From their website:
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Finnish firm, RMK, debuts electric motorcycle with hubless rear wheel
- Thread starter robmack
- Start date
25,000 Euro.....
I call BS on their previous claim that the rear wheel is comparable to a regular rim/tire cobo for weight.
It depends which parts they put in swingarm weight and which they counted as part of the rim/tire. I suspect bearings and mounting will be counted in the swingarm so their rim claim may be accurate as you have an aluminum hoop and a tire. Their unsprung mass on the other hand will be way up on a conventional setup.
Chris-CJ
Well-known member
Agreed, the weight equivalency seems unlikely without the use of exotic (and expensive!) materials.
Also as previously posted, dirt and corrosion will affect the longevity of the drive arrangement.
Interesting concept, though!
Yes, the un-sprung weight that every other company spends buckets on to get the weight out of.
I dont know of any motorcycle burning dinosaurs that does 1000km on a single fillup. I’d settle for 300-400km on a charge.
True. But it will only take a few minutes to fill the tank 3 times. The available ev bikes can't even be considered for an ib as they are right now.
I've only tried a trials ev, and i was blown away by the performance tho.
Point taken. Didn’t consider that.
I wonder if bikes can use super chargers or are the components too big to fit on a moto frame.
A big issue with rapid charging is heat. Bikes have a relatively tiny battery and small cooling system. There are things that could improve the situation (water mist for rad, blast chiller for rad, etc) but given the tiny number of bikes that will want rapid charging, I suspect those solutions may be as rare as hydrogen filling stations.
Using EV anything for a very long distance trip will be painful for the next decade at least. Possible but painful.
Mad Mike
Well-known member
I'm in the wheel making biz, goofy stuff like that is done occasionally for industrial equipment.
Tire changes should be easier than on a conventional bike -- the rim should be locked in with a simple thrust ring.
Bearings are also quite simple, a motorcycle wheel doing 300kmh is only running about 1500rpm, a single tapered bearing with a huge ID could do it. More likely a combo of light thrust and load roller bearings as they can run in a simple machined raceway without a carrier.
To get a reduction in rotational inertia, the hub + magnets or windings in the outer hub would need to weigh less than the rim+spokes+hub+rotors they replaced - shouldn't be that hard, not too sure there is a benefit. (I might be remembering this incorrectly but rotational inertia changes on radius and mass, not where the mass is located, so locating heavy magnets near the edge should make no difference).
The expensive part of hubless designs is machining giant hubs. If they went into mass production they might be able to cast then machine (rather than machine from billet). Either way, it's an expensive machine and an expensive process.
They do look cool!
Mad Mike
Well-known member
This is a hard one to guess at. I'm guessing the swingarm could be a lot simpler and lighter if it didn't need to keep the frame straight under heavy torque, with a hubless design there should be no twisting forces on the swingarm from the chain. Also, ev motors are approaching 5hp:lb power:weight, so you might get a pretty light motor in this setup. I doubt the unsprung on a hubless motorwheel could best a conventional rear setup -- but with the right materials maybe.
See post 23, the post that bumped this from 2019.
EV tech allows a lot of innovative design not cramped by the ergonomics of surrounding an ICE engine and exhaust.
I do like Honda's approach. Stick with proven frames....build an EV motor to fit existing frames. Will be my next bike.
www.cycleworld.com
I'm happy with the ergos of the CB300F...would be nice to have some punch. Needs a 300+ km range which with two batteries should be doable. Speeds here are low tho would be interesting to see how much the Gillies eats up the battery.
I'm startled to see some of the little step on EV scooters motoring along at 30+ kph in local traffic alternating between sidewalk and road on those tiny wheels......and mostly no gear on.
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I do like Honda's approach. Stick with proven frames....build an EV motor to fit existing frames. Will be my next bike.
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www.cycleworld.com
I'm startled to see some of the little step on EV scooters motoring along at 30+ kph in local traffic alternating between sidewalk and road on those tiny wheels......and mostly no gear on.
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Why are you sure that it is hydraulic?
I'm currently doing an electric conversion and any motors with regen also have hall sensors to check the speed of the wheel against teh regen braking. Many diy conversions do away with the rear brake and just stick with regen. The second brake reservoir is likely just triggering a pressure transducer going to the motor controller.
The hub motors that I was having quoted actually came with two hall sensor cables because the sensors in the hub motors fail so frequently is was cheaper to just install a back-up on each motor. I've decided to go with a mid-drive motor.
Cool. Where are you going to use this thing when you're done? Arent you making an uninsurable motorcycle?
It's a clean V-Star with a different (lower hp) motor. I'm not the first one to do it. Seems like guys in the UK have the most difficulty registering conversions.
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