I want lower gearing but have Suntour parts.

[Frankenbike]

I think that you may find 24T gets you low enough, but if not, personally I'd just get a 22-32-42 from Spa.

Hey guys,
just wanted to let you know that I got the smaller chainset on 42 32 22 and it feels really good. I may need a new front mech but otherwise the job seems like a good'un. Thanks for helping me in coming to a decision.

[JohnW]

...............I got the smaller chainset on 42 32 22 and it feels really good. I may need a new front mech but otherwise the job seems like a good'un...............

Be sure to get the right one - I was sold the wrong Shimano Ultegra about 10 years ago............the cage plate profiles and sizes are specific, and each to a limited range of chain-ring ranges. This was discussed in another thread a few months ago - and Brucey clarified the situation.

[andrew_s]

At least he's got bar end shifters, so he's only got to consider outer plate curvature and inner plate drop, and not cable pull.
Too much inner plate drop, and the inner plate hits the side of the middle chainring when you're trying to shift onto the outer. It's usually specified as a minimum middle-outer tooth difference.

I'll suggest a matching SunTour XC Pro front mech. Mine says (or did before the labels fell off) Max chainring 48T, Microdrive compatible. I'm using it with 46/36/20, on a TA Zephyr.

[JohnW]

At least he's got bar end shifters, so he's only got to consider outer plate curvature and inner plate drop, and not cable pull.
Too much inner plate drop, and the inner plate hits the side of the middle chainring when you're trying to shift onto the outer. It's usually specified as a minimum middle-outer tooth difference.....................

Been there, done that!

[gaz]

At least he's got bar end shifters, so he's only got to consider outer plate curvature and inner plate drop, and not cable pull.
Too much inner plate drop, and the inner plate hits the side of the middle chainring when you're trying to shift onto the outer. It's usually specified as a minimum middle-outer tooth difference.

For the linked Suntour XC Pro front mech and various other Suntour MTB triples from the same period, the total capicity is 24T and the recommended outer middle drop is 7-11T.

[Frankenbike]

I'll suggest a matching SunTour XC Pro front mech

So far so good. I do have an xc Pro front Mech which seems fine with the smaller chainset. I had to change bottom bracket to bring the chainset in closer to the frame. There were problems setting up the rear mech but that turned out to be a bent rear mech hanger.
I haven't tried shifting under load yet, but the bike will make it up any hill now.

[Brucey]

IIRC the final version of SunTour XC was a 'microdrive' groupset.

Those FDs are purpose made to shift well on ~42-32-22 chainset, but there is a chance that the tail of the FD will interfere with the chainstay on a bike with 700C wheels, because the chainstay angle is different.

cheers