Anyone ever come across a true Left Side Drive: crank, chain & cog on the left side.. is it possible? Why would anyone do it ? & how did it work? Just curious.
Pretty sure there are logical reasons for the application, and it IS possible..

ps. Sorry if there is already been a WHOLE thread about this,
I couldn't find it if there is one..

Occasionally used in BMX. Haven’t seen any in regular bikes. Everything on the BMX works but it feels weird to work on them.

Sheldon's:

https://www.sheldonbrown.com/org/gunnar-index.html

Ah, of course Sheldon "Why be normal?" Brown has been there!
Spoke to him on the phone once, nice guy, was going to buy a 'special' fork from him, but it was towards the end sadly,
for him. (...& for ALL of us!) ..so don't know what happened to all his wonderful creations. Anyone know?

I suppose it would be a necessity for someone with one leg, the left leg..right?
Why do BMX-ers do it? Does it have to do with the direction of the track> ?
Or to Psyche others out?

The perfect solution for all those sellers who insist on showing only the left hand side of the bike

BMXers who grind on the right side have used LHD bikes for years. You can buy them stock.

I corresponded with him over the internet, but never met him in person. I did send him the scans of my VAR catalog, which he posted on the web site.

His wife auctioned some of them off over the years.

“I suppose it would be a necessity for someone with one leg, the left leg..right?”

People with one (left) leg still can ride with drivetrain on the right, as long as they have the left crank and pedal.

Unless you can fabricate your own freewheeling mechanism, the left side drive bike has to be a fixed gear. There must have been left hand freewheels for the BMX bikes mentioned. Sheldon's fixed SA hub could have had a lugged drive sprocket. If it was threaded, there was no doubt a lockring thread as well.

As to why? Because you can.

oldschoolbike

Left hand BMX freewheels are widely listed on eBay. Presumably there are hubs to match. Here's something else though:

I found a picture, but not the explanation that is (or was) out there somewhere.

The great Canadian rider and innovator in a conservative time, Jocelyn Lovell, built and rode a track bike with drive on both sides, to give a two-speed automatic for the kilo ride. As near as I can recall and work out again, this is how it worked: The right side had the lower ratio, implemented with a single freewheel snug on the free side of a fixed/free hub. The left side had the higher ratio, and started each run with a threaded cog set loosely on the hub. As the bike was pedalled, the threaded cog would overrun the hub, pushing it outward (thread is “wrong” on the left) until it hit a reverse-threaded (and maybe jambed?) lockring. Then the higher ratio would simply over-run the freewheel, and drive for the rest of the ride would be on the left. The bigger the ratio difference, the shorter the run in low gear. He had to back-pedal the bike to re-set the gears. Implementation would have been reversed and cleaner if he had a left hand threaded hub. I will gladly stand corrected on any of this if somebody knows otherwise.

In several ways, Jocelyn Lovell was Canada’s own Graham Obree.

oldschoolbike

Track racers tried LH drive decades ago to move the RH crank arm/pedal inwards to reduce banking strike when jockeying in a marched spring. Andy

If he'd threaded a regular freewheel on both sides it could have been like a "retro direct" bike. One ratio pedaling forward and another in reverse

https://feltbicycles.com/products/ta-frd-trackbike

The US Women's pursuit team has been on LH drive Felt bikes for years, since the Rio Olympics.

Curious that it's a pursuit bike that Felt used a LH drive on. Of the track events pursuit is likely the least needing pedal/track clearance If a rider is going slow enough to need the added clearance they have lost the race. Andy

Aero not clearance.

I fail to believe that having the drive on the LH side would be any more aero than its being on the RH side. If anything having only left turns on a track it seems to me that a RH drive would be more in the aero shadow than on the LH side. Andy

That's certainly more convincing than all the CFD and track testing Felt and USAC have done on this design.

For most people, the right leg is dominant, just like the right hand. There is presumably a slight benefit in the transfer of the force to the chain being shorter for the dominant leg. The actual choice of the side could have been, though, very much an accident of history.

Jocelyn Lovell ... dual drive ...& interestingly set up: switchable(!). Speaking of which, how did Sheldon get the 3-speed hub to have 3 gears once it was flipped over? There is no information on that, just on the thumb-shifter he adapted a bit.

At least one of the gears of a normal freewheeling AW three-speed hub works by over-running a directional clutch (you can hear the pawls as you pedal), so there is some directionality in the planetary gear set. It's hard to imagine that that would function as a fixed gear, so maybe the fixed 3-speed hub had a different implementation that eliminated any directioanality. Or maybe not, and Sheldon's modification was to block out the gear that didn't like being driven backward.

I had enough trouble getting my head around Lovell's transmission with nothing but a poor photo and single-sided freewheel hub in my hands. I don't think I can do the thought experiment well enough to work out how a three-speed fixed gear hub must work without any artefact or documentary evidence to work with.

oldschoolbike

The 3-speed, fixed gear hubs (ACS, S3X) don't have any pawls.

That makes sense. Sheldon refers to the ACS as having very different gear ratios from the typical AW freewheeling 3-speed and no "overdrive" ratio. There may have been some common parts, but to first order anyway, it was a different hub.

So the question remains, what did Sheldon have to do to the gear shifter? If it was a true fixed gear in all ratios, what would be the problem be with running it backwards?

oldschoolbike

I am not as well versed on the ASC as I am on the S3X, but the latter model's internals had more in common with the wide range 5 speed than they did with the 3 speed. The planet carrier and the ratios are the same as the 5 speed.
I did this video nearly 10 years ago to demonstrate how the S3X works.

My main commuter is a left hand drive fixed gear single speed.

I use SPD pedals, which have poles. So, to make the crankset work, I installed helicoils in the cranks so that I can have my pedals oriented correctly. Rides exactly the same really. The rear hub is set up with a Shimano Deore XT, HB-M756 hub (6 bolt disc front hub), that has the original axle replaced. The fixed cog is bolted to the hub where a disc rotor would go.

Fun bike and to be honest, most people don't even notice that my bike is not "normal".