I want put a frame mounted IGH on a single speed 29er. I've seen that this has been done. I believe I can do the fabrication. Not sure about everything on the bike/mechanical side. Not sure about how to handle the chain line. Either the crank to IGH or the IGH to sprocket won't be in it's original location. I guess the sprocket to IGH would use the original chain line, so the crank might need to be spaced out to line up with the second sprocket. Also not sure about putting two sprockets on the internal gear hub. Any advice would be greatly appreciated.

Sounds like a Pinion gearbox: PINION | DRIVE TECHNOLOGY | | GEARBOX FAMILY P1.18 / P1.12 / P19CR / P1.9XR

Frame Builders have used Rohloff Hubs as mid drives .. Full Suspension off road .

primary drive Chain, Short, to the hub cog, and final drive down the left leg (rear swingarm) from a 4 bolt chainring where the disc would Mount.. With other disc mounts you would have to seek out 6 bolt Cogs they are Made.



Back in the 50's when I was Bodging together my 3 cubed 27 speed (3x3x3) my fellow Boy Scout friend's Dad
made a 2 hub 3 by 3.

a 2nd 3 speed hub was mounted high Up on top of the seat stays-seat tube triangle , and used 2 chains,

primary chain from the crank to the hub cog, final drive off the hubshell with a sprocket attached to where the spokes mount ,
It drives the other hub in the rear wheel .

Now the hubs with such a second chain sprocket are common, made for upright Trikes..

Just got done looking at the trike hubs. So far they all had coaster brakes. Was hoping to start off trying this on a 3 speed.

Not looking very hard I suspect ..
Sturmey Archer | TS-RB3 no coaster brake

and the Disc left end mount Sturmey Archer | S-RK3



laser cut sprockets with 18 little holes , to pop rivet them to any 36 hole Hubshell is a bit more custom work ..

South Bend have any manufacturing left there ?

Not like they use to. Fortunately I have a friend that can fabricate anything. I would still rather use as much off the shelf stuff as possible. Thanks for finding the hubs. More a case of not knowing what I was looking for.

The Top of the rear Triangle 2nd hub has been Proven to work ..

You do have to make the 'dropout' Up There able to take up chain tension , from the crank, the horizontal dropout
may pull up enough to have that 2nd chain within a half link range..

Yea owners hate paying US labor prices (posters here seem to think Bike shop owners & staff get Rich... Ha!)

rather make Bezos Richer ..

Suntour V-Boxx

Looks amazing and heavy and expensive.

Like Pinion , the frame is Built around the transmission , not a shade tree conversion of an existing bike frame .

All this. If I remember right, I think this was made primarily for downhill bikes. The Pinion unit Jeff mentioned above is lighter... but still heavy compared to a regular drivetrain.

I remain intrigued by the notion, but underwhelmed by the execution so far...

Intrigued is a decent word, but I think the concept is flawed from the start. How can it not be heavy and expensive?

I'd be intrigued to see some if the FIM small displacement GP Race motor bike transmissions, another version of that type of gearbox

with a lot of gear ratios , because a 125cc 2 stroke GP Motor has a high RPM, & narrow power band..

In theory, could the IGH be placed at the bottom bracket? Crank drives the axle, chainring driven by the hub shell, reverse the hub (make DS the NDS) so the freewheel mechanism works in the suitable direction. The ratios are typically from 0.5 to 1.5, so they'd be just as appropriate reversed to 1.5 to 0.5.

I haven't thought this through, obviously . . .

[MENTION=63590]jyl[/MENTION], yes, Schlumpf makes a geared crank.

Have to wonder how they did that ... since the gearing changes the ratio of rotation between the cog and the Hub-shell
(where it would be spoked into the wheel ) As I said, the straight forward method is a 4 bolt cog (normal chainring)

that would be Left hand driven..

I'd have to Guess they used the chainring riveted to the right Hub flange method


Jack shaft ? 'Under the Hood' pictures would be enlightening


edit; & Florian Schlumpf also made a 2 speed Unicycle hub .. 1 & 1.5:1 I believe..

built into a 24" wheel, kicked into over drive you have a 36" wheel ..

Well, they manage to put a bunch of gears in hubs, and as a concept, it would just mean moving the gears from the hub to some part of the frame... but obviously there's apparently a bit more to it or it would already be a thing.

In addition to the Schlumpf drive geared crank, there's also the less expensive FSA Metropolis Patterson crank.

Cranks withstand more torque than hubs do. They have to be heavier, so gears in the crank have to be heavier than hub gears. Right? I'm just thinking out loud now.

Have used a Mountain drive crank for a Number of years Now. The Swiss Machine work Is quite Nice

IDK what the insides are like , but the torque stop for the reduction gear needs heavier bracing than the 2 overdrive models ..

1) because you kick in the overdrive to go faster , So you are dealing with wind resistance , Not Gravity ..

This will give you a good view of the insides of a Schlumpf crank. It's their two-speed unicycle hub, but the workings are essentially identical.