noglider 

This video explains the ups and downs of gearboxes for bikes. It also showed some innovations that most of us don't know about.

Moe Zhoost

Fascinating video. Thanks for posting.

Kontact 

Just 5% power loss?

tcs

The gizmos are nifty, but downhill racing is a specialized niche within a niche in the bicycle world with very little application outside the discipline.

I tried to imagine a bicycle drivetrain for downhill touring. Yeah. You wouldn't need one.

Iride01 

I didn't watch... is that what the video said? If that much loss, then there'd have to be quite a few more pro's to offset that one con alone.

zandoval 

At 2.3Kg/5Lb That's GREAT!!!

Kontact 

5% for the internal gear box, 2% for the internal derailleur version.

I was always shocked when I worked on modern internal hub gearing. At the extremes of the gear range turning the crank felt like mixing pudding.

Of course, clutched RDs also feel like hell.

Shimagnolo

Trying to wrap my head around how the 1st & 2nd gen CVT boxes work, gives me a headache.
But I want one!

GamblerGORD53

Yah, I saw that too. Just proves how laughable they are compared to a 100% reliable and easy to use Rohloff14 or SA 3 is.
Defaileurs in a box. hahahahahaha

Pratt

Pinion makes a few.

Darth Lefty 

Pinion is the undisputed winner right now. The one Nicolai developed in the 00’s lost out, I suppose it was too DH specific. It had a high output shaft so it could do high pivot suspension without an idler.

I don’t think Shimano has a use for their parent right now. It shares too much real estate with STEPS.

elcruxio

The problem with rohloff is that it cannot handle torque. For a heavier rider the smallest permissible chainring/cog ratio means the gearing is going to be miserably high for steeper hills. A derailleur in a box would solve that as there's practically no way to overload such a system. Sadly a compact high range derailleur in a box doesn't exist.

tcs

Yep, but it's a bit of a big noise in a small room.

Folks have tried gearing at the bottom bracket for 125 years and have never made a big impact on the market.

icemilkcoffee 

I think the enclosed derailleur gear box is the right solution. With aero carbon frames, there is typically and increasingly a lot of room in that BB area. Same with the area between the BB and the front tire- that area needs to be filled in for aero. You can put the gearbox there. The point is to get the cassette cluster and the two derailleurs out of the air stream. The rear axle and Q-factor can also be narrower. A further evolution is for the entire final drive chain be enclosed in a carbon case. Now everything can be run in a wet bath and there is no mess on the outside.

Kontact 

2% power loss on a TT bike?

KerryIrons

Low mechanical efficiency and increased weight. What's not to like? People have been patenting bicycle gear boxes for about 130 years. They are ALWAYS heavier and experience significant efficiency problems. The more things change, the more they stay the same. Another mechanical engineer's wet dream.

icemilkcoffee 

I don't know how they measured that loss, but one advantage of the internal derailleur system is that the chain line is always inline and never crooked. On a conventional derailleur bike, The drivetrain loss probably varies greatly depending on which cassette cog you are on. Also- with the enclosed case the chain can be constantly oiled. That ought to offset some of that power loss.

Kontact 

There's a device that fixes the chainline in that box - that might be a loss. A liquid oil bath would definitely be a loss. So is having two chains.

elcyc

I miss my old Raleigh 3 speed with Sturmey-Archer “gearbox “. A bombproof tank of a transportation device.
Mine was similar to this:

GamblerGORD53

Check out Rei Bronson on YT. He is an outlier big tall guy, 310 lbs at least. He did a tour in SE Asia in 2010 on a LHT
He munched the pawls in 4 hubs and 3 rims in the first 3,000 miles. One was a 40H boutique hub, no better.
They are no stronger than the pawls on my SA hubs. They are prone to muck up and they are NOT so easy to clean.
If you need crazy low gears, then that's your problem.
E bikes soon turn defaileurs to mush just as fast, if not worse than a Rohloff14, that now has an E special I heard.
It's a laughable MYTH that my Rohloff is less efficient than a LHT at 2/3 the loaded weight. Mine gets better every day. 19,300 miles with NO problem but the chains.
Rei did buy a Rohloff after, but never updated and quit vlogging.
Me and my bike were 290 lbs, 75% of his total. LOL

Darth Lefty 

It doesn't mean they can't. The reasons for one thing or another come and go. Pinion didn't make big inroads in MTB for a variety of reasons having to do with suspension and people don't want it on road going bikes due to the weight and drag. That leaves them with the serious touring gearing nerds, just like Rohloff. Meanwhile Shimano is selling tons of 7 and 8 speed hubs right now on e-bikes, compatible with whatever brand front drive, giving them more market share of shifting than they would have if they concentrated on a combined e-bike gearbox. My wife's new e-bike is Bosch, Gates, Alfine which seems like a terrific combination of things you'd hate to push around on a non-e-bike

Meanwhile in MTB the aforementioned Nicolai is trying out an enduro bike with the Supre derailleur, which is a much more significant departure from the norm. Lots of things in MTB flame out on their own merit in a few years but have influence down the line, so who knows? E-bike plus suspension has driven some manufacturers away from their trademark suspension designs because they have to put a motor where the pivot used to be.

tcs

And a tip of the hat to those who try.

I thought the principals at Pinion got off on the wrong foot. They said in an interview, "Motorcycles have (frame-mounted) gearboxes - why don't bicycles?" Their starting question should have been, 'Everyone who has tried a bottom bracket gearbox for bicycles has failed in the marketplace so far. Let's figure out why and do better."

tcs

100 years ago chain alignment was a big deal. With modern chains, tests have shown the modest chain misalignment of bicycle drivetrains has close to no effect.

Chainline constant, cogs slid back and forth, 1931:

Darth Lefty 

I saw one of those more recent with the chain ring sliding instead. 1970's maybe. Why was I looking? I had a different chain line idea, and was looking for prior art.

Pratt

One potential advantage of the Pinion, and probably the Roloff, is a symmetrical rear wheel which should be stronger. Not an issue for mere mortals, but strong/heavy/loaded riders in rough terain might see a gain.