Hi

Excuse me if this has been mentioned before.

Am I right in thinking that a 7 speed Shimano tiagra shifter will not work with a 9 speed cassette ? I think the rear mech is also tiagra but not sure if its a 9 speed or not. Although I don’t think that matters much.

I’m thinking the ratios our out. If someone could elaborate or confirm (or otherwise) that would be great.

Cheers Rodders.

Really? 😯

I think all Shimano stuff up to 9 speed to compatible, but the paths diverged when MTB stuff went 10 spd.
I think you can use 10 spd road stuff on MTB 9spd still.

I mustn’t have it set up correctly then. I can set it so it shifts smoothly going up but it won’t drop.
Assuming they are compatible.

8 cogs from a 9 speed cassette fits almost perfectly on a 7 speed hub.

Hence my guess is 7sp shifters don’t work on 9sp cassettes.

Ye Olde Worlde friction levers, with the SIS mode turned off would probably be fine though.

Surely 9 speed shifters work with a 7 speed cassette, not the other way round?

I was thinking that Woody. Ive tried adjusting the H/L screws so I use 7 gears (discounting the top two sprockets) but still shifts poorly. Im thinking the click ratios are different in the shifter or the spacers in a 9 speed cassette are different.
Either way it ain’t working.
Think a new 9 speed shifter is in order.

I think you’re correct.

Tiagra has just gone to 10sp this year, so the 9sp shifters will either be out of stock, or in the bargain bin, or 2nd hand off ebay etc.
Or Sora might be 9sp still?

No, a 7 speed shifter will not work properly with a 9 speed cassette. The cassette spacing on 7 and 9 is different. You could get away with a 7 speed shifter and 8 speed cassette but obviously only be able to use 7 of the sprockets.

I thought the sprocket spacing on the cassette was the same for 7 & 9 spd? If he’s using a compatible mech and shifter it should be ok?

When they say stuff is compatible, they don’t mean the shifters. 7 speed shifters only have 7 stops of course, so each click pulls more cable than it does for 9 speed.

The cogs are closer together on 9sp so they can pack more in a similar space.

I THINK the spacing stays the same for 9 and 10, but I’m pretty sure that the spacing on 7 and 8 is slightly different. 7sp thumbshifters mostly worked on 8sp cassettes, but it wasn’t very good.

I thought the sprocket spacing on the cassette was the same for 7 & 9 spd? If he’s using a compatible mech and shifter it should be ok?

No, same for 7-8, cassette is 3mm wider on 8. 8/9 are the same width, they reduced spacing for 9, hence narrower chains.

10 speed is very slightly narrower over all for road stuff and thus narrower spacing.

I THINK the spacing stays the same for 9 and 10

A 10 speed road cassette has 1 extra sprocket and is 1mm shorter than a 9 speed so no, the spacing is not the same.