Revolt Rv-120 -- Sine wave-- Specialized big hit

As seen here http://endless-sphere.com/forums/viewtopic.php?f=28&t=64342 im contemplating doing the same, looks clean.looks like he is using a twin disc hub ?
revolt site/ specs http://www.revolt.org.il/rv-120/

But would like to use a belt drive instead , so is there an easy way ? affordable supplier of belts and pulleys ect that can take up to 15kw , with a similar reduction or lower than the 11 to 52 as in the norco thread but might use 24" wheels, or pos 17" light moto rim, might use a single speed freewheel to keep it simple, ideal goal is a light, high powered good acceleration with a top speed of around 70 km @ 48v or 72v.
How would you do it , has it been done before, pos a best way to do it build thread somewhere you know or is the linked thread the first.

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He has a freehub with an adaptor drive side, that fit into HG splines and offers a standard 6h 44mm rotor pattern, than drilled holes in a big rotor suited to fit a 52t cut sprocket.
There's nothing exceptional in that about the hub. The unclear part for me is that He plans for a LH pedal single speed drive with a rear 16t freewheel, If that is true, this hub should be a true special custom hub, to have freehub drive side and Rotor mount+freewheel LH.

About the Belt option, with an adapter or even with the same rotor adapter that boisrondevens has made, you could virtually fit even an Harley belt on it without the need to think about the freewheel, because built in the hub itself...

An elegant solution I've figured out before for final belt stages on Power bikes is to use a double centertrack setup.... or a double standard bike belt drive too, that could be LL or RR or LR. And this direct drive build is the perfect application for that.
just 2 drive pulleys on the shaft and 2 driven ones both side of the rotor.....and the ability to use just one....the motor in the swingarm is ideal for that....perhaps really the only option for a full suspension bike to run belts of reasonable size, because no flex. With 2 centertracks you can manage enough torque for these insane Power rates, I guess, plus the teeth's shape make sense even for some dirt....

http://www.sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=28

So if you decided you did want to pedal, a shift kit would give you a freewheel and pedal power while keeping the deraileur working with your motor.

Not sure why that might have a problem with the electric, but there's others designed for it.

http://www.sickbikeparts.com/catalog/product_info.php?cPath=26&products_id=180

http://www.sickbikeparts.com/catalog/product_info.php?cPath=26&products_id=181

Thanks Dauntless

panurge said:

About the Belt option, with an adapter or even with the same rotor adapter that boisrondevens has made, you could virtually fit even an Harley belt on it without the need to think about the freewheel, because built in the hub itself...

An elegant solution I've figured out before for final belt stages on Power bikes is to use a double centertrack setup.... or a double standard bike belt drive too, that could be LL or RR or LR. And this direct drive build is the perfect application for that.
just 2 drive pulleys on the shaft and 2 driven ones both side of the rotor.....and the ability to use just one....the motor in the swingarm is ideal for that....perhaps really the only option for a full suspension bike to run belts of reasonable size, because no flex. With 2 centertracks you can manage enough torque for these insane Power rates, I guess, plus the teeth's shape make sense even for some dirt....

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panurge thanks for your thoughts , as you know the we now know all details on the revolt norco thread.
im guessing the loaded top speed @ 72v with a 11-52 reduction in a 24'' wheel would be 75/80 ks ? would the motor be happy?
If you would have a cro at the same 72v what would be the performance differences be? [ im hoping the revolt would eat it 8) ].
As you can see in my sig im doing my first cro build.
feel free to discuss / elaborate all belt ideas with pics if any.
This bike is using a single belt and has a claimed peak 15kw output , but can this be reliable. looks like a 60 tooth rear pulley.

I've seen that with my eyes....It use a Tandem centertrack belt. It should be good to withstand insane power, indeed, but I bet not the motor it mount I've yet stated that on the Eurobike thread.
The cool of tandem centertrack standard is that belts are obviously bigger and longer than the MTB ones. otherwise they are heavy and have limited pulley size range. MTB CT have size from 19-20 to 70t sprokets, much more better but belts are too short for Sprung motor mounts. That's another reason that makes this swingarm mount setup so sexy, to me.
Actually I've roughly calculated that on the revolt-norco (assuming the motor chainstay is about the same of the original pedal one) with a 19-70t double pulley assembly, and a 3.7 reduction factor, 2x 225 belt should work Ok and be long enough even for a bit of tensioning surplus. But at 100v that's a crazy thing to do with a 45kv motor( perhaps 150kph). I think a non bike toothed belt (or double belt) with available or custom pulleys to reach at least 5:1 reduction, should be a better approach assuming you wont ride on wet/mud...
Other options are to get an even slower motor (about 30kv), to make 2 reduction stages, loosing all the benefits of this funny concept, Or to find a good motor with the same Kv that could be driven at 15-18s 100+A continuously and reliably, still maintaining acceptable torque output to withstand the wide range of speed it has to work with.

Well im learning more each day

I think a non bike toothed belt (or double belt) with available or custom pulleys to reach at least 5:1 reduction, should be a better approach assuming you wont ride on wet/mud...

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Im thinking the same and have been looking at automotive timing belt/ pulleys , there must be a huge selection

Or to find a good motor with the same Kv that could be driven at 15-18s 100+A continuously and reliably, still maintaining acceptable torque output to withstand the wide range of speed it has to work with.

Click to expand...

Ive found out that revolt will do custom winds so this could be'' part'' of the solution, unless you find a better motor.

The other is finding some automotive or other industry pulley sizes to suit our needs,im thinking a single drive system a belt of around 20mm leaving the other side of motor shaft [ 20mm] for a additional bearing ed mount and belt adjustment incorporated in the dropouts, what do you think.

After a lot of reading into the dark art of reduction drives ...and as reductions are meant to have superior torque.
Trying to get an idea on acceleration performance against my cromotor hub.
So if both were in 24'' wheels @ 72v -100 batt amps 7200 watts and both had the same top speed, [ cromotor should be 42mph / 67kph and worked out revolt with a 1-5 single reduction 70kph ] Revolt should be 22nm at shaft if im right divided by 5 gives 80 nm at wheel? [ not sure cromotor's any body ? ] who wins and what difference.

That's a very good question. I tried both the cromo and the rv-120. The difference between those two setup is so huge that's it's almost impossible answer in real life condition. you can do some mathematical calculations but in real life it's always different. But money down I'll put my money on the rv120 no doubt. Off-road condition rv-120
For the moment a have 26" rear tires and the torque it's impressive. I can't wait to put on the 24".

Emoto said:

After a lot of reading into the dark art of reduction drives ...and as reductions are meant to have superior torque.
Trying to get an idea on acceleration performance against my cromotor hub.
So if both were in 24'' wheels @ 72v -100 batt amps 7200 watts and both had the same top speed, [ cromotor should be 42mph / 67kph and worked out revolt with a 1-5 single reduction 70kph ] Revolt should be 22nm at shaft if im right divided by 5 gives 80 nm at wheel? [ not sure cromotor's any body ? ] who wins and what difference.

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I think your question is a bit vague....2 wheels at the same speed with the same power will deliver obviously the same torque. doesn't matter which is the motor that drives these wheel, if a direct hub or a super reduced tiny fast motor.
When you gear the rv120 up to reach the same top-speed of a Cromo, then you may easily consider the kv and kt of the system at the wheel, so exactly the same. What makes the difference is the Max torque these 2 motors are able to sustain (*5 on your 5 to 1 reduction with a RV120, minus losses that means 22*5=110Nm -5% on your calcs), but if you say 100 batt Amps fixed, than the only difference will concern the controller, and were it the same one....no difference other than the losses on the drivetrain for the RV120 (but better efficiency I guess) and the >8 Kg of the cromo on the same bike and as unsprung and gyro mass . No doubt the rv equipped Bike will dust the cromo equipped one....

That's right Boisrondevens, real datas and experiences are the only that means....
So we are waiting keen for yours....
I think reliability of the controller, water/mud proofing and lasting of the drivetrain (mostly freehub and chain) are the first question to test/solve.

panurge if my question was vague im just going with what information i have at the moment, i see so i multiply shaft nm by reduction for nm @ wheel.
I was under the impression that reductions had more torque on same configuration/ set up, in a nut shell im trying to justify it against a hub, so apart from unsprung mass, and lighter build [9.3kv cromotor v1 is 10kg and ali stator v2/3 12kg , rv 120 pro 4.83 plus, 1kg / 1.5 for pullys ect ] therefor better off road... and efficiency, any other benifits.
If i knew the cro's nm that would make comparing much easier.
Im also considering the rv 100 only 3.3 kg and a out put of around 15nm at peak(3700rpm). @ 72v 100amp- 49kv if i could get similar performance with jiggling the reduction that would be appealing??... but also a consideration is it has a 12mm shaft. but 1.5 kg lighter.

boisrondevens said:

in real life condition. you can do some mathematical calculations but in real life it's always different. But money down I'll put my money on the rv120 no doubt. Off-road condition rv-120
For the moment a have 26" rear tires and the torque it's impressive. I can't wait to put on the 24".

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boisrondevens merci beaucoup
I /we have been hanging out for some '' real world '' performance data and agree that's what counts, especially before a purchase $$$...
The 24'' will better and if you changed your reduction so you have 80kph top speed you should get better acceleration @ your 100v
If you have any other performance comparison data ect to add just post it man.

I'm not the guy to talk about Cromotor, hopefully some expert/user will put his 2 cents on the thread.
that's what I've quickly collected and then calculated around here (ES):

Cromotor V3 stock

Kv: 9.3 rpm/V
Kt: 1.0268 Nm/A
Rm: 0,084Ω (but there are also different reports from 0.090 to 0.075 :? )
Wt: 12.2 Kg
Km: 3.54 Nm/W^.5 (Kt/Rm^.5)
Specific Km: 0.29 Nm/W^.5/Kg
MAx Cont. Amps: ? (but you suppose 100A and anyway is easily limited there by the available controllers)
Specific torque: 8.41 Nm/Kg (Kt*Amax/Wt) is that believable? how long?

Revolt RV.120 stock

Kv: 45 rpm/V
Kt: 0,2122 Nm/A
Rm: ? Ω
Wt: 4.3Kg
Km:
Spec. Km:
Max Cont. Amps: ? (but again you suppose 100A)
Specific torque: working from Miles calculations http://endless-sphere.com/forums/viewtopic.php?f=28&t=64342#p964803 it is believable a 3.3(Nm/Kg) specific Torque to sustain 65mph (67Nm/4.72ratio => 14.19Nm/4.3Kg) supposedly on an approx. 2.1m wheel circumference, with 100Kg grand and "standard" vehicle/environment conditions)

Now, Assuming 100A continuous instead of the 67A on Miles example (14.2Nm/0.2122Nm/A=66.87A) the specific torque would rise up to 5 Nm/Kg, the question again is: is it still believable....?
Having Rm and no loads from the manufacturer should be normal.....or :?

Looking at a close motor in weight and claimed performances from the "RC" world I found nothing really available and/or with a good datasheet. A bit over (in every field), and inrunner there's the

Astro 4535 @5.3Kg 4T Wye (160A @100V test)

Kv: 80 rpm/V
Kt: 0.119 Nm/A
Rm: 0.023 Ω
Wt: 5.3Kg
Km: 0.784 Nm/W^.5
Spec. Km: 0.148
Max Cont. Amps: 160 A (at least)
Specific torque: 3,59 Nm/Kg

Sorry to be that long It has been useful for me to remind me rules and formulas....
In COnclusion My feel is that both these motors (even if the cromo specs are a bit unbelievable from my unexpert point of view) Should deliver exciting ad Huge torque and power amounts, probably over even the insane "needs" of the superMotoBicycle Guys....

Limits are COntrollers and Handling, stability, and reliability of those Bikes. Saving probably 7kg or more, and mostly from the unsprung mass on the wheel, A mid-drive single stage setup with a motor like the RV could make sense for a Proper FS offroad bike Based on DH standards (well not for the speed at 100V ).
Otherwise, A Full suspension DH or MTB with such a second bike weight centered on the wheel (cromotors and similars) Would be simply, only, the best donor Bicycle in terms of strength, travel, forks and brakes for that crazy heavy and torquey motors, but not a well suited vehicle for that motor in absolute terms....at all, that's my feel.

Just my 1000 cents

I understand the reasoning behind putting the motor in the rear triangle, so the chain tension is consistent, but I'm curious as why I haven't seen anyone put the motor on top of the wheel. Seems like there is never enough space between the bottom bracke and wheel. I imagine that for those of us without access to a machine shop this would be the easiest way to do it. Especially if you could use the rear wheel axle for the motor mount support or the pivot on the top of the triangle. Could just be bolt on that way. If not weld the motor mount on the rear triangle. Much easier to do than a full custom made rear triangle. Any reason why this would be a stupid idea? The only problem I can think of, is not having the motor weight in the best position. These motors however are fairly lightweight and that shouldn't be too much of an issue if placed as low as possible.
Here's a crude drawing of what I am thinking.

HiDirkdiggler,
Regarding your suggested motor position: As well as raising the centre of gravity of the motor and moving it rearwards (both of which are bad effects on a high power bike), it would almost certainly increase the "effective unsprung weight" by positioning the motor where it moves further / faster as the rear suspension responds to a bump.

On a low powered bike for use on road or smooth trails it might be ok.

As Ecobogan has discovered, as the power levels go up, a longer wheelbase is a good thing, and the lowest centre of gravity possible is an advantage, so having the motor low down in front of the back wheel makes sense.

Dave

panurge said:

Now, Assuming 100A continuous instead of the 67A on Miles example (14.2Nm/0.2122Nm/A=66.87A) the specific torque would rise up to 5 Nm/Kg, the question again is: is it still believable....?
Having Rm and no loads from the manufacturer should be normal.....or :?

Click to expand...

I now have offical outputs from revolt now
For the RV-100 PRO it's 50A and 8nm at continuous(3890rpm) , 100A and 16nm at peak(3700rpm).
For the RV-120 PRO it's 60A and 12nm at continuous(3120rpm) , 120A and 24nm at peak(3010rpm).
so now we have an idea.
I also have been looking for a alternative rc motor but the 43 kv single reduction simplicity is hard to beat.

Ideally i would make a custom aluminum frame for the rv 120 but my repainted big hit frame is sitting ready begging for it, and if done well would be the most road stealth build.
Im hoping Using a belt will help towards that goal.
All the pices are falling in place now and Im very close to giving this build the green light every thing looks good just trying to find the right toothed pulleys with a 20/25 belt

in Conclusion My feel is that both these motors (even if the cromo specs are a bit unbelievable from my unexpert point of view)
Should deliver exciting ad Huge torque and power amounts, probably over even the insane "needs" of the superMotoBicycle Guys....

Click to expand...

i like this conclusion ..... Dude thanks and your more than welcome to put your $100. err cents worth in.
The rv 100 still looks atractive at 3.3kg,and 7kw peak, if revolts specs are conservative and a large ali motor mount,and a external fan fitted as commonly used in rc outrunners,
im thinking 10kw bursts might not be out of the question.

Dirkdiggler i would agree with drum keeping the weight down is best especially in a spill, but yes its got its challenges with fitting it at the swingarm base/ pivot. but thats were ill be putting mine.

@dirkdiggler

I you look for the thread from a european cycle convention (don't remember the name or have it bookmarked)
there was a german bike that was taken pics of - a random bike build by a random dude outside the convention.

I think will see there a bike like you are talking about.

dirkdiggler said:

I understand the reasoning behind putting the motor in the rear triangle, so the chain tension is consistent, but I'm curious as why I haven't seen anyone put the motor on top of the wheel. Seems like there is never enough space between the bottom bracke and wheel. I imagine that for those of us without access to a machine shop this would be the easiest way to do it. Especially if you could use the rear wheel axle for the motor mount support or the pivot on the top of the triangle. Could just be bolt on that way. If not weld the motor mount on the rear triangle. Much easier to do than a full custom made rear triangle. Any reason why this would be a stupid idea? The only problem I can think of, is not having the motor weight in the best position. These motors however are fairly lightweight and that shouldn't be too much of an issue if placed as low as possible.
Here's a crude drawing of what I am thinking.

Click to expand...

Sure the unsprung interference will be higher, that said, if we look close at the picture, and figure out the original dropout, than a mount like you suggest isn't that easy....and will interfere with the swingarm travel, but everything should be done. we have a beautiful build by Mattyciii https://www.electricbike.com/custom-build-ebike/ http://endless-sphere.com/forums/viewtopic.php?f=6&t=37207 with the same bike and a swingarm mounted RC motor (althoug 2 stages and with a very unsprung position) and some other....
I would vote for the swingarm mount only at the condition that it's as close as possible to the suspension pivot, that is single stage and belt is on the plans.....
a 2 stage like Mattyciii bike would weight like the same of a single stage with a Revolt RV 120 ...... but is way more big in volume, so you have less chances to get an acceptable mount with the weight concentrated close to the pivot. If you look well, an Astro 3220 with a 5 to 1 belt stage and a 17-20 to 1 grand, complete of freewheel, belt, pulleys adaptors mounts, jackshaft and sprocket weight 4.7Kg and delivers me 4500W continuous and 7500W peaks and 100 to 150Nm at the wheel. Not so far from the paper specs of the revolt, but these are proven.....the revolt Is compact and cheaper so, if performance are comparable and it is reliable, it could be even better......there's still the fact that an inrunner like the astro is waterproof and easy to be cooled...though

Right now im in two minds what direction to go on my next build... so while i decide.. this frame with fox shock and accessories is still up for sale here http://endless-sphere.com/forums/viewtopic.php?f=9&t=58737

Motor looks good is it a outrunner?

evolutiongts Motor in above pic is v1 cromotor ive used those rims on my first build.

Did you decide what to do Emoto? Build using set up like the Rv-120 Norco A-line with a simple direct drive approach or did you chose different? Did you look into those pulleys and belt from this?


I am still thinking of the Rv-120 Hall as a potential motor. But it seems all threads about the Rv-120 have stopped for some reason.
Did anyone do the math for using a 17" moto rim? Will smaller rear wheel make for better working conditions?

I am still considering tu use it on custom bicycle frame, but there is one huge issue. How to fit the motor between the cranks. It is just to long.

Not sure what you mean by "between crank" but the can or the housing of the motor is just 116mm or 4.56 inches long. This motor will fit regarding the width however the length on most swing arms might need to be stretched. And you might need a bracket or something to attach if not motorcycle style swing arm drop outs that let you adjust chain or belt tension.

If you will mount in on the frame yes it will be wide and you must consider the width when you choose where to mount the motor in regards to the pedals and your feet other then that I can not see that the width should be an issue.

Revolt Rv-120 measures.

• 
  [*]Total length: 191mm
  [*]Can length:116mm
  [*]Can diamter: 127mm
  [*]Shaft diameter:15mm
  Shaft length: 45 mm
  [*]Weight: 4.83 kg

Pics of motor and a few pics of different mid drives. Click on the pics to see different ways of attaching mid drives. Or simply get a smaller motor :wink:

macribs said:

Not sure what you mean by "between crank" but the can or the housing of the motor is just 116mm or 4.56 inches long. This motor will fit regarding the width however the length on most swing arms might need to be stretched. And you might need a bracket or something to attach if not motorcycle style swing arm drop outs that let you adjust chain or belt tension.

If you will mount in on the frame yes it will be wide and you must consider the width when you choose where to mount the motor in regards to the pedals and your feet other then that I can not see that the width should be an issue.

Revolt Rv-120 measures.

• 
  [*]Total length: 191mm
  [*]Can length:116mm
  [*]Can diamter: 127mm
  [*]Shaft diameter:15mm
  Shaft length: 45 mm
  [*]Weight: 4.83 kg

....

Click to expand...

that's My "A" Factor
cutting out the backshaft from the re-volt motor you'll get 171mm, probably something could be shaved even from the motor's drive side...
An ISIS 148mm BB+Trial Arms with wide offset should clear the Re-Volt length, I think. My howitzer setup is exactly there (170mm gap)....so in some way it should be also used as "frame mounted" middrive.

Otherwise, mounting it on the swingarm, would avoid any crank interference, and, figuring out a minimum offset distance of about 130mm between 2 possible opposite mounted sprockets/pulleys, my Idea (original imput from Miles) to use 2 centertrack belts (on both shaft ends) should be done, at least on a 150mm swingarm

macribs said:

Did you decide what to do Emoto? Build using set up like the Rv-120 Norco A-line with a simple direct drive approach or did you chose different? Did you look into those pulleys and belt from this?

I am still thinking of the Rv-120 Hall as a potential motor. But it seems all threads about the Rv-120 have stopped for some reason.
Did anyone do the math for using a 17" moto rim? Will smaller rear wheel make for better working conditions?

Click to expand...

Hi Mac,atm im riding / enjoying my first custom frame build [ on 7kw now ] i got to the pulley research stage and thought about the belt noise, and stalled on this build, and am considering another hub build as i love the more silent /less complicated aspect.... but after a while a more performance build will get my attention... even though real rider performance data is thin on the rv 120 i can imagine 15 kw in a belted reduction would be very satisfying .

I also think if this motor is capable of much higher torque ,performance than a cro/ QS http://www.aliexpress.com/store/109978 motor then a 17" moto combo might be prudent , and even better acceleration .
From memory i calculated @ 72v with a 4.7 reduction unloaded speed , EDIT Around 70/75kph i Think.

Also on the between crank clearance discussion [q factor] you can get over sized bb axels up to 200mm from memory, would love to see another rv build.