no motor?

The bike was purchased new years ago by a couple that is friends with my girlfriend, and was purchased by my girlfriend about 3 years ago from the wife who was downsizing her house a few years after the husband passed away. It had sat long enough to need new tires, tubes, brake pads, cables etc... and I also replaced the grip shifters then after a discussion about how bad they were. My girlfriend had them on her previous bike and liked them inspite of their shortcomings and wanted them same thing for this bike. But after riding with the gears not shifting for long enough she's decided she wants something that actually works but doesn't want trigger shifters or index shifters, she wants grip shifters that shift one gear with one click. And she doesn't want to try and finesse them into working by twisting the grip more after it hasn't shifted.The current shifters are Sram MRX comp and the derailleur is a Suntour XCE shifting a 7 speed triple. What grip shifter would work with these components and do what she wants?

The bike is a 750, sorry for the typo in the title I can't fix.

Andrew R Stewart 

SunTour ders and shifters had their own indexing cable pull amount, as well as it's own cog to cog spacing. So any mixing with Shimano spec parts (like the current MRX shifters on the bike) is a path to frustration. You get sort of/kind of function that seems like all should work but not quite.

As far as the bike goes I would replace the SunTour stuff with Shimano or Microshift. I suspect your rear wheel uses freewheels, not cassettes, so a 7 speed currently available freewheel should work without other issues.

The next issue is your GF not wanting to do the work to shift gears well. The two best solutions for a rider who refuses to learn how to do the small "over shift" that a der system generally wants (to shift cleanly) are either an electronic system or an internal geared hub. Of course with a miss matched current system it's no wonder that she has shifting issues and is frustrated to the point of speaking up. Andy

no motor?

Thanks!

Crankycrank

+1 with what Andrew says but as far as I can determine the Suntour derailleur has a 1:1 cable pull which will work with SRAM gripshifters or any that have the same cable pull but you would have to change the freewheel to a Shimano/SRAM spaced since as mentioned the Suntour freewheels had various spacing between the cogs that is only compatible with Suntour shifters and will create the sloppy shifting your girlfriend describes. Also, generally the better (i.e. more $$) the shifters the cleaner the shifting.

bikemig 

Also cheap is good. Sun race makes some very decent, inexpensive friction thumb shifters if you can find them. I used them to rehab a late 80s Rockhopper for my nephew.

70sSanO

SRAM made Grip Shift for Suntour in the 90’s. You can still find them occasionally on eBay, mostly used sometimes NOS. Unfortunately the prices of “any” older parts are ridiculously high as people are looking to bring old bikes back to life with limited older parts available.

If your gf likes the MRX shifter, except for shifting performance, just get a Shimano rear derailleur and, hopefully, a Shimano compatible freewheel. Shimano and Sunrace make 7 speed freewheels.

If it is a Suntour cassette, that is a tougher nut to crack.

John

hokiefyd 

For twist shifters, I like Shimano's "upper" line of the Revoshift (SL-RS45 or -RS47). These are available in 3x7 and work very nicely. They have a "soft touch" shift feel to them so they're not quite as "notchy" as other twist shifters. They will require a Shimano SIS derailleur to work, however. An RD-M310 or RD-M360 would work nicely.

dmark 

1990 has a freewheel (easy swap) but my 91 750 is a cassette so needs a wheel to run Shimano. I am keeping the 90.