Replacement Front Mech

[Tom B]

Hi Guys

I currently have a Shimano FD-M311 that is broken.

I have never been over taken with it and getting it fix or clamp firmly to the seat tube has always been problematic and it has rotated on a number of occasions.

The bike is fitted with a triple and largest cog is a 48t ring and a 8spd cassette.

Can someone recommend me a sensible priced replacement upgrade - FD-311s can be found for a bout £15?

 

[Ajax Bay]

What is the diameter of your seat tube?

 

[DaveReading]

I have never been over taken with it

That's a h*ll of a recommendation, where can I get one of those ?

Joking aside, I'll be equally interested to see what other CC'ers recommend. I've got an FD-2303 (31.8 mm seat tube) and lately I've been having trouble adjusting it to eliminate chain rub on one side or the other.

 

[Ajax Bay]

I've got an FD-2303 (31.8 mm down tube) and lately I've been having trouble adjusting it to eliminate chain rub on one side or the other.

Off topic. I'm using a 5503. Once you get it right, there should be two positions (separated by a click) for the small chainring, and then, probably, two for the middle. It is difficult to avoid rubbing if you go large to largish, or small to smallish (but you would be advised to avoid that anyway - just use the 'rubbing' noise as a prompt to change chainrings. You may also find that when on the middle chainring you can't use (without rubbing) the largest or smallest sprockets. Of course these gears are available to you by changing to the more appropriate chainring - again just use the 'rubbing' noise as a prompt.

 

[Tom B]

Hi again

Seat tube diameter is 31.8mm

 

[DaveReading]

Once you get it right, there should be two positions (separated by a click) for the small chainring, and then, probably, two for the middle.

Thanks. I think you're describing the "trim" facility that some shifters provide but not, alas, mine.

It is difficult to avoid rubbing if you go large to largish, or small to smallish (but you would be advised to avoid that anyway - just use the 'rubbing' noise as a prompt to change chainrings. You may also find that when on the middle chainring you can't use (without rubbing) the largest or smallest sprockets.

No, I try not to cross-chain, the rub occurs under the latter circumstances that you describe.

I'm overdue to change the FD cable after it got damaged when I came off recently, so I'll have a fettle. It's the fact that the relationship between the derailleur and chain works in two dimensions (well two-and-a-half if you include rotating the FD on the tube) that I'm still trying to get my head around.

 

[Ajax Bay]

Documentation for 2300 (here) @DaveReading on the Shimano website and it says:

"Trimming (noise prevention operation) < ST-2300 >
If the chain is on the large front chainwheel and the larger rear sprocket, the chain will rub in the front derailleur
plate, producing a characteristic noise. When this happens, press lever b lightly (to the point where it clicks); this causes the front derailleur to move slightly towards the smaller chainwheel, thereby eliminating the noise."

 

[Ajax Bay]

Seat tube diameter is 31.8mm

I'd just get another Altus FD (311) and shim it down to 31.8 (the shims may come with the FD). A 9sp FD would work almost as well and may be easier to procure. The only difference between 8sp and 9 sp FD is that the chain is very (very) slightly narrower, but this makes minimal difference to the dimensions and operation of the FD.

 

[DaveReading]

Documentation for 2300 (here) @DaveReading on the Shimano website and it says:

"Trimming (noise prevention operation) < ST-2300 >
If the chain is on the large front chainwheel and the larger rear sprocket, the chain will rub in the front derailleur
plate, producing a characteristic noise. When this happens, press lever b lightly (to the point where it clicks); this causes the front derailleur to move slightly towards the smaller chainwheel, thereby eliminating the noise."

Thanks, but according to the docs that only applies to the ST-2300 (double). The triple shifter (ST-2303) only trims when on the small ring (where I don't get any chain rub).