TDCM DD-hub/IGH hybrid

[cycborg]

I think this is a great option for vintage bicycles, because mid-drives are very problematic to fit a curved downtube...

I don't think this is really an alternative to a mid-drive. I assume you're thinking of a "series" mid-drive, where the motor's power is transmitted through the normal bike drivetrain? The advantage of that arrangement is that the motor can use the bike's gears to deliver more torque at low speed.

But in this device, you just have a normal DD hubmotor, combined with a gearing system that only transmits the power from the rider, not from the motor. So from a power delivery perspective it's the same as the usual DD-freewheel-derailleur arrangment. Or am I misunderstanding what you have in mind?

 

[panurge]

I think this is a great option for vintage bicycles, because mid-drives are very problematic to fit a curved downtube...

I don't think this is really an alternative to a mid-drive. I assume you're thinking of a "series" mid-drive, where the motor's power is transmitted through the normal bike drive train? The advantage of that arrangement is that the motor can use the bike's gears to deliver more torque at low speed.

But in this device, you just have a normal DD hub-motor, combined with a gearing system that only transmits the power from the rider, not from the motor. So from a power delivery perspective it's the same as the usual DD-freewheel-derailleur arrangement. Or am I misunderstanding what you have in mind?

I think SM was talking about the TDCM motor as is, in its main application, laced into the wheel.
However, thinking about the use of the DTCM as a mid Drive mounted Hubmotor, (teased by your post and never thought about that before) I couldn't see why It shouldn't work. Think about it reversed (cog LH side) used as a Jackshaft, with the pedal input arriving on it via the brake rotor mount from a freewheel crank-set....
I think It should work or I miss something? obviously you loose the regen-ability, but the Sturmey Archer cog in the left position, should drive both the motor and pedal inputs via the IGH (and thus maintening shifting ability) to the rear wheel.

Couldn't well understand How the IGH is coupled with the hubmotor, if the IGH rotor turns solidly with the spoke flanges of the motor Rotor, It should work. Otherwise, were a sort of freewheel mech involved between the IGH and the Motor itself, it should be tricky or not work at all....Mmmmmh maybe I need to think a bit more about that and look about the motor internals to realize that I'm saying BS, but that's it: just spontaneous figuring.....

 

[panurge]

After some pondering and with the motor in my hands :wink: I still do not see any possible issue using the TDCM as mid drive jackshaft if reversed and driving the wheel left side....nobody would correct me?
Anyway, I've starded a BuildThread about a TDCM IGH motor on a Luna Cargo Fat here: https://endless-sphere.com/forums/viewtopic.php?f=4&t=85075

 

[Toorbough ULL-Zeveigh]

sum impatient dood who erazed his post wuz axing y grin doan carry the hi-speed 395 rpm flavour for his 20" wheel.
dey duz now.
happy?
http://www.ebikes.ca/shop/electric-bicycle-parts/motors/igh-395.html

....nobody would correct me?

of course not...
we enjoy seeing flames shoot out. :wink:

 

[panurge]

sum impatient dood who erazed his post wuz axing y grin doan carry the hi-speed 395 rpm flavour for his 20" wheel.
dey duz now.
happy?
http://www.ebikes.ca/shop/electric-bicycle-parts/motors/igh-395.html

Are you emulating my poor English? LoL, I miss the words "sum" (perhaps a latinism?) "wuz" and "axing"

....nobody would correct me?

of course not...
we enjoy seeing flames shoot out. :wink:

well, I will not be the guinea pig, It was just a mechanical theory....

EDIT: If you look the main picture in the Grin Tech website:

the Sturmey Archer shell is simply bolted to the hub rotor. The freewheel is only the one the sturmey archer has built in. So the reversed jackshaft option is possible, at least mechanically, on the paper.......obviously there could be some reliability problems and failures about bearings and freewheel mech, because it is not the purpose the motor and the IGH are intended for. But A TDCM stoked motor....with integrated IGH serving both inputs sounds attractive....^_^

 

[panurge]

I report here part of the last post in my LUNA TDCM build thread, it should be of general interest...

in this picture I've marked the huge difference in leverage radius between the TDCM stator torque arm (the interface insert) and the Sturmey Archer torque arm (flatted axle + plus slotted washer) that is what usually any hubmotor uses...The main concern with the TDCM IMHO is not the failure of that interface, but the fact that it acts only LH side, Again, the next days testing, will hopefully give some answer.
The System runs smooth with a 40+ kph top @50v, It's a bit noisy from stand, and resonance propagates thru the huge alloy frame.....
I've made 20 Km and the rear lacing seems to withstand the bumps of the ancient pavet of Florence.