...

Shaft drive isn't popular on bicycles because the differentials which change the axis of applied torque, are thermodynamically inefficient. With a shaft drive bike you're eating up 5-10% more power than a chain or belt drive.

Belt drive with IGH or Pinion gearbox are more efficient and just as clean/maintenance-free, though you do have to replace the belt once in awhile (they last upwards of 15,000 miles).

...

The future may hold more shaft drive bicycles in store, particularly as more people get into commuter/utility cycling as a choice, not as a necessity.

I also moved to shaft drive motorcycle after a cross country trip on a chain drive and tired of lubing it and the mess it made. Run a Moto Guzzi and it has been wonderful for the last 15 years. Change the oil once a year and keep on motoring. On the bicycle I don't like IGH, so chain it is. Not too messy, really, and wheel removal/installation is much easier with less hassle. I do see shafties for bikes if the cost comes way, way down, but the IGH will prevent that from happening even if they figure out how to do a low cost shaft drive.

They would seem to be a great bike for gravel grinding.

Combine The % of IGH energy loss, and the added % from those 2 bevel gears , and live with it..

purists will find the exact numbers for you.

biggest issue I see is you cannot change the gear range up or down..

So, you just cope with the one it is , as is.

I've never seen one, but I would not call you an "idiot" for loving shaft drive bikes. You've got two versions, I think that's cool!

As for why they haven't caught on - there's probably 20 reasons but my guess is the only reason that matters is money. Sram probably has $5 in a $50 chain, and it's disposable.

...

Sincere request --keep us updated on how the drives wear as you put on the miles. 2000 clicks is well within what I would expect to get from one chain.

I haven't even seen one of these, but my biggest concern would be the possible difficulty in finding replacement parts, so I'm curious to know how bullet proof they really are over the many miles I would likely put on them.

Thanks for posting about this. I'm glad you are enjoying the bikes, and want to get your impression of how they hold up.

Wow, didn't know about shaft bicycles that would be awesome but out of space in the garage.

I also have a 96 Guzzi California and a 06 kawasaki concours love em both.

Very cool. You'd think shaft drive bikes would be more popular due to the massive government-sponsored marketing campaign...

Dig the "mag lev spoke" system too!

A chain drive isn't a big enough hassle for me on a bicycle to look at alternatives but it definitely was for motorcycles.

1968 BMW R60.. they look like this; not mine but you get a picture, this way.

You start with an insulting comment, then go through several reasons why shaft drives are inferior then say that that you think their future is bright. I found your note unconvincing.

Youre right: It's hard to make shaft drives light and compact. They are more costly (with two spiral-cut bevels, it's unlikely that they'll ever be relatively cheap). They do put a significant torque on the rear triangle that just isn't there with chain or belt drives. So a beefier rear triangle is needed. You mention 'modern "spiral" tooth pattern setup'. Spiral bevel gears have been around since at least the 1920s, and I think even back into the 1800s. The gear machines back then used clever geometrically appropriate hobs (gear cutters) to precisely "generate" the spiral gear tooth pattern precisely. What is modern about this?

It's true that enclosed shaft drives are enclosed and won't snag your trousers. As someone has said, shaft drive is an approach that surfaces every few years and never really catches on. With all of the disadvantages, and few advantages, why would people want these?

I read your points, and have to say they aren't compelling for me. But you commute, and you may weigh different aspects of cycling different than I do.

Keep pushing. Man's reach should exceed his grasp, or what's a heaven for? and all that.

let me know when shaft drive bicycles aren't dopey cruisers.

...

...

It's probably fair to say that the bike industry has explored shaft drive for a hundred years or more. I'd love to try one! I get that shaft drive could represent a fair trade off for certain use cases like urban commuting, for example. I also understand that shaft drive is an expensive bet for a brand to risk making. It's fun just knowing there are a couple brands still producing shaft drive bikes.

...

The Ceramic Speed looks very interesting, but they certainly make grandiose claims without showing any proof they have a working bike with such efficiencies.

They claim to have been track testing, but I find it very suspicious that there's no video of this, and none of their mock-ups have shown an actually working shift mechanism.

As far as materials technology advances leading to greater efficiencies and easier maintenance, there's no reason in principle that won't apply to chain-drive as well--chains may look very different in 20 years.

Technologies seem to develop faster when there are competing lines of technologies, so I'm rooting for shaft drive to advance, but I remain skeptical that it will be anything other than a niche for quite a while. People with poor wrenching skills, like myself, will likely steer clear of it for a while because we wouldn't know how to deal with problems, and think it would likely be a very expensive prospect to find someone who does. .

I predict that the chain drive will advance with technology advances in the cogs and the chains themselves. If there were "worthy" advances in bicycle drive systems we would have adopted them by now.

Ok, so I'll point out that "Tell us something we don't know" that is pretty unambiguously insulting (belittling, patronizing) in English. I bear no ill will, just something that might be useful to you in the future. I hope so.

To some extent. Bevel gears are certainly complex. Even generating the proper tooth form on spur gears is exacting work. But the spurs on a straight bevel are tapered, and any plane tangent to a tooth surface intersects a common point. To this end, special bevel gear tooth cutters were used. Once set up, they generated the tooth profile nicely.
Spiral bevel gears were even more complex. Complex hobs (gear cutters) were used. Once set up, the gears could be mass-produced (think differential gears in cars, some of which were hypoid*!).

The pics you shared of the various shaft drives were great. Really enjoyed them, much appreciated.

When you get to a certain age, there's a tendency to thing "been there, done that" and to lose some enthusiasm for novel (or in this case, kind of novel) things. Sorry if my note was not as supportive of investigating alternate ways of thinking about bikes as perhaps it should have been. Good luck with your enthusiasm! Good riding, too.

I appreciate the OP's enthusiasm, and the bikes look really nice, but I really can't see shaft drives having any advantage over good chain drives in similarly-purposed bikes using IGH. The chain problems have (almost) all been solved for a long time with fully-enclosed chain cases, and the last one--changing tires/tubes--was recently solved by WorkCycles, with the "Escape Hatch" featured on some models. The whole left side dropout unbolts from the frame and wheel, leaving the right side with the chaincase and shift cable undisturbed while giving access to replace a tire or tube. Scroll down this page a little and you'll see it:

Bakfiets en Meer » Overview: WorkCycles Fr8 Transport Bikes

How easy is it to change the rear tire on one of yours? I can't tell from the pictures, but it seems to me you may have to loosen the shaft assembly at the front in order to get the wheel out of the frame. Or does it simply slide straight out? Even then, you still have to disconnect the shift cable.

Again, for the same kinds of bikes, I think the economic advantage still goes to chain, especially in manufacturing cost; anybody with a couple of punch-presses can make good chain, but the machinery for cutting and heat-treating those gear teeth has to be a lot more of a capital investment. And with a straight chainline, the chain (and chainring and cog) can be wider, spreading the stress over a wider area to reduce wear. Also, the straight-line chain doesn't incur wear from bending sideways or having its sideplates grinding against the sides of cogs and chainwheels and derailleur gates. Altogether, I'm really surprised anybody's making shaft-drive bikes at all.

If I'm not mistaken, CeramicSpeed has openly admitted that they have yet to solve the problem of how to shift gears with their design; this has been discussed elsewhere. I doubt it can be done at all without an electronically-controlled servo, and maybe a heavy one at that--powered by a largish battery.

I don't mean to shoot down the idea; I just don't think it's ever going to catch on in any big way.