Shimano Nexus 8: where to find a "CJ-8S20 Cassette Joint Unit for belt drive system"?

I'm looking for Shimano spare parts for the Nexus 8 SG-C6001-8R:

- Y73E98020 CJ-8S20 Cassette Joint Unit for Belt Drive System - Y73E98030 CJ-8S20 Cassette Joint for Belt Drive System

I’ve searched a lot but haven’t found them. If you know a site that sells these parts, thanks in advance!

My favorite site for Shimano parts, http://bicikli.de, unfortunately doesn’t have them in stock.

Well, actually, Gates support got back to me saying that the version for chain transmission of the CJ-8S20 is compatible, so no need for it.

It depends on the bike’s frame setup, since the cassette joint arm is offset by a few millimeters between the two versions—one for chain and one for belt.

It’s hard to find because 1) these bikes are rare compared to overall production, and 2) the users who actually need this part are even rarer.

CJ-8S20BD Cassette Joint for Belt drive system Y73E98030 7.95 € https://www.veloruf.com/n/shimanospares.html?id=50879754&art=140658028&lan=n5932262947.4719853816

If you can’t find the belt-drive version, you can use a strap to pull the arm far enough outward so the cable doesn’t rub against the belt sprocket.

Thanks! :)

I just ordered it from this German site. We’ll see if the part arrives and if it actually fixes this minor issue I’ve been living with for two or three years.

If you don’t pull the arm outward, the cable rubs against the belt sprocket teeth and frays.

As I mentioned in Gates' response, the chain version is compatible, and I've tested it. It works. So, I don’t understand why you’re having an issue. Unless we’re not talking about the same thing.

But thanks for the site—my previous supplier for the narrower belt-compatible cover no longer exists.

In September 2024, I bought a Sava Z1 20-inch, 9-speed, single-chainring, fully equipped carbon bike. I wanted the double-chainring version, but it was sold out.

I set it up just like my Tilt 9, with the same Pletscher rack, seatpost suspension, Brooks B17 saddle, and MKS removable pedals. I had to add a B&M dynamo with front and rear lights.

All in all, the bike weighs 13 kg instead of the Tilt 9’s 18 kg. Saving 5 kg makes a big difference on SNCF station stairs and the like.

Now, the only thing left to solve is that the bike was delivered (unbelievably) without a locking mechanism in the folded position! I bought a magnet system, but the parts don’t align perfectly, and the mounting clamps are too flexible. Because of this, the bike comes apart when you push it on two wheels like a shopping cart. I had the idea to repurpose dynamo mounts—I’ve ordered some. We’ll see how it goes.

I’m not a fan of this trend of single chainrings with 9 or even 10 cogs. The chain is thin and really twists when you shift to the largest cogs. I’ve adjusted the limit screws to avoid using the biggest cog. Eventually, I’ll swap it out for a setup with a chainring, 8 cogs, and a short-cage derailleur. An 8-speed chain is more durable.

That said, I love this bike—I’ve regained an efficient pedaling position like on my hybrid bike.

As Gates' response mentioned, the chain version is compatible and I've tested it. It works. So, I don’t understand why you’re having an issue. Unless we’re not talking about the same thing.

It might depend on the frames, but on mine, the cassette joint arm needs to be slightly more offset to prevent the Nexus cable from rubbing against the belt sprocket teeth. You can avoid having to bend it outward with a strap. If Shimano offers two versions (chain and belt), there must be a reason :-p

I just bought, in September 2024, a Sava Z1 20-inch with 9 sprockets, 1 chainring, fully equipped, in carbon. I wanted the double chainring version, but there weren’t any left. […] Today, the only thing left to solve is that the bike was delivered (unbelievable) without a locking solution in the folded position! […] This trend of single chainrings with 9 or even 10 sprockets—I don’t get it. The chain is thin and really twists when you use the largest sprockets. I adjusted the limit screws to avoid using the largest sprocket. Eventually, I’ll change it for a setup with a chainring + 8 sprockets + short-cage derailleur. A chain for 8 sprockets is more durable.

Personally, I’d: - use a simple strap to keep the front wheel pressed against the bike after folding - install a clamp + block compatible with Brompton bags - try the Sturmey-Archer CS-RK3 hub instead of a double chainring: marginally (if not) heavier, with the advantage of being able to start in a lower gear if you’ve stopped in too high a gear.

>> I’d use a simple strap to keep the front wheel pressed against the bike after folding

I want to be able to push my folded bike on its two wheels like a trolley, so fixing the front wheel isn’t the solution. I tried strapping the fork, but once folded, nothing lines up face-to-face. Gave up on that.

>> I’d install a clamp + block compatible with Brompton bags at the front

Yeah, I considered this kind of solution to carry my duffel bag (6 kg) with camping gear (tent + sleeping bag) and balance the load. But I ended up doing what I know how to do: a rear rack for a large wheel, like on my Tilt.

>> I’d try the Sturmey-Archer CS-RK3 hub instead of a double chainring: marginally, if not, no heavier, with the advantage of being able to start in a low gear if you’ve stopped in too high a gear.

Yeah, I really like internal gear hubs, but for now, I’ll stick with my nine-speed cassette reduced to eight gears and the original single chainring. Plus, three gears are way too few. I switched from a 7-speed hub to an 8-speed because I wasn’t happy with the 7-speed—so three gears would be a step back... And then, finding someone in Bordeaux who can build a wheel with spokes is a nightmare. I found someone who built me a solid wheel with my rim and my Nexus 8 hub. He did it off the books at his place for 80 € back then. Not sure I’d find him again five years later.

Thanks for all the info

Not three speeds: 3x8-10

And since there are always duplicates/gears that are very close, it gives ~half the unique speeds, so 12-15 speeds

With a 40-tooth chainring: https://www.sheldonbrown.com/gear-calc.html

For wheel truing, people make a big deal out of it, but even without knowing much, I’ve done some that turned out just fine. It’s even easier with a disc brake, since the wheel can handle a bit of wobble/jump.

All you need to do is: 1) screw each spoke until the screwdriver slips, then 2) give each one three full turns with the wrench, 3) check the tension of the master spoke with a cheap tensiometer, adjust if needed (counting the number of turns), then 4) apply the same to the other spokes. Finish by simply tapping the master spoke with the wrench to hear its tension, and tighten the others until they sound the same.

Ah, okay, I didn’t realize there was a combo with a 3-speed hub + 8 cogs. I wasn’t aware that existed.

At this point, it's the only hybrid hub left, since SRAM stopped making speed hubs and thus discontinued the DualDrive.

Solution to consider for a bike not designed for a multi-chainring setup.

Ah, right, that reminded me of the Dual Drive I’d completely forgotten about.