jzr756

Hello all. Just went completely through (mechanically) my new to me 88' Schwinn Impact MTB,a very cool vintage bike. (in my mind never the less)LOL. In any event, the original rear derailleur is a Suntour Alpha 3040. So I'm thinking changing up to a NOS Cyclone 7000 or XCD6000. What do you guys think? Should/will this make for a noticeable improvement in "shift quality" so to speak? Does have a intermittent poor shift going from 3rd to 2nd. made the barrel adjustment every which way with no improvement.. still like to get your thoughts on making the upgrade.

masi61

How many cogs on your rear cassette? Is it a proper Accushift spaced freewheel or cassette? Also, how is your cable, housing, chain and cassette/freewheel cogs? Anything that might need to be replaced since it is worn off.

Kontact

I had a 3040 - it is a competent derailleur, little different than the Cyclone, just with heavier materials. If there is something wrong with yours, it is not the quality or design. Lube it, lube or replace the cables, check the B tension and check your hanger straightness.

jzr756

Hello Just noticed your reply , Thanks! forgot to provide a few more details. Freewheel is also Suntour Accushift. hard to tell darn imprint is so small .Looks like Alpha also. 13-30 freewheel. 6 speed. Cables, housings new. Index/friction shifter.

jzr756

Thanks Kontact, Sort of figured it was more of a durability characteristic between them all to a degree? Really no difference in performance between the three? Yeah lubed and cleaned the poor thing to death. No B screw in sight nothing more than a plastic cover in its place. Hanger ,dropouts everything appears to be parallel/straight. Just the upper and lower jockey/guide wheels look a bit dry an brittle.

Kontact

I see that now - then your "B screw setting" essentially comes from chain length. I was basically suggesting that maybe your upper pulley is running either too close or too far from the cogs. You might also look at the state of the pulleys.

Not a durability thing, just weight.

maddog34

i'd guess that your 2-3 shift issues are more slop related... check for play at the knuckles/pins of the derailleur body, and the main pivots too...

i see more good condition V-GT suntours than any other style....they just keep going.
and any NOS or VGC shimano Deore LX, DX, and XT Ders will work well too.

whatever you choose, get a mid or long cage der.
Cyclone Rear ders are almost always a Short cage, Road style.

jzr756

OK,, the B screw setting / dimension is set by chain length. Every thing else I have does include one (the "B" screw that is) Thanks for schooling me on that. I did notice the pulleys didnt look in the best of shape.

70sSanO

I assume you’re using Suntour index shifting since shifting from 3rd to 2nd should not be any more of a problem than 4th to 3rd for friction shifting.

If this is correct, lubing cables with 30+ year old housing may not help at all.

Before you buy any rear derailleur you need to know if it can handle a 30t max cog. Just because the rear derailleur is an upgrade doesn’t mean it will work with your setup. I’m not sure a Cyclone 7000 will work. The XCD6000 might, but I can’t find any specs on it.

John

Mr. 66

I don't think you will improve performance much swapping things out. You may need to flush out the shifters, I am not a big fan of those shifters. At best I feel that those are inconsistent. Do make sure that the shifters are compatible with the rd. The 3000 may have a different pull lengths

Kontact

All Accushift derailleurs have the same pull ratios.

Mr. 66

No, that's not true for the road alpha 3000. Those have its own shifter that's not compatible with the others

KCT1986

Here is excerpt from a large Suntour doc, provided to attempt to assist techs to solve shift issues in the original Accushift system. Not sure if the OP's setup is from the early Accushift lineup (so FWIW).

70sSanO

I believe this is from a Suntour 1988 catalogue...

https://www.equusbicycle.com/bike/sun...20-%200007.pdf

The shifters appear to be thumb shift levers, RH - IFC friction/index. I think the X-Press came out a couple of years later.

John

Kontact

Dunno what to tell you, but my first nice bike was a Raleigh 420 with an Alpha 3000 RD and 6 speed index stem shifters, which I replaced with Suntour 6 speed index barcons and great shifting.

I see all the documentation about it, but the geometry change Suntour refers to may not be pull ratio, but over-shift.

But it is an exaggeration to say that they are incompatible. My bike worked with mixed components very well.

70sSanO

If I were the OP, I would try shifting in friction mode to see if everything shifts fine,if there are no issues I’d replace the cables and housings wirh Jagwire. If there are still issues with the 3rd to 2nd I would see if the freewheel is worn out.

I would replace the cables and housings with Jagwire and install a Shimano or Shimano compatible 6 speed hyperglide freewheel.

Too many years removed from Suntour, but I think the Accushift 6 speed uses the same cog spacing as Shimano.

John

Kontact

All indexed six speed spacing with the same 5.5mm. 7 was universally 5.0. Suntour, Shimano, Campy, Sachs, Giepemme. Things only go weird at 8.
(Exception for Suntour Microdrive 7, which was based on Microdrive 8, and would still work fine with other seven speed gear.)

Dave Mayer

Confirmed. Check the Suntour Tech Bulletin #21 page 2. Due to the unique derailleur design and geometry, Alpha-3000 series shifters and derailleurs must be matched.

Hobbling together fundamentally mismatched parts that results in clattery inconsistent shifting is not evidence that something 'works'.

Kontact

I didn't hobble anything together. I installed a brand new set of Barcons on a like new Raleigh with a Alpha 3000 rear derailleur and adjusted it normally. This was in 1988. Then I rode that bike for season and built a Campy Syncro bike from scratch.

People have very authoritatively told me that ISO and JIS taper are the same angle, but I actually matched them up and they aren't. There seems to be a lot of cycling stuff like that, where people read something and make assumptions. But didn't actually try it.

When did you combine an Alpha 3000 part with an Accushift part, Dave? Which component has the longer pull ratio?

jzr756

Hello John thanks for finding and posting the page out of the 88' catalog. I had located the page couple days back .search as I may I couldn't find it again. That page is exactly what got me headed in this direction, in as much as leaning toward supposedly going to a higher level in Suntour's product range. Found a video where this guy changed up from 3000 series to Cyclone 7000 said he felt a significant improvement in shifting so that video got me going as well. Also from the part description the Alpha 3040 seems just a step above the 2K/3K series not sure if that's good or bad ? So in light of the afore mentioned and the poor 3rd to 2nd shift issue thought it would be nice to have a NOS part back there . In any event, strange how all other shifts are nice and smooth going 6-5-4-3 then 3-2 I have to nudge the shifter forward just a tad in index mode to complete the shift. So as you mentioned I'm thinking in friction mode it would most likely shift just fine. The only other issue I found with the existing derailleur aside from the dry brittle jocky/pulley wheels ( not sure of correct nomenclature) is the cage does seem to have a bit of lateral (side to side) slop. not sure how much is acceptable? My existing freewheel is Alpha 13-30 looks to be in good shape. cables and housings are new from my LBS the housing are a Bontrager brand not sure if their comparable to the Jagwire brand? Please correct me if i'm wrong from the literature it appears the choices applicable to A.T.B's seem to be limited to just a few of the long cage variety? Also Not clear from the literature the difference between derailleur capacity say 34T and maximum # of teeth? Not sure if I stated this correctly. There's a bewildering plethora of Suntour models and stuff on ebay taking hours to familiarize my self . I'm obsessed with my quest for knowledge here, I'm really learning as I go hope you all can bear with me.

maddog34

30-13 = 17 teeth CHANGE/Range....

large Ft. ring tooth count - small ft. ring tooth count = X

17T + X = ?
Max teeth range (change) capacity... AKA in shop-speak: Wrap.

max freewheel size is 30T, in your case.
Long cage derailleurs have both a larger max tooth Change number and a larger max Freewheel size number.

unless you're set on a restoration as stock, i'd ship out the oddball suntour parts and install updated shimano indexing shifters, and a 7 speed freewheel.
alternative... get the der. hanger positioning verified, renew the cables/housings, and grab a "newish" 3040 off ebay, 'cuz the cyclone (long cage or not) won't play well with the suntour 3000 shifters, eh?

for the record.. i run cyclone on my 1983 Trek 930R road bike... it works great, friction shifting it with suntour bar-end shifters, on a 6 sp. freewheel.... i've had that bike since before it had wheels, so... yep, i'm partial to it

70sSanO

Since the other shifts are fine, I’m more inclined to place blame on the shifter and not the rear derailleur. I’m assuming the 1-2 shift is okay as well as the opposite 2nd to 3rd. Not sure if the cage lateral movement is a factor, since the other shifts are fine, I would discount that. Oddly enough it might even slightly mimic Shimano’s Centuron pulley, but that is more in jest.

If it is any consolation, I have a similar issue with a set of Shimano 6401 8 speed downtube shifters. Mine is 2nd to 3rd. The shifters are NOS, original boxed, so I am not too happy. I chalk it up to a sloppy detent in the mechanism. I’ve fiddled with slight cog spacing mods to trick it, but it hasn’t been foolproof as the mods can impact the 3rd to 2nd if not just right. By the time Shimano 8 speed came around I imagine downtube shifters were not viewed as much of a priority compared to STI shifters.

John

jzr756

Thanks maddog34, and thanks for the suggestion! Got me curious now...in changing up from a 6-7sp. freewheel is this accomplished via closer 7sp cog spacing and reduced chain width Or how does that work? Are we talking new currently available models/components? Can you go into some additional detail ? Sounds like a pretty nice viable solution.

maddog34

the chain width remains nearly identical... chains in that range are regularly marketed as "6-7-8 speed compatible"
the shift indexing takes care of the difference in Cog spacing.

the only limiting factor becomes the Chainstay and Dropout shaping... my trek is a close-fit Road Race bike,,, the room available prevents a simple swap... that clearance between the Dropout and the Small Cog on the freewheel is the Limiting factor...
A typical 7 sp. Freewheel is about 33 to 37mm thick(some have an outer collar ...a 6 sp. freewheel measures 31 to 33mm... measure from the tip of a tooth on the small cog outward to the Chainstay tube to checjk for clearance... you'll want at least 3-4 mm, since there has to be room for the chain too... the Chain hits the chainstay when i installed a 7 sp. onto my Trek.. i just swapped a 7 sp. onto my Santana Tandem this summer... it went on with zero changes, except for adjusting the derailleur and cable a tiny bit.

backside spacing is fairly consistent between a 6 and a 7 sp. freewheel, btw,,,

Kontact

All you have to do is move a slim spacer from NDS to DS and dish. It has nothing to do with the frame.