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Permalink Reply by Ed Sneddon on November 10, 2011 at 10:20

if there's a science, then it's passed me by. I find it's a case of finding the midpoint/compromise where a) the cage isn't too stretched when running largest-to-largest and b) the chain is at least a cm from the upper jockey wheel when running smallest-to-smallest. I agree that shorter is probably better for changing, but it obviously need to be able to cross to the extremes just in case for when you lunge for that extra gear without a thought for crossing the chain.

I do notice that the longer chainstays on cx bikes makes it more forgiving than road bikes though. I recall having to adjust chain lengths on the road bike in the past for 11-23 to 12-25 (not sure why I ever thought I needed an 11...). However, on my cx bike I was surprised when I changed my cassette from 12-25 to 13-29 for the 3 Peaks that I didn't need to change the chain length (I probably should have, but I didn't have to), and that was on a short cage too.

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Permalink Reply by Lee Shunburne on November 10, 2011 at 10:52

Method 2 but adding two links. That's worked for me on all bikes since I first read it in MBUK about twenty years ago!

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Permalink Reply by Kristian Spreckley on November 10, 2011 at 11:38

I usually use the largest largest plus two links method on road but when building the cross bike I used Shimano's suggested method of large chainring, small sprocket and getting the cage at 90 degs to the sprocket and ground. Seems to work fine and shiting is good. I get quite a lot of chain slap on the chain stay especially in the small ring but I do run a 34 currently! Had thought about shortening fo rthis reason but it all seems to work quite well as it is.

Withthe exception that I often can't shift to the big ring after the first lap of a race. I can fettle it before hand and for the first lap it i sfine but then I lose shifting to the big ring. Seems tike the mud is causing issues. If I let the cage go further over, I then get it throwing the chain over the crank! Annoying having to ride round on the 34 for the rest of the race!

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Permalink Reply by Dave Haygarth on November 10, 2011 at 12:50

Thanks guys.  For the record I've generally used big ring and SECOND biggest sprocket plus TWO links but it's good to see what you do.  Might try and tighten up a touch and see.

 

Kristian: Silly thought and you've probably (possibly) got your front mech too high above the chainring if it over-throws or under-throws the chain.  Worth looking at?

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Permalink Reply by Michael Guilford on November 10, 2011 at 17:10

It depends on which bike its on. XC bike its a big priority to get it as tight as possible, road bike I tend to just chuck it on and make sure its not way too loose or way too tight in extreme gears. Cross bike is a single chain ring so i am constrained by the spread of the cassette i am using.

 

I tend to stick it in lowest front highest back and check that the chain will not be too loose (so rear cage facing back no more than 45 degrees from vertical), fit the chain then check that in the most extreme stretch gear i will be using (e.g big ring on front 3rd from lowest on rear) and check that i have the optimum stretch, and take a link out if it looks like it wont overstrecth the mech.

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Permalink Reply by Carl Nelson on November 11, 2011 at 1:21

Ditto!

Method 2 but adding two links. That's worked for me on all bikes since I first read it in MBUK about twenty years ago!

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Permalink Reply by Kristian Spreckley on November 11, 2011 at 10:23

Dave, deffo not. The mech nearly touches the chain stay and is well within the 1-3m limit set by Shimano. I'm going to make sure it works before I start on Saturday at Otterspool!Cheers

Dave Haygarth said:

 

 

Kristian: Silly thought and you've probably (possibly) got your front mech too high above the chainring if it over-throws or under-throws the chain.  Worth looking at?

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