Does this sound right for front mech cable pull?
Manc33
Posts: 2,157
I was just trying to measure the cable pull on a Shimano SLX triple front shifter (M660 just as an example) and it seems to be:
SL-M660
Granny to middle: 12mm
Middle to large: 9mm
Does any Shimano documentation tell you this?
Anyone know if those are the right numbers?
Then I am going to measure my flat bar shifter and actually find out once and for all if the cable pull is different.
Just asking in case anyone knows for sure what mm it is.
EDIT: Measuring a R440 "flat bar" shifter the figures aren't that different due to the trimming:
SL-R440
Granny to middle: 8.5mm (untrimmed)
Middle to large: 9mm
If I click the trim up it makes it about 11.5mm/9mm.
So I would suggest that flat bar shifters and MTB shifters do have the same cable pull meaning "flat bar front road mechs" have a mountain bike cable pull.
The reason for having to have loose cable on the granny ring with a MTB shifter is the lack of trim, so a MTB shifter is always "trimmed up" thus causing rubbing on middle>large sprocket thus needing the barrel adjuster winding out to compensate. You're only compensating for that trim, the cable pull itself appears to be identical, but without the facts I am only guessing at measuring it.
Now whats bugging me is why road bike triples have a trim function and mountain bikes don't. :shock: So it is just an added feature thats not actually needed then? I ran my road chainset with a MTB shifter and the clicks were in the right places as long as you had the cable loose on the granny ring. When push comes to shove I would rather do away with the trim and have loose cable. The granny ring is probably used not even 0.5% of the time I am riding anyway.
SL-M660
Granny to middle: 12mm
Middle to large: 9mm
Does any Shimano documentation tell you this?
Anyone know if those are the right numbers?
Then I am going to measure my flat bar shifter and actually find out once and for all if the cable pull is different.
Just asking in case anyone knows for sure what mm it is.
EDIT: Measuring a R440 "flat bar" shifter the figures aren't that different due to the trimming:
SL-R440
Granny to middle: 8.5mm (untrimmed)
Middle to large: 9mm
If I click the trim up it makes it about 11.5mm/9mm.
So I would suggest that flat bar shifters and MTB shifters do have the same cable pull meaning "flat bar front road mechs" have a mountain bike cable pull.
The reason for having to have loose cable on the granny ring with a MTB shifter is the lack of trim, so a MTB shifter is always "trimmed up" thus causing rubbing on middle>large sprocket thus needing the barrel adjuster winding out to compensate. You're only compensating for that trim, the cable pull itself appears to be identical, but without the facts I am only guessing at measuring it.
Now whats bugging me is why road bike triples have a trim function and mountain bikes don't. :shock: So it is just an added feature thats not actually needed then? I ran my road chainset with a MTB shifter and the clicks were in the right places as long as you had the cable loose on the granny ring. When push comes to shove I would rather do away with the trim and have loose cable. The granny ring is probably used not even 0.5% of the time I am riding anyway.
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