Shimano Deore DX (FD-M650) and recommended chainline

[[email protected]]

Hello,
I recently bought on ebay a NOS Shimano FD-m650 Deore DX front
derailer (early '90s).
My current chainline is approximately 45mm or less and I find that
shifting from granny to middle ring requires too much force. This is
probably due to the fact that the chainring is too close to the
derailer and the leverage is not quite right (the derailer arm is too
vertical). Shifting from middle to large ring is much better.
What is the recommended chainline for such a FD? I am using a 135mm
MTB hub in the rear.

Thanks,
Federico

 

[Qui si parla Campagnolo]

On Jun 12, 4:56 am, "[email protected]" <[email protected]> wrote:
> Hello,
> I recently bought on ebay a NOS Shimano FD-m650 Deore DX front
> derailer (early '90s).
> My current chainline is approximately 45mm or less and I find that
> shifting from granny to middle ring requires too much force. This is
> probably due to the fact that the chainring is too close to the
> derailer and the leverage is not quite right (the derailer arm is too
> vertical). Shifting from middle to large ring is much better.
> What is the recommended chainline for such a FD? I am using a 135mm
> MTB hub in the rear.
>
> Thanks,
> Federico

Which shifters? DX FDers were often intended for top mount shifters,
coupled with strong spring FDers.

 

[[email protected]]

On 12 Giu, 14:30, Qui si parla Campagnolo <[email protected]> wrote:
> > My current chainline is approximately 45mm or less and I find that
> > shifting from granny to middle ring requires too much force. This is
> > probably due to the fact that the chainring is too close to the
> > derailer and the leverage is not quite right (the derailer arm is too
> > vertical). Shifting from middle to large ring is much better.
> Which shifters? DX FDers were often intended for top mount shifters,
> coupled with strong spring FDers.

The shifters are not the problem: I am using Campagnolo brifters.
What worries me is the high leverage itself:
1. the force required to shift is quite high, so the whole assembly
(FD, cable) looks stressed
2. a single click in the brifter causes a big movement in the FD (very
high leverage!) so I can't trim: usually Campy brifters require 3-4
clicks to shift, but in my case I shift from granny to middle with
just 1-2 clicks.

What I meant to say is that, exactly as for cantilever brakes where
the leverage has a significant effect on the brake "feeling", FDs are
affected by leverage more or less in the same way, and one can alter
the FD leverage by playing with the chainline.

Bye,
Federico

 

[A Muzi]

>>> My current chainline is approximately 45mm or less and I find that
>>> shifting from granny to middle ring requires too much force. This is
>>> probably due to the fact that the chainring is too close to the
>>> derailer and the leverage is not quite right (the derailer arm is too
>>> vertical). Shifting from middle to large ring is much better.

> Qui si parla Campagnolo <[email protected]> wrote:
>> Which shifters? DX FDers were often intended for top mount shifters,
>> coupled with strong spring FDers.

[email protected] wrote:
> The shifters are not the problem: I am using Campagnolo brifters.
> What worries me is the high leverage itself:
> 1. the force required to shift is quite high, so the whole assembly
> (FD, cable) looks stressed
> 2. a single click in the brifter causes a big movement in the FD (very
> high leverage!) so I can't trim: usually Campy brifters require 3-4
> clicks to shift, but in my case I shift from granny to middle with
> just 1-2 clicks.
> What I meant to say is that, exactly as for cantilever brakes where
> the leverage has a significant effect on the brake "feeling", FDs are
> affected by leverage more or less in the same way, and one can alter
> the FD leverage by playing with the chainline.

Is your gear wire on the top side of the anchor bolt? Mounting it on the
bottom side makes a huge difference in leverage, something like 22:20
(top) versus 17:20 (bottom).

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
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