Gearing up front pedal trike

[93EXCivic]

Ok so last year I did the Downtown Tri here in Huntsville (tricycle race). It is a team format around a block and I had bought a Razor drift trike to us. It is an absolute hoot to ride but I am spinning so fast that my feet are flying off the pedals well before the end of the straights. I want to swap to higher gearing but I am not quite sure how yet.

One option is to relace the hub to a 22in or 24in rim and get longer cranks. That would require a lot of cutting and welding.

Another option would be to get a bigger diameter tire and slightly longer cranks but the increase in gearing from that would be very limited.

I am hoping there is internally geared hub that might work in this applications. Any ideas?

 

[Wildcat]

I always wondered about the same thing. The biggest front wheel that has pedals are the old Ordinarys (highwheelers) from 100 years ago. Coker recently made the Wheelman, with a 36" front wheel, but it had the same limitations, only one gear that limits your speed unless you can spin fast and can have fun that way. Not me, I need 60-70 rpm at 12-15 mph to ride happy. Here's a vid of the Coker:


The High Roller uses a 26" wheel limiting the speed to about 10mph.

I've never seen gearing, whether derailler or internal added to that type of setup.

 

[Duchess]

There is a geared hub for unicycles, but I believe they're ridiculously expensive and only offer 2 speeds. If you get the hub to spin independently from the pedals (I've seen it, so there's something out there or a way to do it), you can set up a bracket for a jackshaft on the fork, allowing you to pick different ratios by running a chainring on the cranks chained to another sprocket on a jackshaft that has another sprocket riding inside the fork that's chained to a fourth gear that turns the hub. You might also need a chain tensioner. You wouldn't be able to shift gears, but you could increase wheel rpm.

Off the top of my head, I think you could use the same idea for multiple gears, but it gets kind of complicated to make without a machine shop: same idea except the crank runs multiple chainrings of different sizes like any bike with a front derailleur going up to the jackshaft to different sprockets (or same size since the different ratios will be determined by the chainrings at the crank, anyway) that free-ride on bearings on the jackshaft, which now has splines on it. The sprocket bearings would have dog teeth on the outside of the race. In between the sprockets, would be splined steel rings that rotate with the jackshaft and that have corresponding dog teeth on each face to mesh with the ones on the sprockets. The rings could be slid using a fork selector (or maybe a bowden cable, but you'd need a way to keep the rings from popping out of the sprockets) to mesh with either sprocket aside it.

TLDR: take the jackshaft idea of the first paragraph and think of how a non-synchro manual gearbox works to add gear ratios.

 

[93EXCivic]

I remember seeing a dual drive high wheeler in The American Bicycle book.
This one is from the late 1800's. Not the same in the book. Was very confused because it was a profile picture and couldn't see the other side
View attachment 90560

I was thinking about something like this. Fabricating a second crank mount, and running two short chains to sprockets on the current hub.

The current hub does freewheel and I only need one gear. I just need a higher gear.

 

[Grant]

Longer cranks would actually work for that. The penny farthing guys do it.

 

[handyandy1100]

I remember seeing a dual drive high wheeler in The American Bicycle book.
This one is from the late 1800's. Not the same in the book. Was very confused because it was a profile picture and couldn't see the other side
View attachment 90560

There's not an axle connecting the pedals, is there?

 

[Grant]

Take some information from this video .

 

[93EXCivic]

The problem is I can't really do longer cranks without changing wheel size which would require cutting the brace on the fork and moving the brace and brake mounts. Doable but mounting the cranks in a different place gives move flexibility.

 

[MojoK]

You can attack the problem from the other side...clipless pedals and work on cadence. Do you ever do "training rides" on the drifter?

You could also look at a hand-cycle conversion?