Bicycle Mechanics - Suntour ARX GT Index Shifters Possible?

Hi All,

I recently picked up a 1985 Schwinn Le Tour with Suntour ARX GT components. The rear derailleur is a 6 speed and has friction downtube shifters. Is it possible to add 6 speed Suntour Accushift downtube shifters to be able to have the index capability, or am I SOL?

I have received conflicting information, because some sites say that the rear derailleur is not index compatible, whereas one site stated it was compatible. I thought the index function is all in the shifter and not in the derailleur itself? Thanks for your help.

I don't know one way or the other but I think I can explain why some derailleurs can't index properly. When the index shifter shifts, it pulls a tiny bit of cable. That cable pull is dependent on brand and speeds and is relative to how the cogs are spaced in the rear. So most shimano rear derailleurs are designed with a ratio of cable pull. They will move the pulleys in or out a certain amount of space dependent with the amount of cable pulled. So most Shimano derailleurs will move the pulleys a known amount with each shift.

Now maybe the Suntour derailleurs move the pulleys in or out a slightly different amount compared to Shimano derailleurs per index shift. That would mean that they wouldn't be able to index properly.

That is what I would imagine anyway.

If you want indexing and want it to work well, you might be able to go with some inexpensive Falcon/SunRace downtube shifters or get some Shimano compatible ones off eBay (around $15 a set), some new derailleur cables ($4/pr) some compression-less housing (about 1 ft) $3, a cheap Shimano index-compatible RD - like a TX31/35 - $15, a 6 spd HG freewheel, $12, and a 6-7 spd index HG compatible chain $5. That's roughly $55 + shipping/tax/handling - say $75/$80 plus some elbow grease. Note that the indexed downtube shifters are probably pretty bad. They might work for a few months but if you ride a lot or plan to, I'd go eBay and find some vintage Shimano 600EX downtube shifters. That's one way to do it and the rough cost if you can do the labour yourself.

However, I might suggest that you keep that Suntour drivetrain. I must have put 20,000+ miles on that kind of drivetrain during my sophomore - senior years in college riding a Bridgestone 300 and 400 and it was more than adequate for the hills of Berkeley. Keeping the drivetrain clean and lubed may be all that's needed to keep that bike going very well for years and years.

Before doing anything with the shifters, try putting a ramped freewheel on the rear wheel. I run friction shifters with ramped freewheels (i.e., the kind used for modern indexed systems) and they work fine. You may be able to upgrade to a 7-speed freewheel while you're at it. I did precisely that on my Raleigh Super Course, and it shifts fine. I did, however, eventually put a Cyclone II rear derailleur on the bike (I had it laying around) but it shifted fine with the aRX derailleur. You won't quite get to indexed shifting but you'll get pretty close. You may even find that you can get indexed shifters to work. If not, you may have to get a compatible set of shifters and RD.

Before doing anything with the shifters, try putting a ramped freewheel on the rear wheel. I run friction shifters with ramped freewheels (i.e., the kind used for modern indexed systems) and they work fine. You may be able to upgrade to a 7-speed freewheel while you're at it. I did precisely that on my Raleigh Super Course, and it shifts fine. I did, however, eventually put a Cyclone II rear derailleur on the bike (I had it laying around) but it shifted fine with the aRX derailleur. You won't quite get to indexed shifting but you'll get pretty close. You may even find that you can get indexed shifters to work. If not, you may have to get a compatible set of shifters and RD.

I am running friction shifting with an 8-speed SRAM hyperglide (Shimano) compatible cassette and I am shocked at how smooth the shifting is. I thought I wanted indexed shifting but changed my mind after running the Ultegra 8-speed bar-ends in friction mode (using Paul Thumbies on a Nitto Nordeast handlebar).

Before doing anything with the shifters, try putting a ramped freewheel on the rear wheel. I run friction shifters with ramped freewheels (i.e., the kind used for modern indexed systems) and they work fine. You may be able to upgrade to a 7-speed freewheel while you're at it. I did precisely that on my Raleigh Super Course, and it shifts fine. I did, however, eventually put a Cyclone II rear derailleur on the bike (I had it laying around) but it shifted fine with the aRX derailleur. You won't quite get to indexed shifting but you'll get pretty close. You may even find that you can get indexed shifters to work. If not, you may have to get a compatible set of shifters and RD.

I would like to thank everyone for their advice. Doohickie, which freewheel did you end up using?

Also, what is the difference between ramped vs. non-ramped? Are ramped just made for index shifting? In addition, which brand/model 6 speed freewheel would you recommend for my current setup?

Older freewheels from the friction days consisted of flat cogs. Ramped freewheels have features machined or stamped into the side of the cogs that help carry the chain from one gear to the next in a very smooth transition, as if it were going up a ramp (thus "ramped freewheel"). I used this one (http://www.amazon.com/gp/product/B003RLE9X8/ref=pd_rate_rs). I didn't want a huge range because I wanted to use the Cyclone II derailleur I had, and it has a short cage. The aRX I have has a longer cage, so something like this (http://www.amazon.com/gp/product/B001IORDH0/ref=pd_rate_ft) would work okay with that.

If you look closely (maybe blow it up a little) on this pictures of the Shimano freewheel I linked to, you can see the ramps in the side of the gears. They look like little raised lips here and there:

http://ecx.images-amazon.com/images/I/41ilkb2NpKL._SS500_.jpg

Basically, as long as the difference in teeth between the largest and smallest gear on a new freewheel is less than the difference on your existing freewheel, it should work okay for you. A 6-speed freewheel should work for sure. A 7-speed actually uses the same total width, so that should work as well, but it might be a millimeter or two tighter. If things rub, you can just put a washer under the locknut on the drive side to provide a little more clearance. The pedantic experts will say you should re-dish your wheel to account for that slight offset from adding the washer, but you should be able to adjust your brakes enough that they should work fine without redishing.

Older freewheels from the friction days consisted of flat cogs. Ramped freewheels have features machined or stamped into the side of the cogs that help carry the chain from one gear to the next in a very smooth transition, as if it were going up a ramp (thus "ramped freewheel"). I used this one (http://www.amazon.com/gp/product/B003RLE9X8/ref=pd_rate_rs). I didn't want a huge range because I wanted to use the Cyclone II derailleur I had, and it has a short cage. The aRX I have has a longer cage, so something like this (http://www.amazon.com/gp/product/B001IORDH0/ref=pd_rate_ft) would work okay with that.

If you look closely (maybe blow it up a little) on this pictures of the Shimano freewheel I linked to, you can see the ramps in the side of the gears. They look like little raised lips here and there:

http://ecx.images-amazon.com/images/I/41ilkb2NpKL._SS500_.jpg


Basically, as long as the difference in teeth between the largest and smallest gear on a new freewheel is less than the difference on your existing freewheel, it should work okay for you. A 6-speed freewheel should work for sure. A 7-speed actually uses the same total width, so that should work as well, but it might be a millimeter or two tighter. If things rub, you can just put a washer under the locknut on the drive side to provide a little more clearance. The pedantic experts will say you should re-dish your wheel to account for that slight offset from adding the washer, but you should be able to adjust your brakes enough that they should work fine without redishing.

Thanks for the advice and for taking the time to explain it to me. A noob like me really appreciates your help! :thumb:

I think I am going to stick to 6 speed and go with either of these two freewheels.

http://www.amazon.com/Shimano-6-Speed-Freewheel-14-28-Teeth/dp/B003EQ71QI/ref=sr_1_7?s=sporting-goods&ie=UTF8&qid=1340156198&sr=1-7&keywords=shimano+tourney+freewheel+14-28

http://www.amazon.com/Sunrace-Freewheel-14-28T-6-Speed-Silver/dp/B000AY9AGQ/ref=sr_1_2?s=sporting-goods&ie=UTF8&qid=1340156352&sr=1-2&keywords=sunrace+6+speed