Tell me about freewheel cog spacing vs. chain width.

I finally got the freewheel off the rear wheel of the tandem I'm rebuilding. It's a Maeda 6-speed, one of those narrow-spaced freewheels only slightly wider than a normal 5-speed.

My recollection from back in the early 80's (until recently the last time I paid serious attention to bike parts) is that when 6- and 7-speeds first came out "they" offered narrow freewheels to allow 6-speed upgrades on 5-speed (120mm) bikes, and 7-speed upgrades on 6-speed (126mm) bikes. But these narrow freewheels required a special chain, perhaps called Ultra or some such marketing nonsense. Both the '82 and '83 Peugeot catalogs listed a Normandy 5-speed for the TH8, so the 6-speed upgrade would seem to be one of these narrow varieties.

Now, I could simply continue to use this narrow 6-speed (even though I'd rather change the gearing). But for yucks I checked it against the new PC-870 chain on my Raleigh. It looks like the chain is too wide for those cog spacings.

As an experiment I tried mounting my Raleigh's the new 6-speed (126mm) Shimano freewheel on the tandem hub, then putting it on the bike. It looks like the freewheel will be too close to the stays for shifting onto the small sprocket.

So I have two options, find a narrow chain or go to a 5-speed freewheel. I like the looks and so far am impressed by the shifting performance of the PC-870. So I'll probably go with a new IRD 5-speed, probably the 13-28, or 13-32 if I felt like stretching the RD to its limits.

So here's the point. Do I recall the freewheel/chain width issue correctly? Would any of you recommend a narrow chain? I would suspect a narrow chain might wear faster. Also since I'll be needing to create custom-length chains for both sides, it might be more cost-effective to chop several standard chains whose left and right sides can be mixed-and-matched.

As always, thank!

I've used a SRAM PC-830 chain with a Narrow 6 speed Suntour freewheel in a 120mm spaced drop and had no issues.

For my 126mm spaced rear hubs I use 7 speed Maillard 700 FWs in combination with Sedis SL and Sedis/Sachs narrow chains. The narrower Sedis chains works great with the narrow spaced 7 speed FWs. Although I also tried to use the narrow chains on regular spaced 6 speed FWs but they were noisy and shifted a bit sloppy and slow. So narrow spaced FWs works best together with narrow chains.

Chombi

Jim,

I've done the same as Capecodder. On my Schwinn Tandem I'm running a Suntour 6 speed ultra using barend shifters, with no problems. IIRC, I'm using Nashbar 8 speed chains which are KMC. I ordered 3 and spliced two together for the timing chain.

Let me know if you need help building the freewheel with the range you desire.

Back in the day, the recommended chain for Suntour New Winner Pro Ultra 6 and 7 freewheels (that fit into spacing for 5- and 6-speed respectively) was a Sedisport chain. That concern has morphed into SRAM. I used this combination for many years, but when I wanted to replace the chain, I got a SRAM PC-58 (now renamed PC-870, I think). The PC chains are nice because they have a "super link" that makes removal and cleaning much easier. Most people report no problem with this combination, and it shifts just fine for me, however when pedaling inj the middle gears on my 7-speed Ultra, I notice a slight "hitch" every few revolutions, just barely sensible but annoying, that I believe is the removable link catching on the uphill sprocket from the one I'm using. I replaced the FW with a 6-speed non-Ultra, and the "problem" disappeared. YMMV. BTW, Sedisport chains are still available on eBay NOS.

As to using a standard 6-speed FW, you would need to respace the rear wheel to 125 or 126 spacing from the 5-apeed's 120. That would mean re-dishing the rear wheel (since you'd add all 6 mm of spacers to the right-hand side of the axle), but that's easy enough. It's not necessary to re-set the spacing on the frame; just spread the dropouts apart by hand when inserting the wheel.