ffk27

Hello, I'm new on this forum and i like working on old road bikes.

A few months ago I was working on an old Batavus Course from the 80's with a rare 6-speed helicomatic freewheel cassette which I never seen in my life before. The bike was in terrible shape and the chain was ofcourse also worn out so I replaced it with a cheap KMC 8-speed one. After I replaced the chain, the chain would, while shifting, sometimes not fall into the cog properly and then slip over it. When it once was settled, it rode perfect with no slipping at all.

What I noticed on this cassette is that the cogs are really fat in width (2mm) while other 6-speed cassettes I measured where more like 1,7mm. Also the spacing seems less.

Do I need a special chain for this cassette? I noticed that the most new 8-speed chains have wider side plates. In another thread on this forum someone suggested a SRAM 830 or an Sedisport chain.

I will attach a picture so you can see what I mean. Thanks in advance.

P.s. it seems I can't upload pictures as a new user so here is a link imgurdotcom/a/m7wm9O8

daverup 

You need 10 posts over 2 days to gain the ability to link or include pics.
Your gallery is working and you did upload a couple of pics, here is a link,
https://www.bikeforums.net/g/album/33167253

daverup 

I've used the SRAM 8 speed chains on a couple of helicomatic freewheels. The gears are different than the more common Shimano or Suntour clusters, and may not engage as smoothly. The teeth of the helicomatic gears are not beveled or ramped like most others. I've never used a KMC chain on these, so I can't tell you whether or not that is an issue.
You will probably hear others advice on the need to change out these hubs for better designed models. The earlier helicomatic hubs have a long history of bearing failures, which might be attributed to the small bearings in the rear hubs. They also don't do a good job of keeping dust out of the bearings which contributes to problems. If you decide to keep them, I'd make sure you rebuild them after a thorough cleaning. Inspect the cups and cones for signs of bearing failure and use new grade 25 or better replacement balls.

Helicomatic



Shimano cassette

sd5782 

As mentioned earlier, you better check your axle cones before you go too far. I have one that shifts quite nicely on a 1983 Peugeot. I will look at it sometime, but I believe I put a Shimano UG chain on it a few years ago when I cleaned it up.

Edit; I was mistaken, and my nice shifting heliocomatic is using the stock Sedis chain shifting the stock six speed rear. The Sedis is the flat side plate style like older chains with the slightly protruding pins. Width is around 6.9mm across the plates and 7.4mm across the pins. Others may chime in about modern chains having a bit more side flex than these older style ones.

pastorbobnlnh 

I have experience servicing Helicomatic freewheels, but I've never actually ridden a bike equipped with one. I do have a few Helicomatic freewheels available for purchase and a fair supply of replacement sprockets.

With that said, I'd try using a better 9-speed SRAM or KMC chain, after cleaning the sprockets, derailleur jockey pulley/wheels, and chainrings. You don't mention if the shifting challenges are across all the sprockets or only on certain ones. If only on certain ones, there's a good chance the sprockets are worn and need replacing. In your two pictures of the freewheel, I see significant grime, grit, etc., and wear on the smallest sprocket.

ffk27

Thank you for your reply. I'm not sure if I have an early model helicomatic. I uploaded a picture of the bike in my gallery. This is the first Batavus bike I worked on which didn't have a serial number at all so I don't know the production date, but I think it's early 80's. As far as I remember, I did clean the bearing balls and cups and did not see anything unusual.

ffk27

As I remembered, this happend in every gear but I'm not sure, because it's almost 4 months ago since I worked on it. I gave it to my sister but currently see has a broken brake cable and doesn't ride it anymore. I will later come back to this. Also I will ask her to clean the cassette with degreaser and then send a clear picture of it so you guys can maybe determinate if it's worn out.

JohnDThompson 

FWIW, Trek used a lot of Helicomatic hubs back in the 80s, and we installed Sedissport chains on them. Sachs bought out Sedis many years ago; one of their 7 or 8-speed chains ought to work on the Helicomatic cluster.

madpogue 

I wouldn't call a 6-speed Helicomatic "rare"; actually, all the Helicos I've come across except 1 (a 5-speed) have been 6-speed. The Treks all had Sedisport chains as mentioned. I replaced the worn Sedisport on my "frequent rider" (Ruby) with a KMC Z-chain. I forget the model designation, but I see "R6" on the outer plates. This one[/url is different (mine does not have those windows), but I reckon it would suffice for any six-speed friction ops.

madpogue 

I wouldn't call a 6-speed Helicomatic "rare"; actually, all the Helicos I've come across except 1 (a 5-speed) have been 6-speed. The Treks all had Sedisport chains as mentioned. I replaced the worn Sedisport on my "frequent rider" (Ruby) with a KMC Z-chain. I forget the model designation, but I see "R6" on the outer plates. This one is different (mine does not have those windows), but I reckon it would suffice for any six-speed friction ops.

Arrowana

See those tiny little grooves on the top of the cog teeth? The chain is getting stuck on those. Many French cogs have this design, and they are all at risk of this happening. Throwing a modern 8-speed chain makes the problem even worse. Finding a chain that has the same width as the original will make it less likely to happen, but will not eliminate the problem. Your best course of action here is to replace the rear wheel with something that uses a standard freewheel or cassette.

oneclick 

The type of chain most reluctant to get caught in those grooves is one withOUT beveled side-plates.

dddd

^^This kind of jibes with my own experience trying many (including 9s) chains on my Peugeot PH501.

The Sedisport chain is the correct one and I found none that worked quite as well.

The center-to-center cog spacing of nearly all Helicomatic freewheels is narrow, meaning that the Sedisport chain is also the oldest one to be found that will be narrow enough.

I took one apart and added bevels that mimicked Uniglide cog tooth features, but to little effect.

I ran one indexed on a Suntour Accu-7 equipped Cannondale R300, which did index effectively through six gears, but with too many "false-neutral" events for my liking.

EDIT: I seemed to only encounter slippage when shifting toward larger cogs, never in the other direction, and why I tried adding Uniglide-style "twist" bevels to the tips of the teeth.

A woman rider once almost fell off her bike when she was riding close behind while I suffered gear slippage and lost all drive while shifting for a steepening grade.
After that occurrence, I replaced the Peugeot's rear wheel with a similar but Shimano freewheel-equipped wheel that I had sitting around, and the bike's Huret-controlled shifting is now quite excellent.

ffk27

Thanks for all the replies. I fisted posted this question on R-edit but got zero replies on this question. I have another hard question which one of you could maybe answer, but I will make another thread for this.
A Sedisport chain would be ideal but those are hard to get in the Netherlands and buying on from eBay and shipping it to the Netherlands cost more then the bike itself. To bad I already thrown the old chain in the trash.
​​​​​​I will try a SRAM 830 first.