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Roadie with unshaven legs
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I tried to use 9-speed Shimano 105 brifters with my Suntour GPX rear derailleur and 7-speed Winner freewheel. After wasting an hour I stuck the downtube shifter back on. The distance the derailleur moved when I shifted through 8 gears is about the same as the width of the 7-speed freewheel. Obviously, some gears shifted fine but most of the time it just rattled and didn't shift. Maybe I needed to use a Shimano 9-speed cassette. I'll try it again this weekend and let you know.

The 8-speed Superbe and the 7-speed GPX should take the same amount of cable pull to shift through the gears as the rear freewheel spacing should be the same. The shifter barrel diameters should be the same as well so the derailleurs should require the same amount of cable pull to move the same distance.

Supposedly, the Suntour Accushift shifters set in Ultra mode should shift a Shimano rear derailleur on a 9-speed cassette with some thin shims added to the spacers on the two smallest cogs but I have not tried it. With this logic I figured the opposite would be true: the STI shifters should be able to shift a Suntour rear derailleur across an Ultra freewheel but this did not work.
 

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n00bsauce
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The derailleur doesn't care what shifters you use but the cassette sure does. As long as the brifters and cassette are compatible the derailleur should work.
 

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Mel Erickson said:
The derailleur doesn't care what shifters you use but the cassette sure does. As long as the brifters and cassette are compatible the derailleur should work.
This is not true. The three current indexed shifting systems (Shimano, SRAM and Campagnolo) all have different ratios of derailleur movement to cable travel. So, for example, matching a Campagnolo derailleur to a Shimano 9spd shifter will not index properly on a Shimano 9spd cassette.

Suntour MTB derailleurs had similar ratio of derailleur movement to cable travel as Shimano. I don't know if their road derailleurs were also similar.

Here is an excellent article on mixing and matching shift systems: Article on Rear Shifting
 

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n00bsauce
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But we're talking 8spd stuff here. I guess I should have clarified.
 

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Mel Erickson said:
But we're talking 8spd stuff here. I guess I should have clarified.
You can't mix one manufacturer's derailleurs with another manufacturer's shifters and cassettes for 8spd either. Even if the shifter and cassette match each other, you still need to use a compatible derailleur for correct indexing.
 

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There isn't a complete lack of compatibility--I'm running Chorus derailleurs with Record Ergo in combination with Ultegra hubs and an XT cassette, everything 8sp, on a 'cross bike. No re-routing of the cables at the derailleurs, no cable-pull modifiers (J-tek et al), no spacers. All I had to do was fiddle once with the barrel adjuster on the rear derailleur and I was set. No skipping, no jumping, no "almost right" shifts--it just works. ...and for the record, I tried the reverse once, out of curiosity--Campy hub/cassette with 8sp 105 derailleurs and brifters, and that was good, without any tweaking, too. Theoretically, there should have been misalignments with both combinations, but I'm guessing the 8sp chains were sufficiently forgiving to get around spacing issues.

As for the Suntour/Shimano pairing, I'd think that if the brifters and the number of cogs are in agreement, it should work. I've used Suntour XC Expert thumbshifters (in index mode) with an XT mech/cassette, and that works fine, but while I would think the road stuff would have similar actuation ratios, I couldn't verify it.
 

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n00bsauce
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I've had a lot of experience with Suntour/Shimano combos on a variety of bikes. I've never been shut out. I agree, the newer stuff is a lot more fussy and certain combos don't work well at all. But, most 8spd and older stuff can be made to work pretty good, many times very good. Suntour derailleurs were good stuff and very forgiving.
 

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Roadie with unshaven legs
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Mark McM said:
Suntour MTB derailleurs had similar ratio of derailleur movement to cable travel as Shimano. I don't know if their road derailleurs were also similar.

Here is an excellent article on mixing and matching shift systems: Article on Rear Shifting
For the sake of this discussion I will follow the following conventions:
We are talking about 8-speed indexing systems
Derailleurs are high-normal (if the cable were to break it would shift your bike to the tallest gear)
On an 8-speed 12-23 freewheel/cassette, the 23T gear is first, the 21T gear is second, ... the 12T gear is eighth.

Back when Shimano and Suntour were designing their indexing shift systems they had to overcome a common problem: the cable pull moves the derailleur a different amount for the same amount of pull depending on which gear you are in. In other words, the derailleur cage moves 5mm shifting from first to second but it moves 5.5mm shifting from fifth to sixth. Shimano and Suntour took opposite approaches to resolve this same problem: Shimano varied the distance between the clicks to compensate while Suntour varied the cog spacing on the freewheel. According to this website, the difference in gear spacing between first/second, second/third, third/fourth, fourth/fifth are the same between Shimano and Suntour 8-speed systems. Where we run into trouble is that the gear spacing between fifth/sixth, sixth/seventh, seventh/eighth is .5mm more per gear. This means that by the time you reach eighth, the gear spacing will be off by 1.5mm. This is enough for the system to not work well at all.

The URL listed in the quote is nice but it does not show how Suntour compares to the others listed.

This morning I decided to try mounting the cable via the "Hubbub" method. The results were that I was able to shift just fine front first through fifth on my 7-speed freewheel but then the shifting went out the door for the next two gears. I'm now thinking that I should be able to get this to work if I were to use a Shimano 8-speed cassette with the even spacing with my setup (GPX rear derailleur, 105 brifters).

A Suntour Accushift downtube shifter should be able to shift a Suntour rear derailleur over a 7 or 8-speed Shimano cassette provided you add additional spacers between the gears starting after fifth. Looking at the link I provided, the same argument can be said that the same downtube shifters should be able to shift a Shimano rear derailleur (non-early DA) over a 9-speed cassette with spacers between the gears starting after either fifth or sixth.

For russkat, I would say that you can try using the Superbe rear derailleurs with the Shimano brifters if you use a Shimano rear cassette and freehub. If you want to wait I just might try that combination this afternoon after I make a run to the LBS to get an 8-speed cassette.
 

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Roadie with unshaven legs
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Just a follow-up to my last post:

I bought a Shimano 8-speed cassette (HG90 12-25 - my legs aren't what they used to be) and gave it a twirl. Granted, I just mounted the cassette onto a freehub without the rim nor spokes in place, but it seemed to work quite well after I adjusted the cable and the high/low-limits. The cable was mounted the way Suntour intended as I think my attempt at doing the Hubub mounting wasn't quite right the first time around. I was watching the gap between the outer cage and the chain and it seemed to be right around 1mm from first through eighth gear regardless of which chainring I had the front on. A compact 9 might work if you play with the mounting of the cable on the derailleur. I used a fairly new SRAM 8-speed chain for this test.

Now I need to buy another rim to build that freehub up!
 

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n00bsauce
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The Shimano brifters, Superbe derailleur and Shimano cassette will work, I've tried it. Even though spacing is off by 1.5 mm in fifth through eighth you can compensate with your barrel adjuster by making the shifts in the middle of the cassette a tiny bit off. It takes some fiddling and patience but I've gotten it to work acceptably (my acceptable may be different from yours. Some people can't accept anything but extra sharp and crisp shifts while others are satisfied with a bit of lag). Actually helps to have an older derailleur with a little bit of slop in it, too. It gives you just a little bit more "adjustability".
 

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Roadie with unshaven legs
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Mel, I think I was pretty much saying that in my last two posts (Suntour derailleur, Shimano brifters and cassette).

I could not wait so I took apart an old 36 spoke rear wheel I wasn't using so that I could swap out the Campy freewheel rear hub for a Shimano 7-speed freehub. I built it, tensioned it, trued it, slapped the new cassette on it minus the 25T cog and spacer, adjusted the derailleur low limit screw so that I would not drop the chain into the spokes then took it for a ride. Shifts like a charm!
 

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russkat said:
Will 8sp Suntour Suberbe Pro RD work with STI brifters?

Thanks
Derek
I am using a ten year old Suntour XC Pro RD with my nine speed STI shifters, and a nearly new Deore XT RD with my eight speed Suntour thumbshifters and a eight speed Shimano cassette.
 
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