front mech help

bulliporker · Oct 5, 2013

recently got back into mountain biking and bought myself a 1999 orange gringo for very little money , just noticed on the front shimano mech part no fdmc 18 , unless i am running on the small front chainring i have alot of play in the front mech what seems to rattle, it still changes gear perfectly ok but something is amiss is it a simple fix or am i better of to replace , its running a 8 speed rear cassette and its a top pull front mech , other than that how do i know what size it is, as i have no way of measuring seat tube and can i fit a new 9 or 10 speed xt front mech to my 8 speed gear system

legrandefromage · Oct 6, 2013

The front mech doesnt care what speeds you are running. The basic design hasn't changed much since about 1994 so just about anything will fit. However, cable pull can vary between shifter. It helps to match the front shifter model with the mech. With the current range it does seem to matter as much, Deore seems to fit and work with everything.

To find out the size, check on the inside band of the mech, it wiil be 28.6mm, 31.6mm or 34.9mm. Most new mechs come with shims to suit.

NeilM · Oct 6, 2013

Is it the mech that is rattling, or is it the chain rubbing on the mech?

If it's the chain, then a few minutes adjusting the cable pull to get a little extra clearance will do the trick.

drystonepaul · Oct 6, 2013

The MC-18 front mech is an Alivio low band or top swing version. ie the linkages are above the clamping band. These are notorious for developing play over time as the pivots wear.
In my experience this is true for all mechs of this type.

They all rattle regardless of the cable tension. In the inner chainring position the mech will be resting on the limit screw which will minimise rattle.

Ultimately though, while the existing mech will still work, a new mech is the only way to cure the rattle.

front mech help

bulliporker

Retro Guru

legrandefromage

NeilM

drystonepaul

Similar threads

Latest posts