Fitting a K-Edge chain catcher to a carbon frame.

[Globalti]

I'm still getting chain drop about 1 in 5 changes no matter how I adjust the front derailleur or how carefully I change down to the small ring. I'd like to fit a chain catcher but because the frame flares out towards the BB I can't fit the Deda Dog Fang or any other similar clamp-on device so it's got to be a K-Edge, which bolts onto the frame mount bolt of the derailleur. See: http://www.wiggle.co.uk/p/cycle/7/K-Edge_Chain_Catcher/5360044389/

In order to do this I will need to ditch my band-on derailleur and buy a bolt-on derailleur along with a band and maybe also a hard-to-fit adaptor for the K-Edge. Has anybody done this and what parts did you use? How did it work in the end? This little exercise won't leave me much change from £100 so I want to get it right!

 

[dodgy]

Sorry I can't help, but I can't believe how much one of those things costs!

 

[Theseus]

RR, dumb question alert, but have you tried setting the limit screws on the front mech so that it doesn't move so far?

 

[Globalti]

Oh God yes, believe me!

Actually the only thing I haven't tried is shortening the chain a little. Might do that this evening.

 

[manalog]

How about the tension on the rear mech, perhaps the tension is on the low side. Try the chain lenght calculator before shortening it
http://www.machinehead-software.co.uk/bike/chain_length/chain_length_calculator.html

 

[02GF74]

it may be that the front derailleur is not compatible with your frame and chain set/bottom brtacket? have you replaced any of them recently?

it should be possible to set the limit screw so that the chain will not shift from middle to small ring - are you able to do that?

is you chain worn?

is this a new problem or always done it?

is the place where the front shifter is fitted on the seat tube correct? you may need to raise or lower it. what make/model/year front shifter is it?

if the inner ring is too far out then you will have a problem with setting the adjuster.

I came across a problem like this on another bike.

Is the adjuster screw bottoming out? Then try fitting a longer screw.

 

[NickM]

it may be that the front derailleur is not compatible with your frame and chain set/bottom brtacket? have you replaced any of them recently?

Specifically (if Shimano - I have no knowledge of other makes), the front mech should be from the same groupset as the crankset. For example, a 105 (5503) front mech is shaped to work with 52/42/30 rings, and expects a 10-tooth gap between large and middle rings. A Dura-Ace (7703) front mech expects 53/39/30 rings and a 14-tooth gap between large and middle rings.

I'm assuming that:

a) you haven't changed the rings for different sizes
you haven't altered the front chainline
c) I'm not teaching my granny to suck eggs!

Sorry I can't help, but I can't believe how much one of those things costs!

You're not kidding! But then, it is a "precision component"

 

[Globalti]

That's interesting. The front derailleur is 105 and the bike came with an FSA 50/36 but I currently have a 34 inner. I didn't ride it very far with the 36 so don't know if my small change has caused the problem.

What I am beginning to think is that it's a chain tension problem, the chain may be a little too long as even if I put it on big - big the jockey wheels are not straightened out anywhere near their limit. I have tightened the tension screw and adjusted the front derailleur limit screw so that the cage is only just moving over enough and no further. That the problem happens when I'm careless and not applying steady even pressure to the pedals as I change mght also indicate that the drop in size is so massive that the chain is just slopping off. I will try taking out a link and see if that helps.