Front mech advice

bigmul

Hi all,

I have a couple of bikes that need some help with changing gears up front. Both are Boardman's - first is a 2013 Road Race with Sora, next is a 2014 CX Team with Apex.

The CX I think I'll just get a 5600 105 for as a replacement for the dire microshift abomination.

The Road Race is what I'm unsure on. It has a Sora front mech at the moment with Sora STI. It will either rub in the lowest or the highest, never seem to be able to get it setup in the sweet spot. I can set it up so no rubbing in the big sprockets on the big ring, but then I'll rub on the outside of the cage lover down the cassette. I can push the STI lever more and the mech will move out but then come back in again without me pressing the other lever. Do I just need to replace the mech maybe?

Thanks!

ride_whenever

It is incredibly unlikely that you need to replace a mech with sora, rubbing in extremes isn't necessarily avoidable. Are you using the trim position on the shifter?

bigmul

Yep, on the big ring I have it set so there's no rubbing at the top of the cassette, then trim as I go down, but when I get to the bottom it rubs on the outside of the mech cage. I can push the shifter more and the mech will move more (outwards) but then comes back to previous position when I let go of shifter lever.

chrisvanderkaap

the problem is with the indexing (L stop) and the cable tension.
maybe the angle of the derailleur as well.

imposter2.0

bigmul wrote:

The CX I think I'll just get a 5600 105 for as a replacement for the dire microshift abomination.

Nothing actually wrong with Microshift stuff - it is functionally identical to any other front mech and the shift is perfectly reasonable. Front mechs are so simple that if you are having transmission problems, the issue is almost certainly not with the mech itself, unless it is physically damaged...

bigmul

chrisvanderkaap wrote:

the problem is with the indexing (L stop) and the cable tension.
maybe the angle of the derailleur as well.

If I can push the mech further out but it comes back again not sure how it could be the indexing stop? Surely that would mean it would move any further?

mattrixdesign2

Cable tension? Not enough? The only advantages I have seen on 'better' mechs is the adjustment screw settings tend to be a bit more precise and allow you to tweak things. No matter how you look at it the front mech is a crude and tough chain shifting device, they rarely go wrong and last forever.

chrisvanderkaap

bigmul wrote:

chrisvanderkaap wrote:

the problem is with the indexing (L stop) and the cable tension.
maybe the angle of the derailleur as well.

If I can push the mech further out but it comes back again not sure how it could be the indexing stop? Surely that would mean it would move any further?

i thought you could screw the "L" stop (on the smaller chainring!) in a little and decrease the cable tension so the distance (excess cable pull) between the two will be less and you should be able to shift more smoothly.

The alignment of the derailleur or the height on which it is set, also play a crucial role in actually making the shift, since the ramps on the mech need to be in the right place. Check that, but it is likely to be the first problem.

as you indicated the H stop should be allright since the mech physically wants to move over the big ring.

good luck chap!

rafletcher

I'd advise you download the Shimano tech docs and set it up as directed therein. You will most likely get chain-rub in big/big and small/small combinations with a CORRECTLY set up front mech. even with trimming. If you want no rub, then go SRAM with their yaw control from mechs. Or do what we all used to do (exept in race situations), avoid the bib/big and small/small combination.

bigmul

I do really like my SRAM setup with WiFli as barely ever take it out of the big ring!