike has a 10 spd triple shiomano set up.
I want to go to a double and am happy to buy a XT chainset and double front mech and then sell my existing bits.
If I do this is there anything else I need to do with either the front cog shifter unit and chain length?

I have searched on the forum and found part answers but not specific to my enquiry.

Many thanks.

nferrar
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Re: Triple to Double query

Postby nferrar » Mon Dec 03, 2012 14:58 pm

You shouldn't need to change the chainset or mech (unless 10-speed is different from 9-speed in that regard, can't see why though). You might need a different 'middle' ring depending on what you have now to give you something between your current middle and old big ring and then stick a bash guard on instead of the big ring. Front mech will be fine, you just need to set it's limit screws, there are double-specific mechs (I have one) but that's just for a slightly better change (supposedly) as you have a bigger jump between the chainrings. Your chain you should shorten (assuming your biggest ring on the front will be getting smaller), shifters don't need changing.

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nicklouse
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Re: Triple to Double query

Postby nicklouse » Mon Dec 03, 2012 15:01 pm

just buy and fit rings the size you want and set the mech to stop over shifts.

chain will need to be shortend-lengthened-or left alone depending on what you do. chain sizeing is around the two biggest cogs without the rear mech and add 1" (one full link if shimano) see parktools.
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njee20
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Re: Triple to Double query

Postby njee20 » Mon Dec 03, 2012 15:04 pm

You shouldn't need to change the chainset or mech (unless 10-speed is different from 9-speed in that regard, can't see why though). You might need a different 'middle' ring depending on what you have now to give you something between your current middle and old big ring and then stick a bash guard on instead of the big ring. Front mech will be fine, you just need to set it's limit screws, there are double-specific mechs (I have one) but that's just for a slightly better change (supposedly) as you have a bigger jump between the chainrings. Your chain you should shorten (assuming your biggest ring on the front will be getting smaller), shifters don't need changing.


We've done this - changing to a 'proper' double, rather than just changing rings.

So yes if you change your front mech and chainset you shouldn't need any other parts. If you front mech is smaller you can shorten your chain (not absolutely essential though), and you should have a small screw on your LH shifter to select between '2x' and '3x', which you'll need to change - the spacing on the doubles is slightly different.

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stevenb
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Re: Triple to Double query

Postby stevenb » Mon Dec 03, 2012 15:14 pm

njee20 wrote:
You shouldn't need to change the chainset or mech (unless 10-speed is different from 9-speed in that regard, can't see why though). You might need a different 'middle' ring depending on what you have now to give you something between your current middle and old big ring and then stick a bash guard on instead of the big ring. Front mech will be fine, you just need to set it's limit screws, there are double-specific mechs (I have one) but that's just for a slightly better change (supposedly) as you have a bigger jump between the chainrings. Your chain you should shorten (assuming your biggest ring on the front will be getting smaller), shifters don't need changing.


We've done this - changing to a 'proper' double, rather than just changing rings.

So yes if you change your front mech and chainset you shouldn't need any other parts. If you front mech is smaller you can shorten your chain (not absolutely essential though), and you should have a small screw on your LH shifter to select between '2x' and '3x', which you'll need to change - the spacing on the doubles is slightly different.


Cheers for the help everyone.
I want to get the chain line right for sweet shifting you see. I don't like bash guards so would prefer a double specific chainset. I always use my gears efficiently with no big/small, small/big, ring combo's used.

I currently run a 24/32/42 chainset so a 38/26T combo would do me perfectly. I have a XT long arm rear mech already.
I think I read that the double specific front mech allows better adjustment to the cage when setting up with a double chainset too.
Do you know the location of this screw on the shifter?
Cheers again

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cooldad
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Re: Triple to Double query

Postby cooldad » Mon Dec 03, 2012 15:23 pm

Ignore this
I don't do smileys.

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stevenb
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Re: Triple to Double query

Postby stevenb » Mon Dec 03, 2012 15:59 pm

cooldad wrote:Ignore this


You mean Ignore as in not to convert from triple to Double or ignore your actual post?

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The Rookie
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Re: Triple to Double query

Postby The Rookie » Mon Dec 03, 2012 16:10 pm

You don't need a double specific to get the chainline right,. just use 2 adjacent chain positions (mid granny or big middle depending on chainring sizes) and ad/remove spacers to get the chainline right.

Also depends what rings you run, many on a double opt for something like 26/36 for a trail bike, if you do that you'll do 80% of riding on the big ring and only use the granny for climbing on the big gears at the back, if so the standard middle and granny locations work perfectly, better than if you adjust the chainline (which doesn't affect shifting over much anyway).

To summarise, what is 'best' depends on what you intend to do it it, not just that it's now a double

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cooldad
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Re: Triple to Double query

Postby cooldad » Mon Dec 03, 2012 16:31 pm

stevenb wrote:
cooldad wrote:Ignore this


You mean Ignore as in not to convert from triple to Double or ignore your actual post?

Ignore my actual post as I typed more garbage than usual.
I don't do smileys.

There is no secret ingredient - Kung Fu Panda

London Calling on Facebook

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njee20
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Re: Triple to Double query

Postby njee20 » Mon Dec 03, 2012 19:39 pm

many on a double opt for something like 26/36 for a trail bike


That would be daft, 24/36 would be better, or 26/38, as the OP wants.

But yes, no specific advantage getting a 'proper' double, just looks a bit neater. The ring positions are in between the 3 of a triple, and on XTR the q-factor (distance between cranks) is smaller. I run 2 rings on a triple chainset for years before running proper doubles and it makes no real difference in use IMO.

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stevenb
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Re: Triple to Double query

Postby stevenb » Mon Dec 03, 2012 22:01 pm

njee20 wrote:
many on a double opt for something like 26/36 for a trail bike


That would be daft, 24/36 would be better, or 26/38, as the OP wants.

But yes, no specific advantage getting a 'proper' double, just looks a bit neater. The ring positions are in between the 3 of a triple, and on XTR the q-factor (distance between cranks) is smaller. I run 2 rings on a triple chainset for years before running proper doubles and it makes no real difference in use IMO.


Thanks everyone for sharing your knowledge.
I didnt doubt your knowledge for a single moment but as I'm a bit of a perfectionist I have just bought Shimano XT double 38/26T chain set, XT double front mech and XT 11-36 cassette all in new for an excellent price. I got the cassette because I just fancied a little extra.


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