I would say the biggest point with a gearbox is moving the weight, obviously a cassette is very central to the wheel but people spend a lot of money to reduce wheel weight. Also suspension may improve if the frame design keeps a fixed chain length and high pivot will suddenly become the norm.

It’s like their engineers spend 4 years of absolute dedication making a great bit of kit, but do it from scratch and forget every lesson they learnt last time. Either they bend as soon as you look at them, the pivots go sloppy, the jockey wheel seizes, or something else is wrong.

Can’t remember where I read it (wish i could claim credit) but the best description I read was SRAM is essentially just a continual beta test…

For those who’ve never broken a rear mech……

Maybe you haven’t, but I’d be careful about trying to extrapolate that experience to others.

This is fair comment, but if like me your into the 5th year on a mech, hub gears and gearboxes make no sense whatsoever. But if people can find a system that suits them it’s all good.

In 30 odd years of riding off road, in all conditions and in locations all over the world, I’ve never bent or broken a mech. The worst I’ve ever managed is a few scraps on the body. I’ve replaced more jockey wheels than mechs, and I would say my experience is in no way unique amongst the folk I’ve ridden with either. IME they aren’t fragile in a way that makes me want to look for an alternative.

This.
25 years of riding on and off road and I’ve never trashed a mech but have trashed a mech hanger which was doing its job due to me putting a back wheel in misaligned.
I’ve worn out a few mechs mind you, the last one cost £25 and 15 minutes in the work stand to replace, lasted about 2k miles on my commuter bike.
And for those reasons I will stick with derailleurs all day long thanks.

Okay, as someone who has ran both a hubgear and a dynamo for over 8 years and 30000+km, I’ll weigh in.

I’ve ran a Alfine 11 in one guise or another since early 2012 and a series of SA hubs long before that.

1. In mechanical form (cables) they are no more reliable than a derailleur, cable tension is critical and more frequent oil changes make-for better performance.

2. They are HEAVY! My alfine 11 gives up over 1100g to a 1×11 XTR drivetrain and its all at the rear. You can feel it, all the time.

3. They are draggy, and you can definitely feel it. This is especially true for the first 1000 miles after servicing.

4. They’re not cheap. Alfine 11, motor, shifter, battery ~ £600. XTR cassette, shifter, mech, hub, £450. You can go a whole lot cheaper and still be significantly lighter.

5. If they get damaged (and they do because they’re easy to abuse) the repair costs can be very high, sometimes requiring the hub to be replaced.

As a test, I’ve just bought a Di2 XTR rear mech and will be swapping my Alfine 11 Di2 and Exposure Revo for a set of CKs and 1*11 Di2 for this winter. That’ll be about 1500-2000km of commuting in shit weather on basically the same bike but with mechs instead of hub gears.

My suspicion is that becase of di2, the bike will behave exactly the same, but will feel much lighter and will require more maintenance.

Bit of feedback here. So, it was a little more complicated than just fitting a Di2 Rear mech. It also needed a new display and battery in order to work with both the Alfine and XTR M9150 RD. Also, I had to swap cranksets as the chainline for the Alfine is totally wrong for 1*.

Anyway – I’ve now been riding the derailleur equipped bike for over a week and about 200km. It’s so much lighter – almost 1.2kg, the bike is so much more lively that I almost fell off the thing when I went to pedal out of the saddle for the first time. The bike also maintains speed much better than the Alfine, even when the Alfine is in gear 5-6 (1:1) and so I have to pedal less. On a 54km round trip commute, I’m about 2-3kph faster with the derailleur than the hub gear, I also have less fear of changing gear (You have to back off on the Alfine), but I do miss being also to shift gear while stationary – it’s surprisingly handy on a commute.

I’m going to run it like this until Christmas and then change back for January and see how it feels going the other way.

On a 54km round trip commute, I’m about 2-3kph faster with the derailleur than the hub gear,

Blimey. Not an insignificant amount, that!

Be interesting to see how it goes once you swap back.

Umm…

https://youtu.be/XDqgupdsCJE

Skip to 18:00 if you don’t want to hear about the new Deviate Highlander, their new HSP 140mm 29er with a conventional gear setup

I think McTrail rider had got used to the mech-free benefits of the Deviate Guide.

In certain applications yes… Starling Spur moves the idea on a few notches.

https://www.instagram.com/p/BxB9SYHA4yi/?igshid=1dfm83n6r8wpz

high pivot rear axle path, no chain growth, perfect chainline all the time, no mech to hit off and a v light/strong rear wheel allowing far superior suspension performance. And silent. If you have every ridden a full sus dh without a chain you will know how good the bike suddenly feels. This rides like that all the time!!

That Effigear is a lovely mechanical solution but all those gears meshed all the time?

Another vote for “Gearboxes sound great, but I don’t actually break derailleurs”.

That Effigear is a lovely mechanical solution but all those gears meshed all the time?

It’s how motorbike gearboxes have worked for many, many years.

Yes, but 745.7 Watts are equal to ONE HORSEPOWER

And I don’t have 745 Watts. So losses are A Thing for bicycles in a way motorbikes don’t need to worry about.

Edit: the effigear *does* look pretty, though. I agree there.

That Effigear is a lovely mechanical solution but all those gears meshed all the time?

But only one is coupled to the input shaft at any one point (otherwise it would only have a single ratio) – I’ve probably missed your point though?

It does look like a good, relatively simple (read serviceable) solution though.

Its a “constant mesh” gearbox I think. So all gears are meshed at all times but only the gear pair you are using are fixed on the shafts – the rest are freely rotating. so you are turning every pair of gears all the time. They will be under no load so drag will be small but it will still be there

Ah yes, I see your point – if the sprockets are fixed on the output shaft they will spin the unused input gears (it would be possible, I guess, to only couple the selected sproket on the output shaft too, but more mechanically complicated).

FWIW the situation is similar in a derailleur system in that you spin all the chainrings and the whole cassette all of the time.

I really wish they would come up with something better.
Replacing a chain every 500 miles then replacing the entire group set after 2000 miles is pathetic considering the 0.2 horsepower I’m putting through it.

For E Bike’s they only last half that and cost twice as much! 4X more maintenance, or is that 6 to 8X more in time terms given the higher speeds ?!!

The benefits of gearboxes are good, lower unsprung weight, durability, maintenance etc.

The biggest thing holding them back, is lack of demand.

Imagine a buyer speccing 2021 bikes at a big manufacturer, they have a choice between a frame than can be used across multiple models, with various spec of drive train from multiple manufacturers (for which they probably get a massive discount), priced from £2000 to £6000 (for a typical FS bike), and that is 99% guaranteed to sell well.

Or, they could build a brand new frame which will only take a single, specific drive train from a single manufacturer, which due to the cost can only be specced on a £5000 bike, which might sell well, but might not.

That’s a big old risk. It needs one of the big players (shimano or sram) to build one, but they’ll still be low in demand, due to the frames needing to built specifically for them, and the cost.

Meanwhile the derailleur continues to be refined and refined with smoother shifting, more range etc. And for the vast majority of people, the durability isn’t an issue.

If gearboxes take off, I reckon it’ll be start with an ebike specific one. As the motors get smaller, there’ll be more space free for a gearbox, maybe attached directly to the output of the motor in some way.

They will be under no load so drag will be small but it will still be there

This

FWIW the situation is similar in a derailleur system in that you spin all the chainrings and the whole cassette all of the time.

Well no. When gears mesh, the teeth slide over each other as each tooth engages then disengages. This is what causes the drag. The extra sprockets on a derailleur system are just spinning in air not touching anything. As TJ says the drag will be small but you’re multiplying it by however many cogs there are. It’s a lovely solution but I think it’s going to be a bit draggy. This may not matter to you, of course.

Replacing a chain every 500 miles then replacing the entire group set after 2000 miles

Putoline. Seriously. Give it a try. I used to hate grinding my drivetrain away on wet rides, but there’s no grinding with Putoline. And you don’t have to clean it. One of the best £20s I ever spent.

I suspect e-Bikes will have a big impact on this matter in the future. You’ve already got a big, heavy, integrated into there in the bb area, so not a big leap to imagine gearbox integration.

You could have ebike and gearbox versions of the same frame – with a big SwaT box where the battery would be.

Own opinion. I rode the Pinion based Zerode. Didn’t like it, the clicky noise, the spongey feeling of the drive train. I got over the gripshift fairly easily.

If I wanted a hub gear bike, I’d got SA, with small chainring on a hardtail. Use for winter and out with the family rides. I’d definitely want a direct drive ratio. 3 speed single speed.