bobotech

At my bike coop, we end up with a lot of stuff that is older for obvious reasons.

Well something I have been wondering is this, are Suntour derailleurs compatible with Shimano indexing shifters. It would be nice if they were since we have a bunch of nicer older Suntour derailleurs that are in better shape than a lot of the crappy Wallyworld quality Shimano rear derailleurs that we have in our buckets but almost all modern crappy bikes that come in do have indexing shifters.

FBinNY 

To my knowledge they were not, at least the ones from 20 years ago weren't. But I believe that after SunTour folded, the new company using that name made some derailleurs that were Shimano compatible. I vaguely remember that one of these was something like RX-100. I don't know either way about current production because I've never used modern SunTour stuff.

ultraman6970

NO that I know of.

Jeff Wills

No. Not going to work.

xenologer

no
cable pull is different; in many cases cassete is different spacing for given spd too. ie need a suntour cassette with suntour derailer
stock up on friction thumbshifters if you want to use them
friction rocks, everything becomes compatible with everything. except SRAM rear derailers, but SRAM sucks anyway

possible experiment:
it is known that a suntour acushift 6spd shifter, will index a shimano rear derailer and shimano 7spd cassette (minus 1 cog)
does this imply the reverse?
will a shimano 7 shifter index a suntour accushift derailer on suntour acushift 6spd cassette?
Seems logical, but never tried it in that direction.

dsbrantjr

It might be worth trying those old parts. I have a 1993 Schwinn Crisscross with an original Suntour XCT Lite 7-speed rear der which works beautifully with a Shimano SL-M310 shifter and Shimano cassette. I did need to run the shift wire to the opposite side of the attachment screw (alternate cable routing) but it indexes perfectly now.

bobotech

Well I wanted to avoid stuff like alternate cable routing because we are a coop and sometimes it is just easier to avoid certain types of "fix its" rather than try to educate someone who has no idea how to work on a bike why they need to use an alternate cable routing or whatever.

Just must easier to say "Sorry, you need a Shimano brand rear derailleur rather than the Suntour" and dig up some other derailleur.

Bianchigirll 

I agree to a certain extent with Dsbrantjr. If you have time on your hands it is certainly worth toying with. If the RD in question is a Accushift compatible one and your shifter and FW/Cassette are matching it may work. I ran a 600 RD with a Suntour barcons and FW for a years with little trouble.

JohnDThompson 

Friction shifting = "no worries." Mix & match as needed.

bobotech

The suggestions to mix and match and play around and use friction shifting are normally awesome however you have to take in consideration that this is a bike coop. We don't have time to play around trial and error trying to get the perfect shifting. I was jsut unsure if Suntour rear derailleurs used the same kind cable pull and ratios as Shimano. As for friction shifting, you would be amazed at the amount of people who do not want friction shifting or who want to be bothered with changing out the shifters or even just learning how to shift using a friction shifter.

bradtx

RX-100 was a pretty darn good Shimano group, I still have some take-off calipers.

Brad

bradtx

bobotech, A bike co-op would seem an ideal atmosphere to task someone to test RDs and spreadsheet what works, A/B routing and etc. Otherwise it's the recycle bin or put up for sale.

Brad

Homebrew01

Why doesn't SRAM work with friction shifters ?

Kimmo

SRAM uses more cable pull, which makes its indexing more robust. I guess many friction shifters can't pull enough cable. Pretty sure filling the cable groove on the lever with epoxy would sort it.

+1.

Plus, coming up with novel combos is awesome. There's an old bloke who turns up at my co-op from time to time with one of the coolest pushies I've ever seen. His bike is a real bitsa, a total mishmash. Aside from the sexiest carbon fork I've ever laid eyes on, other nifty things include a young man's gearing (the guy must be pushing 80, and his lowest gear is a 42/21 or something) and his shifting. He's got Sachs Ergos shifting this weird Suntour RD with a freaky pulley-style actuation system that seems to missing from Disraeli Gears. Way cool.

fietsbob

>>> Maybe <<<

(just give it a try, live and learn, etc.)

Try using the friction shifting mode?






...

evets11

Older friction Suntour RDs (pre- Accushift) are INDEED compatible with Shimano index shifters. Cable pull ratio is 1:1 for vintage Suntour RDs AND Shimano index RDs. I hooked up several bikes with Shimano SIS DT shifters and index brifters with Suntour RDs and they indexed PERFECTLY. Accushift RDs have a different cable pull ratio. Sorry SUPER late to this thread.

xenologer

It's considered to be a 'faux pas'
to reopen a Zombie Thread in these forums

Yeah, some other forums react differently, but that's not how we do things here.

Retro Grouch 

Exactly what I was thinking: "Friction shifting is your friend." Cheaper too. Even if you have to buy new parts friction thumb shifters can be had for next to nothing. You can assemble a much more elegant beater bike for the same or less money if you're willing to forgo index shifting.

Retro Grouch 

Yeah, and next comes the "Use the search function" lecture.

Let me ask you this: The thread title and date are clear. If that's a big deal for you why can't you just skip over it? That's what I do.

IrishBrewer

Also, it seems especially appropriate in this instance because the new post is a dissenting opinion so if correct, could serve to dispel some bad info on a past thread that would serve a searcher poorly when seeking info on this.

JanMM

Depends. (Re: Zombie threads.)

Dave Mayer

Back to the question: will a Suntour derailleur index correctly with a set of STI (Shimano Total Integration) shifters....

As expected, there were a slurry of useless and pedantic responses that included the word: 'friction'. And references to various kludges that sidestep the issue.

The math never fails here. I have mixed and matched all forms of unholy derailleur/shifter combinations in the past. If the math works, then the shifting will work.

Keep in mind that there is a wide range of interpretation as to what constitutes: 'working' - i.e. acceptable shifting performance. In my experience, most riders are blissfully ignorant as to the operations of their bikes, and just assume that a drivetrain that constantly and randomly clatters between gears is 'normal'. My standard is that the drivetrain us completely silent when in-gear, and shifting is precise and fast - every time.

To the math: most indexing Shimano derailleurs have an actuation ratio of 1.67:1. That is, for every mm of cable pull, the derailleur travels 1.67mm. Suntour Accushift (indexing): 1.80:1. Doesn't match.

Suntour pre-Accushift: the ratios are all over the map. No consistency between models or model years, but the ratios are roughly 1.8-2.0:1. So a higher derailleur travel than Shimano, and all other current indexing systems.

Again: doesn't work. Don't waste your time on this..

BTW: I have about 20 pounds of high-end Suntour derailleurs in a bin somewhere. I've tried this stuff..

fietsbob

Friction shifting makes all sort of things compatible..

Dave Mayer

Indeed. I too work at a Co-op and I do not want to waste my or the clients time in random experimentation. The bigger issue is that the mechanic should KNOW if it will work before even starting. And he should also know WHY it will or will not work based on fundamentals and the math.

It is not good enough just to know it doesn't work based on a past experience. You have to know the WHY.

So: again ignoring repetitive idiotic references to 'friction', the reason WHY old Suntour derailleurs will not index with STI.. - it is due to the mismatches in cable pull and derailleur actuation ratios.

Andy_K 

I agree. I'm not usually a fan of zombie threads, but in this case I didn't look at the dates and as I was reading the comments, the new comment from evets11 flowed very well and provided interesting information. As a reader of this thread, it makes no difference to me whether this comment was written today or five years ago.