Will 7/8 speed shifter work with 6 speed freewheel?

Pulled the wife's old mountain bike out of the cellar for her annual holiday bike ride coming soon, only to find the front shifter casing busted (plastic fatigued). The bike is a 6 speed 1980's Saracen (when they used to make quality bikes) with Shimano Exage kit. Time to get some new pod shifters - Q: will a 7 or 8 speed work? I've looked at Chris Juden's article here, but can't decide if it will.
 

andrew_s

Guru
Location
Gloucester
Not as intended.
A 7speed shifter will move the cable 5mm per click. 6 speed sprockets are 5.5mm apart.
So if you set the cable tension so it's correct in the middle of the cassette/freewheel, it will be 1.5mm short of reaching the correct position for the top or bottom gear sprockets. That will be too far off to work.

The only entry on CJ's tables that would work is a 7 speed Shimano shifter with an old Dura-ace rear mech. That's no good as an old Dura-ace mech will be just as hard to find as a 6 speed shifter, and the road mech won't like large sprockets.

Probably the best bet is to use a Jtek model 2 Shiftmate from SJSC.
This is sold for using a 9 or 10 speed shifter with an 8 or 9 speed cassette (or vice versa). According to CJ's table the ratio between 6 and 7 speed cable pulls is much the same as that between 8 and 9 or between 9 and 10, so it should work.
 

TheDoctor

Europe Endless
Moderator
Location
Stevenage
Personally, I'd just replace the shifter. My LBS can sort this for around £20 in parts, assuming you replace both.
A 7 speed won't work, as above.
It's up to you, but either Gripshifters or the Tx50 shifters will get you sorted, whichever you prefer.
 
OP
N

New Horizon

Veteran
Thanks both, confirmed what I thought. Those Tx50's look just the job - had looked around for new 6 speed shifters but couldn't find any.
 
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