Review of non-Hobie replacement Mirage drive (GT) sprockets

I ordered these non-Hobie GT drive sprockets:

https://www.amazon.com/gp/product/B0FBRHN12D/?th=1

The pair cost $60, which is not a whole lot cheaper than the actual Hobie GT sprockets, which apparently list for $39 each:

https://westcoastsailing.net/mirage-drive-gt-threaded-sprocket/

However, like most Hobie replacement parts, the sprockets seem to be unavailable at present, so the non-Hobies were the only option.

The non-Hobie sprockets seem to be made of slightly different sort of plastic. Another weird quirk is that the bearings are slightly shorter (more than 1/2" as I recall) than in the real Hobie sprockets, but that did not strike me as a major issue.

I had installed these on a GT drive, and used them a couple of times without any problem. However, yesterday, the chain "slipped" before I even got out of the harbor. I circled back to the dock and managed to fix them, before heading out again. I spent most of the day babying the drive, as I was concerned that excessive pressure would cause it to slip again. It was OK, until I was coming into the harbor, and it slipped again, as shown in the picture. Note that in this picture, I'm holding the crank arms even, and both fins should be pointing straight down, but neither one is so, in fact, both chains slipped.

I use nylon bearing instead of the provide delrin bearings, and I did not have an idler cable (or even bungee cord) installed, but I've used this exact setup a bazillion times with standard Hobie sprockets and never had any problem.

My guess is that the plastic used in these knock-off sprockets has slightly more flex. In addition, the center tooth in the Hobie sprockets is slightly larger, which semi-locks the chain in place, but that is not the case with these fake Hobie sprockets. Together, these (and possibly other...) factors allow the chain to slip.

Of course, this could almost certainly be prevented by tightening the chains, but it seems to me that they would have to be tightened to the point where you would lose a significant degree of pedaling efficiency.

The bottom line? Don't get these unless you have not other choice!

Appreciate the review. I have two well worn Hobie drives but just keep pedaling and wait for breakage before doing an overhaul. If parts at a reasonable price were available I'd probably replace what's worn but it looks like Hobie has the better replacement stuff except, perhaps, for drive cable/chain.

A while back I remember seeing some brass gears for Hobie drives.  I think brass gears with your full-chain drive would make a Hobie drive about as close to bomb proof as possible.

Is there a standard tension for the chains? I've seen/used a handful of various drives, Hobie and knock offs, and found that they vary significantly. Seems difficult to torque to a specific value, and it might back itself off anyway.

A while back I remember seeing some brass gears for Hobie drives.  I think brass gears with your full-chain drive would make a Hobie drive about as close to bomb proof as possible.

Is there a standard tension for the chains? I've seen/used a handful of various drives, Hobie and knock offs, and found that they vary significantly. Seems difficult to torque to a specific value, and it might back itself off anyway.

The same people who sell this knock-off (and substandard, IMHO) sprocket also sell a stainless version, but those are $200 for a pair (with or without masts). It would be cool to test them out, but that's out of my price range, and I would not be surprised if there is some squeaking due to the metal-on-metal.

As for chain torque... Nothing specific, but there is an interesting discussion of the Hobie forum (can't seem to find it at the moment...), where the consensus is that you want them somewhat loose for maximum efficiency (basically, if you try to pinch the 2 cables together, there should be some movement), and I also find that having just a little bit of slack at the top of the pedal stroke keeps my knees happier.

I carry a spare mirage drive with my full-chains, but that only has ST fins (slightly fatter than standard fins, but not as long as turbo), which is the only reason I didn't switch to that drive yesterday. I'd have had trouble making forward progress against the afternoon wind without turbo fins (only really necessary to undo snags).

If anyone needs the hobie sprockets mariner sails has them in stock but you need to buy the sprocket and regular mast.

https://www.mariner-sails.com/

If anyone needs the hobie sprockets mariner sails has them in stock but you need to buy the sprocket and regular mast.

https://www.mariner-sails.com/

It looks like it's only available with the standard masts, not turbo. That's $145 for the pair, while individually, the sprockets are only $39, which seems like a lot for a couple of useless masts. At that price, I'd probably take a chance on stainless sprockets...

If anyone needs the hobie sprockets mariner sails has them in stock but you need to buy the sprocket and regular mast.

https://www.mariner-sails.com/

It looks like it's only available with the standard masts, not turbo. That's $145 for the pair, while individually, the sprockets are only $39, which seems like a lot for a couple of useless masts. At that price, I'd probably take a chance on stainless sprockets...

I wouldn't mind splitting the cost with anyone to keep whatever you don't need for spare parts just let me know