Suntour 7 speed / Shimano 7 speed: Compatible?

[Hell and High Water]

So far I've received about twenty VERY AUTHORITATIVE answers to this
question.

All of them seem to disagree....



I have an older bike that originally came with Suntour components.
Downtube shifters, double front, seven back.

I wanted to try STI shifters, so a LBS put on Shimano Sora
brake/shifters. They said the Suntour rear
derailleur/freewheel/chain/etc. were good.


Worked pretty good, but I had some problems shifting. Chain searching
for gears. If I went up one and it searched, I'd go up two, then back
one, and it was fine.

Anyway... *some* problems.



Second LBS said the problem was the rear derailleur. Had to be Shimano
to work. (Again, freewheel/chain were good.)


Went with the Shimano Sora rear derailleur and the bike shifts much
better. I felt like that made a noticeable improvement.

However, every once in a while there's a weird SKIP on the back cog.
Almost like something missed a tooth or two.

Someone in a newsgroup told me that the Shimano freewheel and the
Suntour freewheel are different, and I should go all Shimano.


(BTW, none of this is exactly killing me financially. This level of
gear is not terribly expensive.)


I would feel great about going all Shimano, but I would be a bit
irritated if I still had that skipping.


Any thoughts/suggestions?


I looked around Sheldon's page, but could not find this exact subject.


TIA!

-Bob

 

[still me]

On Wed, 15 Aug 2007 13:24:03 -0500, Hell and High Water
<[email protected]> wrote:

>However, every once in a while there's a weird SKIP on the back cog.
>Almost like something missed a tooth or two.

Any chance you have a tight link in the chain?

 

[Mark]

Hell and High Water wrote:
> So far I've received about twenty VERY AUTHORITATIVE answers to this
> question.
>
> All of them seem to disagree....
>
>
>
> I have an older bike that originally came with Suntour components.
> Downtube shifters, double front, seven back.
>
> I wanted to try STI shifters, so a LBS put on Shimano Sora
> brake/shifters. They said the Suntour rear
> derailleur/freewheel/chain/etc. were good.
>
>
> Worked pretty good, but I had some problems shifting. Chain searching
> for gears. If I went up one and it searched, I'd go up two, then back
> one, and it was fine.
>
> Anyway... *some* problems.
>
>
>
> Second LBS said the problem was the rear derailleur. Had to be Shimano
> to work. (Again, freewheel/chain were good.)
>
>
> Went with the Shimano Sora rear derailleur and the bike shifts much
> better. I felt like that made a noticeable improvement.
>
> However, every once in a while there's a weird SKIP on the back cog.
> Almost like something missed a tooth or two.
>
> Someone in a newsgroup told me that the Shimano freewheel and the
> Suntour freewheel are different, and I should go all Shimano.
>
>
> (BTW, none of this is exactly killing me financially. This level of
> gear is not terribly expensive.)
>
>
> I would feel great about going all Shimano, but I would be a bit
> irritated if I still had that skipping.
>
>
> Any thoughts/suggestions?
>
>
> I looked around Sheldon's page, but could not find this exact subject.
>
>
> TIA!
>
> -Bob
>
Suntour freewheel cogs in a seven-speed freewheel are not all spaced the
same. For example, the spacing between the two smallest cogs differs
from the spacing between the two largest, IIRC. SunTour shift levers
accounted for this.

Shimano STI shifters assume equal spacing between cogs (I think they
mostly assume a freeHUB, hence the equal spacing). Hence an
incompatibility. The combination /may/ be made to work tolerably, I
don't know, and that will definitely depend on your notion of
"tolerable" - could mean avoiding one or two of the gears, intolerable
by most accounts.

Note that SunTour "regular" six freewheels (vs. the narrow spaced
"ultra-sixes" and all sevens) were spaced uniformly enough that they
would work with Shimano's original six-speed indexed downtube shift
levers and derraileurs (I know this from experience).

Finally, I think the last Suntour freeHUB cassettes made before SunTour
went belly-up, and probably the ones being made now by SR-SunTour (which
reportedly has no connection to the older company except in name)
were/are equally spaced. In the case of SunTour, I think this was for
Shimano compatibility. I invite correction by those who know this last
situation better than I.

Short answer: Probably won't work well at all. Much as I shudder to
say it, all Shimano is probably your best bet here.

Mark "SunTour lover" J.

 

[Nigel Cliffe]

Hell and High Water wrote:
> So far I've received about twenty VERY AUTHORITATIVE answers to this
> question.
>
> All of them seem to disagree....
>
> I have an older bike that originally came with Suntour components.
> Downtube shifters, double front, seven back.
>
> I wanted to try STI shifters, so a LBS put on Shimano Sora
> brake/shifters. They said the Suntour rear
> derailleur/freewheel/chain/etc. were good.
>
> Worked pretty good, but I had some problems shifting. Chain searching
> for gears. If I went up one and it searched, I'd go up two, then back
> one, and it was fine.
>
> Anyway... *some* problems.

> Second LBS said the problem was the rear derailleur. Had to be
> Shimano to work. (Again, freewheel/chain were good.)

> Went with the Shimano Sora rear derailleur and the bike shifts much
> better. I felt like that made a noticeable improvement.
>
> However, every once in a while there's a weird SKIP on the back cog.
> Almost like something missed a tooth or two.
>
> Someone in a newsgroup told me that the Shimano freewheel and the
> Suntour freewheel are different, and I should go all Shimano.


I've a bike with old (circa 1990) Suntour 7 speed rear, using "Commander"
shifters.


The rear freewheel block (it is a screw-on) for Suntour has different
spacing to a Shimano rear block. Not by much, but its different. The Suntour
was not evenly spaced, for some reason they put some cogs closer than
others. The shifters matched this.

In practise, with Suntour blocks no longer available, I find that a Shimano
rear block shifts OK with a Suntour rear mech and shifters provided the
adjustment is done carefully (I have a new Suntour rear mech on the bike,
bought last year as new old stock, this shifts much better than the old
well-worn example I had previously).
But I have the advantage of an cable trimmer (where the down-tube shifter
would be), plus the option to go back to friction shifting if need be.


As for your skipping at the back, start with the obvious:
a) chain wear (stretch)
b) fitting new chain to worn sprockets
c) tight link in chain or faulty quick-link.

Then move on to consider if it is alignment/adjustment.


Given where you've reached - Shimano shifter, Shimano rear mech, I would get
a Shimano rear block as well; they're still around in Europe in limited
sizes (14-28 seems to be common here).
Check your front rings carefully for wear, they may be causing the problem
with the chain.





- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

 

[Qui si parla Campagnolo-www.vecchios.com]

On Aug 15, 12:24 pm, Hell and High Water <[email protected]>
wrote:
> So far I've received about twenty VERY AUTHORITATIVE answers to this
> question.
>
> All of them seem to disagree....
>
> I have an older bike that originally came with Suntour components.
> Downtube shifters, double front, seven back.
>
> I wanted to try STI shifters, so a LBS put on Shimano Sora
> brake/shifters. They said the Suntour rear
> derailleur/freewheel/chain/etc. were good.
>
> Worked pretty good, but I had some problems shifting. Chain searching
> for gears. If I went up one and it searched, I'd go up two, then back
> one, and it was fine.
>
> Anyway... *some* problems.
>
> Second LBS said the problem was the rear derailleur. Had to be Shimano
> to work. (Again, freewheel/chain were good.)
>
> Went with the Shimano Sora rear derailleur and the bike shifts much
> better. I felt like that made a noticeable improvement.
>
> However, every once in a while there's a weird SKIP on the back cog.
> Almost like something missed a tooth or two.
>
> Someone in a newsgroup told me that the Shimano freewheel and the
> Suntour freewheel are different, and I should go all Shimano.
>
> (BTW, none of this is exactly killing me financially. This level of
> gear is not terribly expensive.)
>
> I would feel great about going all Shimano, but I would be a bit
> irritated if I still had that skipping.
>
> Any thoughts/suggestions?
>
> I looked around Sheldon's page, but could not find this exact subject.
>
> TIA!
>
> -Bob

Puit that $20 shimano HG freewheel on there, adjust RD and go ride.

 

[Hell and High Water]

In article <[email protected]>,
[email protected] says...
> On Aug 15, 12:24 pm, Hell and High Water <[email protected]>
> wrote:
> > So far I've received about twenty VERY AUTHORITATIVE answers to this
> > question.
> >
> > All of them seem to disagree....
> >
> > I have an older bike that originally came with Suntour components.
> > Downtube shifters, double front, seven back.
> >
> > I wanted to try STI shifters, so a LBS put on Shimano Sora
> > brake/shifters. They said the Suntour rear
> > derailleur/freewheel/chain/etc. were good.
> >
> > Worked pretty good, but I had some problems shifting. Chain searching
> > for gears. If I went up one and it searched, I'd go up two, then back
> > one, and it was fine.
> >
> > Anyway... *some* problems.
> >
> > Second LBS said the problem was the rear derailleur. Had to be Shimano
> > to work. (Again, freewheel/chain were good.)
> >
> > Went with the Shimano Sora rear derailleur and the bike shifts much
> > better. I felt like that made a noticeable improvement.
> >
> > However, every once in a while there's a weird SKIP on the back cog.
> > Almost like something missed a tooth or two.
> >
> > Someone in a newsgroup told me that the Shimano freewheel and the
> > Suntour freewheel are different, and I should go all Shimano.
> >
> > (BTW, none of this is exactly killing me financially. This level of
> > gear is not terribly expensive.)
> >
> > I would feel great about going all Shimano, but I would be a bit
> > irritated if I still had that skipping.
> >
> > Any thoughts/suggestions?
> >
> > I looked around Sheldon's page, but could not find this exact subject.
> >
> > TIA!
> >
> > -Bob
>
> Puit that $20 shimano HG freewheel on there, adjust RD and go ride.

Done

Done

and

DONE!

THANKS!

-Bob