Rohloff for 2wd trike axle

[steve browne]

I would like to use a Rohloff hub to drive a Trykit 2 wheel drive conversion axle. The main reason is to get lower gears, a second reason is that I prefer hub gears and a third is that I enjoy working out how to do this sort of thing.

If anybody has done this already I would be very grateful for any pictures or advice.

The spoke circle diameter on the Rohloff hub is 100mm. Do you think it will be possible to use a 30tooth 104mm BCD inner ring by bolting it to the hub shell?

The conversion axle accepts Shimano cassettes. I have no experience of using cassettes as nearly all my bikes use hub gears. Is it possible to fit just one sprocket to the cassette body and use packing spacers in place of the remaining 9 or 10 sprockets?

[Brucey]

.........The spoke circle diameter on the Rohloff hub is 100mm. Do you think it will be possible to use a 30tooth 104mm BCD inner ring by bolting it to the hub shell?

The conversion axle accepts Shimano cassettes. I have no experience of using cassettes as nearly all my bikes use hub gears. Is it possible to fit just one sprocket to the cassette body and use packing spacers in place of the remaining 9 or 10 sprockets?

yes

[steve browne]

Thanks Brucey. That's the all clear for my winter project! Nice to see you posting again too. Best wishes, Steve

[Brucey]

actually you might be better off with a smaller bcd than that;any ring will do providing you can mount it using least three 12.9 M3 bolts and nylocks

[Brucey]

actually you might be better off with a smaller bcd than that;any ring will do providing you can mount it using least three 12.9 M3 bolts and nylocks

further to the above if you don't want to do anything to the hubshell just use more/smaller dia bolts + threadlock

[cycle tramp]

I'm guessing that the hub is supported/suspended somehow in the trike frame, between the crank and the rear axle of the trike? - and that suspension also includes a proper mounting to deal with the torque that the hub generates......So there's a chain which goes from the crank, to the hub and then a second chain* running off the disc brake mounts** of the hub to the rear axle?

At which point you may have to speak with the manufacturer of the conversion kit...

..And at the risk of sounding like wet-sponge-damp-shorts; Why?

Dérailleurs are not going to affect your wheel dish, are going to be kept cleaner by the fact that it's not close to your rear wheels and you can get lower gears than a rolhoff by using a triple chainset and being picky over the number of teeth the small chainring has. plus they're going to be easier to fit and not as expensive....

* and some way to keep both chains under some sort of tension
**because that's where I would mount the 2nd sprocket rather than use the spoke holes

[cycle tramp]

...at this point if I was going to use a hub in a trike, I'd actually reverse it, so i'd have two front wheels for better braking and handling* have the hub in the single back wheel where it was designed to go, without the need for any specialist transmission parts...

..that's either a kendrick tricycle or something like roman road used to build.. or a recumbent trike. Given the cost of the trike kit and then the adaptions there after, including the cost of the hub.... a second hand recumbent trike may work out cheaper....

(*...ooh.. they'll be letters)

[Brucey]

top tip; I have used carefully-ground slots [made using a die grinder] to mount a similar 'chainring'. Slots [+grinding] meant I could use steel sprockets which last much longer.

[cycle tramp]

.. sadly I'm not able to find a bolt on kit to convert your bike into a trike with two front wheels, because such a thing crossed my mind, yesterday when I encountered a lane three inches deep in cow slurry, under which was a broken track with sand bars and compacted clay mud... every tenth pedal stroke, the rear wheel broke traction and things went sideways...

[Tigerbiten]

I assume your going to sett the Rohloff up as a lay shaft and run the second sprocket off it on the same side as the first sprocket.
That way it should hopefully line up with the big sprocket on the cassette.
So in theory you can then use the conversion kit without modding it.
Search for "Kettwiesel trike rohloff speedhub" as I think that's what your aiming for.
But I think the "fun" bit will be making sure neither chain line hits the seat/chain stay.

Luck ....

[cycle tramp]

I assume your going to sett the Rohloff up as a lay shaft and run the second sprocket off it on the same side as the first sprocket.
That way it should hopefully line up with the big sprocket on the cassette.
So in theory you can then use the conversion kit without modding it.
Search for "Kettwiesel trike rohloff speedhub" as I think that's what your aiming for.
But I think the "fun" bit will be making sure neither chain line hits the seat/chain stay.

Luck ....

That's an interesting bit of engineering, but the trike kit conversion still requires some sort of sub frame to mount the speed hub between the trike axle and the cranks, and it's worth remembering that if you don't use a prescribed drop out for the torque arm/mounting from the hub, rolhoff may invalidate the warranty on the speed hub... and apart from moving the hub, I'm not sure how you would keep either if the two chains under tension when the chains started to wear..

[Tigerbiten]

Chain tension's easy, just fit the Rohloff in horizonal dropouts.
That will let you keep one chain at the right tension, chain tugs may be needed.
Then just use a single speed chain tensioner on the other one.
The dropouts would also take an anti-rotation axle plate so that's covered as well.
It the frame and the chain lines that the interesting one.
My thoughts were something like .....
Short chain stays off something like a Brompton.
Then a plate with a slot in it for the Rohloff.
Then another set of short chain stays to the original dropouts.
That would keep the total chain line as straight as possible.
And getting the chain from outside the rear triangle to inside it easy.

[cycle tramp]

The torque mounting for the rolhoff hub isn't an inconsequential item... here's an approved one from a Thorn frame....

It's cast stainless steel and is proper thick.

Whilst anything can be done, we are talking about a conversion (from derailleur to hub gear) of a kit to change a bicycle into a trike.... given the cost of the trike kit itself, then the cost of the hub and subsequent time/money in building the conversion (of a conversion)..plus the fact that on a two wheel drive trike, I can't actually see the downside of the derailleur system (other than wear), I'm just wondering if it wouldn't be easier to accept the trike kit as it was originally designed or for the cost of the trike kit, rolhoff hub and everything else, purchase a whole trike, either kendrick, two wheel drive or recumbent...

[Brucey]

IIRC there are lots of trikes out there running modified IGHs with no tensioner on the second [short] chain. I don't expect anyone competent to sweat much making a suitable cradle for the hub, either.

[brumster]

The torque mounting for the rolhoff hub isn't an inconsequential item... here's an approved one from a Thorn frame....

20231015_151204.jpg

It's cast stainless steel and is proper thick.

Whilst anything can be done, we are talking about a conversion (from derailleur to hub gear) of a kit to change a bicycle into a trike.... given the cost of the trike kit itself, then the cost of the hub and subsequent time/money in building the conversion (of a conversion)..plus the fact that on a two wheel drive trike, I can't actually see the downside of the derailleur system (other than wear), I'm just wondering if it wouldn't be easier to accept the trike kit as it was originally designed or for the cost of the trike kit, rolhoff hub and everything else, purchase a whole trike, either kendrick, two wheel drive or recumbent...

It's worth noting the Thorn cast dropouts are suitably strong enough for the axleplate /torque arm. I've seen some horizontal dropouts bend when the same axleplate has been used.