front mech cable pull / shift ratio

[foz]

Does anyone have info on front shifter and mech cable pull / shift ratio? There's loads of info for rear mechs, but I can't find anything for the front. I know that shimano 8 speed STI won't move a 7 speed front mech far enough, not sure about anything more than 8 speed.

I've combined a 1050 6 speed friction DT lever with a shimano road 9 speed front mech - it works, but the lever only needs to move about half of the normal amount to change chainrings. Not really a problem, but would an 8 speed front mech require more gear lever movement?

Anyone got any numbers for front cable pull and shift ratio? I know the later 9/10/11 speed combinations wont work, and shimano made MTB and road different, I'm looking for info on 6/7/8/9 speed front mechs and shifters

thanks!

 

[stringfellow1946]

As far as I remember when Shimano went over to STI levers the front mec changed with how it moved.
The 7 speed f/mec moved out & forward at the same time i.e. out from the seat tube & forwards towards the front wheel (if you see what i mean)
The 8 speed f/mec ONLY moves out from the seat tube.

Hope thats some help??

 

[pigman]

Re:

The 105 champagne-finished front mech can be difficult to identify. When it was part of a 7 speed downtube levers group it had a different pull ratio to when it went 8 speed with STIs. They look very similar but work differently. I'm not sure if tricolour 6400 was similarly affected.

I don't know how your 9 speed front mech will work with a 8 speed chain - is the 9 spd cage narrower, meaning lots of rubbing and micro adjusting?

I'd just look for a 6 or 7 speed shimano front mech, there'll be dozens around

 

[foz]

Thanks Chris and pigman! I'm aware of the difference between the 7 speed and later shifters and mechs, just wondered if there were any more changes after that (is 9 speed different to 8, or are they all the same until the latest ones with the long lever arm?)

pigman - the 105 front mechs are actually quite easy to tell apart (the band on ones, anyway), even without looking at the model number on the inside cage: the 7 speed version has a "straight" front half of the clamp that sticks out from the non-drive side of the seattube. The later ones have a clamp that better wraps around the seattube