3speed

I've got a 90ish Trek 720 with the stock components mentioned. The brake levers are complete garbage. I'd like to just put on a set of brake/shifters that I have in the parts bin. I've read so much different info on mixing and matching this Suntour stuff. Anyone have any idea if this combo would work or not? Is the shifting difference in the derailer design or the shifters? If it's in the shifters, could I still use that derailer and just get a different freewheel to use with the Shimano shifters?

clubman 

6 or 7 speed? XTC was a great band (loved GO) but you likely mean XC Pro? Is it an Accushift freewheel? I'm also wondering what model of brakes are so bad. Rollercam? Pics?
It's been somewhat established that Accushift 7 speed shifters are needed for an Accushift 7 speed freewheel and that there's some latitude using Shimano indexed shifters with the 6 speed Suntour drivetrain. Or you can use some Suntour derailleurs with Shimano indexed drivetrains. Clear as mud, yes?

3speed

It's 7 speed. Thanks for clearing that up. I couldn't quite put that mess together from the threads I read. The brake levers are whatever came stock on the 90ish Trek 720. I guess I'll just try to come up with a cheap set of levers and use the Suntour shifting stuff.

alletcat

I got a 90 trek 750 that has suntour accushift xcm it has a shimano rear wheel it works fine...like that when I got it,

3speed

Sorry, I meant XCT. In any case, I've decided to use the Shimano shifters and Suntour derailer and add a Shimano freewheel. From what I've read, I think that should work.

zukahn1

Since most of the difference is in the freewheel you should be fine running a Accushift RD with a Shimano Freewheel and shifters.

3speed

Thanks. That makes me feel better about ordering the new freewheel.

PatTheSlat 

I've run a Shimano freewheel with a Suntour RD and accushift shifters with no problems, but I was under the impression that the Suntour and Shimano RDs had different cable pull ratios, so you couldn't mix brands with shifters/derailleurs.

pcb 

Can't hurt to try, but the derailleur geometry, cable pull ratios and shifting mechs are different, so it wouldn't surprise me if it didn't work well. Ditch the SunTour der for a Shimano an Bob's yer uncle.

dddd

I expect that whatever # of speeds that your Shimano shifters have, that the Accushift derailer will index a freewheel with fewer # of speeds.

7 or 8sp Shimano shifter should index a standard-width 6sp freewheel.

9sp Shimano shifter should index a 7 or 8sp freewheel/cassette.

So in other words, the Accushift derailer's actuation ratio is configured like a pre-1997 (pre-9sp) Dura-Ace derailer, and I remember a few fellow racers who used them as such.

Glennfordx4

Although it was a friction set up I was working with, I ran into problems yesterday on a build I am in the middle of, I have a Suntour VX RD, Shimano HG 6spd FW and a set of Shimano friction shifters from a Le Tour. There wasn't enough pull from the shifters to move the RD from 6th gear to 4th gear no matter how I set it up, switched to a cheap set of ST Friction shifters and everything played nice & shifted smooth, so there is something different between the two companies in the pull ratios.

Glenn

The Golden Boy 

Keep in mind, I've only used 6 speed...

My understanding is that (as far as 6 speed- the most forgiving) a Shimano FW can be mated with an Accushift derailleur and Accushift shifters and it'll work. I was not able to get a Shimano FW to work with a Shimano derailleur and Accushift shifters- even in 6 speed.

Accushift 7 speed is an entirely different beast- due to the difference in cable pull and spacing on the rear cogs. Personally, I wouldn't **** with it and just go Accushift or Shimano across the board- or Accushift shifters and derailleurs and a custom built cassette as described in mrmw's super Accushift thread. https://www.bikeforums.net/showthread...awk?highlight=

Also, Accushift a3040 is it's own beast- a3040 components need to be matched with a3040 components.

dddd

FWIW, all 6-speed freewheels are spaced the same, except for various maker's Ultra and Compact versions.

And you right about the 3040 series components, whether road or mountain type they have their own unique cable-pull and actuation ratio so must be paired as shifter+derailer.

I am at a complete loss to explain GlenFordX4's inability to get a Shimano friction shifter to pull any Suntour derailer across a 6 or 7-speed freewheel.
There should be more than enough cable pull from those shifters, just measure the shift lever's spool diameter to see, it's at least 17mm so should be more than enough, as even a 15mm spool will pull more than enough cable for any Suntour derailer (except maybe that model 3040).
Is the shift lever's throw perhaps being limited to only 90 degrees of movement?
Very strange!
Is the cable or housing possibly slipping somewhere?

John E

I bought my Schwinn with a 7-speed Accushift setup, including SunTour freewheel and thumb shifters. I always ran it in friction mode and recently made an easy wheel switch to an 8-speed Shimano cassette -- works like a champ.

Glennfordx4

There is just not enough travel in the Shimano shifter before it hits the stops, at first I thought I had the hub spacing wrong & set to far from the dropout but any closer & I would be hitting the dropout with the chain. I didn't think there would be a problem as they were stem mounted friction shifters I was using from a 74 Schwinn Le Tour which runs a Shimano made RD, it all worked good on the Le Tour, the only difference was I installed the VX RD once I moved the components over to a different frame. I am using new SIS cables & SS inner wire, everything is seated right and works great with the Suntour shifters installed. Weird!

I have also used a Shimano FW with 6 & 7spd Accushift with no ill effect.

Glenn

dddd

Glen, you hit the nail on the head by mentioning it's a stem shifter.

Like I hinted at, stem shifters don't move a full 180-degree arc the way a DT shift lever does. Usually its closer to only 110 degrees total throw.

I've used Schwinn Twin-Stick stem-shifters with an Allvit derailer modified to move fully across a standard 6-speed freewheel, and the throw (and cable pull) was just barely adequate.
This had the positive effect of limiting the overshift stress that the cable sees when you slam the chain onto the biggest cog, since the shifter bottomed out just as the lo-limit screw did. Luckily those Allvit derailers had an adjusting barrel.

PatTheSlat 

You certainly weren't doing anything wrong, just yesterday I tried setting up a 77 Le Tour with a Suntour GT rear derailleur, and there wasn't enough travel in the original shifters. Switched it to a Shimano RD and it was good to go.

3speed

Wow. A whole lot of info all of the sudden. Thank you all for clearing this up. Now I'm glad I worked a couple extra long days and didn't get a chance to order the freewheel. I guess I'm going to be ordering a new set of brake levers and using the original shifters and derailer. So it's the Derailer that causes the big problem... Good to know.