My RC Mid Drive with Single Stage Reduction
- Thread starter FZBob
- Start date
FZBob said:
Initial results are in on the O-Ring noise reduction experiment. I have three rides with O-Rings. Remember that there are NO freewheels in this mid drive. If I pedal, the motor turns...
Pedaling without throttle - No chain noise ever. It's gone. Yay! The quiet soothing whir of the motor is just audible.
Light throttle - up to around 80 watts - At the start of the ride, the chain is almost silent. (freshly lubed chain). Late in the ride, (as the lube wears off), there is just a bit of noise, but less than before. Also, the noise is much less harsh. Less high frequencies.
150-500 watts - Some chain noise audible, increasing a bit later in the ride. Again, less harsh than before.
O-ring wear - None seen so far.
Next steps - I ordered some square section O-rings of the same size. Hopefully more cushion later in the ride...
I'm curious to compare this to the belt drive when parts arrive...
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It's been a while and I've been meaning to post an update. I'm spending the winter down in Lake Havasu, and riding quite a bit out in the desert. Short story, the bike and motor have been running great. I just charge the battery and lube the chain. The power delivery is very refined and seamless so technical climbs are a joy.
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TL;DR...
So my goal was 250 watts of ASSIST for climbing. Also light weight, simplicity and low hassle factor. This system delivers 500 watts when I want it - for those really steep nasty technical climbs. I typically ride about 10 miles, climb 1000' total, and use 50 to 90 watt hours.
I have over 700 miles of hard dirt riding so far. The chain has stretched less than 1%, and seems to be stable. I lube it every ride, same as the bike chain. I have never cleaned it, so it is covered with a thick protective layer of oily dirt... It appears that it will easily last as long as the bike chain.
The VESC controller works great. I have not even looked at it in ages. I have probably used 5% of it's capabilities. I really like the throttle expo. Highly recommended.
No freewheel on the motor - direct drive. Probably the best part of the whole thing. Since the motor is always spinning, it just picks up totally seamlessly and in a very refined manner when I bring in the throttle. That slight delay and CLACK as the freewheel takes up on a normal drive is just not there. That makes it far nicer to pick my way through technical terrain and blend in a bit of power as desired without upsetting the bike. Also, no constant freewheel clicking! Spinning the motor takes about 6-8 watts - way less drag than switching from a Kenda Nevegal rear tire to my current Specialized Slaughter (great rear tire...) I very rarely use power on the flats, and have NEVER noticed any drag.
Chain noise - There is some under power, but I don't notice unless I listen for it. I have some thoughts, and may try some things in the future.
Motor - Turnigy D5035 125KV. Big Orange. For this conversion, this is the motor. Plenty of power (4S), and it is somewhat shielded against dust. Built for skateboard use. I believe it has an internal fan. Mine hardly gets warm. I tried a bunch of lighter motors and nothing came close.
Wiring - I should address the spaghetti in the bag of wires...
When I get the chance, I would like to test drive some of the off the shelf E-mountain bikes. My bike cost thousands less and is 10-15 pounds lighter so I'm curious to see how they compare. I'm especially curious to see how the PAS systems do as far as delay and controllability. My throttle responds instantly, and is infinitely controllable...
Overall I'm pretty happy with the conversion.
View attachment 1
TL;DR...
So my goal was 250 watts of ASSIST for climbing. Also light weight, simplicity and low hassle factor. This system delivers 500 watts when I want it - for those really steep nasty technical climbs. I typically ride about 10 miles, climb 1000' total, and use 50 to 90 watt hours.
I have over 700 miles of hard dirt riding so far. The chain has stretched less than 1%, and seems to be stable. I lube it every ride, same as the bike chain. I have never cleaned it, so it is covered with a thick protective layer of oily dirt... It appears that it will easily last as long as the bike chain.
The VESC controller works great. I have not even looked at it in ages. I have probably used 5% of it's capabilities. I really like the throttle expo. Highly recommended.
No freewheel on the motor - direct drive. Probably the best part of the whole thing. Since the motor is always spinning, it just picks up totally seamlessly and in a very refined manner when I bring in the throttle. That slight delay and CLACK as the freewheel takes up on a normal drive is just not there. That makes it far nicer to pick my way through technical terrain and blend in a bit of power as desired without upsetting the bike. Also, no constant freewheel clicking! Spinning the motor takes about 6-8 watts - way less drag than switching from a Kenda Nevegal rear tire to my current Specialized Slaughter (great rear tire...) I very rarely use power on the flats, and have NEVER noticed any drag.
Chain noise - There is some under power, but I don't notice unless I listen for it. I have some thoughts, and may try some things in the future.
Motor - Turnigy D5035 125KV. Big Orange. For this conversion, this is the motor. Plenty of power (4S), and it is somewhat shielded against dust. Built for skateboard use. I believe it has an internal fan. Mine hardly gets warm. I tried a bunch of lighter motors and nothing came close.
Wiring - I should address the spaghetti in the bag of wires...
When I get the chance, I would like to test drive some of the off the shelf E-mountain bikes. My bike cost thousands less and is 10-15 pounds lighter so I'm curious to see how they compare. I'm especially curious to see how the PAS systems do as far as delay and controllability. My throttle responds instantly, and is infinitely controllable...
Overall I'm pretty happy with the conversion.
crossbreak
1 MW
thx for sharing. Really intersting! I also found: https://www.ognibenechaintech.com/en/prodotti/6/ingranaggi-OE.htmlFZBob said:
nice find!! I will give this a try. Any source for square shaped rubber?
Hello Bob - thanks for a very inspirational thread.
How do you think your 125Kv motor would fare in a wet environment (I'm down in southern New Zealand, we have water and lots of it).
I have several commercial grade 36V, 227W/hr high amperage battery packs that I use in my business that I'd kinda like to use on a bike - following your approach which motor would you chose to go with them (I read in the thread you have had best results using low voltage packs).
Finally, when you are climbing very steep grades, what do you estimate your drive wheel RPM's at (or what cadence/gear combination do you run)
Thanks
Foster
How do you think your 125Kv motor would fare in a wet environment (I'm down in southern New Zealand, we have water and lots of it).
I have several commercial grade 36V, 227W/hr high amperage battery packs that I use in my business that I'd kinda like to use on a bike - following your approach which motor would you chose to go with them (I read in the thread you have had best results using low voltage packs).
Finally, when you are climbing very steep grades, what do you estimate your drive wheel RPM's at (or what cadence/gear combination do you run)
Thanks
Foster
Hi Foster!
If you run it UNDER the frame, it might get gummed up with mud. remember, it's an outrunner, so the case spins.
Long term, the motor bearings may rust, as they are shielded not sealed, but at that point I would just replace them with some sealed bearings from Boca Bearings.
I believe the pouch which contains my electronics is listed as being water resistant at least.
First, will a 125KV motor make good power at low RPM on 36 Volts? 40 to 80 crank RPM, so 400 to 800 motor RPM. This would be a great question for the controls experts here. The PWM controller may work OK with excessive voltage, but I just don't know. I do know that with 11 Volts, the power sucked. Also, higher KV motors tended to want to spin faster, so I ended up tired just from spinning the crank to keep up.
Second is safety. I have whacked my shin with the pedal a couple of times on 15 Volts while walking up steep hills under power. It gets my attention, but not a big deal. Remember, the system is direct drive. At 36 Volts unlimited, I would bet good money it could snap your leg. I believe the VESC can limit RPM, and I know it can limit current, so that may be a solution.
I would still recommend 15V, and the exact motor I used, as I know it works very well. I tried a lot of variations around that design point, and they were all worse. If you change the recipe you may discover interesting things... (You may have heard of the old Chinese curse - "May you live in interesting times"
)
)
Keep in mind that this is designed as an ASSIST, not a main drive. I often use about 50 to 160 watts on medium climbs, sometimes 250 on the difficult stuff, and I seem to hit 500 watts for a few seconds every ride on the nasty steep technical stuff.
I wouldn't hesitate to ride my bike in the rain (except I hate cleaning mud...). The motor is brushless, so no exposed voltage. It is also somewhat shielded. I wouldn't run it submerged on general principals, but I believe it would be OK in a good rain. It is originally marketed as a skateboard motor. Others may have more to add...tentman said:
If you run it UNDER the frame, it might get gummed up with mud. remember, it's an outrunner, so the case spins.
Long term, the motor bearings may rust, as they are shielded not sealed, but at that point I would just replace them with some sealed bearings from Boca Bearings.
I believe the pouch which contains my electronics is listed as being water resistant at least.
Edit: So my initial response was "No", but I'm going to revise that to "I'm not sure". The components should all handle 36V. I have two concerns:tentman said:
First, will a 125KV motor make good power at low RPM on 36 Volts? 40 to 80 crank RPM, so 400 to 800 motor RPM. This would be a great question for the controls experts here. The PWM controller may work OK with excessive voltage, but I just don't know. I do know that with 11 Volts, the power sucked. Also, higher KV motors tended to want to spin faster, so I ended up tired just from spinning the crank to keep up.
Second is safety. I have whacked my shin with the pedal a couple of times on 15 Volts while walking up steep hills under power. It gets my attention, but not a big deal. Remember, the system is direct drive. At 36 Volts unlimited, I would bet good money it could snap your leg. I believe the VESC can limit RPM, and I know it can limit current, so that may be a solution.
I would still recommend 15V, and the exact motor I used, as I know it works very well. I tried a lot of variations around that design point, and they were all worse. If you change the recipe you may discover interesting things... (You may have heard of the old Chinese curse - "May you live in interesting times"
)I'm running 26" wheels, an 11-40 cassette, and 40 and 22 tooth chainrings. On steep climbs, I may be down as low as 2.5 MPH, in the 22/40 gear. I like to spin 60-80 RPM on the tough stuff, and 50-60 on long grinds. It climbs stuff that scares me - if I go over backwards, it will be a long way down... (I should really refrain, but...tentman said:
)Keep in mind that this is designed as an ASSIST, not a main drive. I often use about 50 to 160 watts on medium climbs, sometimes 250 on the difficult stuff, and I seem to hit 500 watts for a few seconds every ride on the nasty steep technical stuff.
StinkyGoalieGuy
100 W
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- Apr 23, 2008
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Nice work, Bob. This would be the ultimate pedal assist if we could figure how to integrate a torque sensor.
StinkyGoalieGuy said:
Thanks, I'm really enjoying it!
I did a quick google and was surprised to not find a solution. The VESC controller is very flexible, however torque sensing PAS is not simple.
Just to play devils advocate, I really like the flexibility and finesse of my throttle. I can vary the percent assist on an instantaneous
and continuous basis. This comes in handy on complex technical stuff, like when I want to add a big instant boost to clear an obstacle without pushing harder on the pedals. Possibly from riding motorcycles since I was a kid...
I probably should test ride some newer consumer E-Bikes just to see how good a modern PAS implementation is. Maybe my opinion would change. If anyone in the South Bay area is interested in trading some riding time...
StinkyGoalieGuy
100 W
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FZBob said:I probably should test ride some newer consumer E-Bikes just to see how good a modern PAS implementation is. Maybe my opinion would change. If anyone in the South Bay area is interested in trading some riding time...
The newer torque sensing PAS systems are very smooth. The harder you work, the more assist it gives. I think to make this work you would have to add one of the torque sensing bottom brackets like the ones from ebikes.ca and use their CA V3 along with it. Then I don't know if that plays well with the VESC. You might then have to use a Phaserunner. This all adds up to about $600.
But having test ridden some of these new torque sensing PAS systems, they fell really nice. If I could get the same feel for $600 + another $300 for your motor, battery and drive train components, I would do it in a heartbeat.
Animalector
10 kW
I have to add to this, the torque sensing factory bikes are very natural "super Legs" you don't actually notice that it assisting you, until you turn it off, then pedal up the same hill...
The downside is that you are still the one doing the work. there is no "throttle blip" over obstacles, if you don't push hard to get over that log or up that rock face, the bike won't get up it.
I would certainly try one out if you haven't already. I came from a background of hub-motors and DIY mid drives, and I am hooked on the factory torque-sensing solution.
Regards,
Andy
The downside is that you are still the one doing the work. there is no "throttle blip" over obstacles, if you don't push hard to get over that log or up that rock face, the bike won't get up it.
I would certainly try one out if you haven't already. I came from a background of hub-motors and DIY mid drives, and I am hooked on the factory torque-sensing solution.
Regards,
Andy
devo1223
100 W
Hey Bob if you are looking for others to ride with and learn about factory PAS these guys seem cool.
I like your solution and plan on copying it soon. Stinky, wouldn't it just be easier to get a TSDZ2?
I like your solution and plan on copying it soon. Stinky, wouldn't it just be easier to get a TSDZ2?
StinkyGoalieGuy said:
I just took a look at the ebikes.ca Cycle Analyst website. This is in the setup Menu:
"SETUP THROTTLE OUT"
"The Cycle Analyst sends the Throttle OUT signal (ThO) to the motor controller via the CA-DP connector. It can be set up as either a variable voltage signal for ebike controllers or as a digital 1-2mS pulse for RC controllers. The min to max output range should be adjusted to correspond to the throttle input range of the controller to ensure the controller is driven to max at full operator throttle and is completely OFF when the operator throttle is closed."
The VESC will take a variable voltage signal directly, it's what I'm using from the Hall sensor in my old Cyclone throttle, which puts out 0-3V (as I recall...). The VESC can supply the ground and +3V supply. I believe the VESC can be configured to accept other voltages. The VESC can also take an RC controller input, I'm not sure of the details. So the Cycle Analyst SHOULD drive the VESC easily.
StinkyGoalieGuy
100 W
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devo1223 said:
That's a fair point. I guess I should read through that thread. Don't know much about that kit.
RC Mid Drive with Single Stage Reduction - Ride Report
I luckily live close to FZBob and got a chance to go ride with him on his ebike a few days ago.
First I would like to sincerely thank FZBob for the chance to try out his bike. He was kind enough to let me ride his ebike while he rode his regular mountain bike with me up some steep trails near his home.
My background - I have been using ebikes for the past 8+ years all self built (mid drives and hub drives). I commute on average around 5000 miles per year on my commuter ebike. I have also ridden multiple commercial electric mtb offerings including the 2019 Specialized Turbo Levo.
My impression of FZBob's system
Weight:
I was shocked by how light this system was. When picking up the bike it feels just like a regular mountain bike.
The bike rides and respond just like a regular mtb. I am not aware of any commercial mtb ebike that can match this in weight.
Assist:
When ridding without assist, I could not feel much resistance from the motor.
Adding motor assist by feathering the throttle felt very natural. I never felt the motor "kicking in" like some middrive systems I have tried in the past. I suspect this could be the programming or the single stage reduction.
Freewheel function: present and not present
You can freewheel just fine as the resistance from the motor is not noticeable but you cannot freewheel when the motor is on. This is something I am not used to and may be something to consider for technical mtb riders who need to have pedals in certain positions during the ride.
What about the noise:
Noise from the motor is not noticeable at low levels of assist (I think below 100W) and become more noticeable as the assist level and RPM goes up. I think slightly more than a BOSCH mid drive but I would need to test side by side to elaborate more.
I ride a completely silent Leaf hubmotor using the PHASE runner and I find the noise of this system not bothersome.
Overall, I think this system is terrific for those looking for a lightweight and low power (250W or less ) system to add on to an existing mtb or any bike for that matter without changing the characteristics of that bike.
My request:
Please consider adding torque sensing via bottom bracket. Having both the throttle and torque sensor can make this system even better.
I luckily live close to FZBob and got a chance to go ride with him on his ebike a few days ago.
First I would like to sincerely thank FZBob for the chance to try out his bike. He was kind enough to let me ride his ebike while he rode his regular mountain bike with me up some steep trails near his home.
My background - I have been using ebikes for the past 8+ years all self built (mid drives and hub drives). I commute on average around 5000 miles per year on my commuter ebike. I have also ridden multiple commercial electric mtb offerings including the 2019 Specialized Turbo Levo.
My impression of FZBob's system
Weight:
I was shocked by how light this system was. When picking up the bike it feels just like a regular mountain bike.
The bike rides and respond just like a regular mtb. I am not aware of any commercial mtb ebike that can match this in weight.
Assist:
When ridding without assist, I could not feel much resistance from the motor.
Adding motor assist by feathering the throttle felt very natural. I never felt the motor "kicking in" like some middrive systems I have tried in the past. I suspect this could be the programming or the single stage reduction.
Freewheel function: present and not present
You can freewheel just fine as the resistance from the motor is not noticeable but you cannot freewheel when the motor is on. This is something I am not used to and may be something to consider for technical mtb riders who need to have pedals in certain positions during the ride.
What about the noise:
Noise from the motor is not noticeable at low levels of assist (I think below 100W) and become more noticeable as the assist level and RPM goes up. I think slightly more than a BOSCH mid drive but I would need to test side by side to elaborate more.
I ride a completely silent Leaf hubmotor using the PHASE runner and I find the noise of this system not bothersome.
Overall, I think this system is terrific for those looking for a lightweight and low power (250W or less ) system to add on to an existing mtb or any bike for that matter without changing the characteristics of that bike.
My request:
Please consider adding torque sensing via bottom bracket. Having both the throttle and torque sensor can make this system even better.
Thanks for the excellent report. I've been pondering this system for some time BUT its "thing" of not being able to stop pedalling while applying motor power is a bit of a deal killer for my intended purpose (I often have to walk beside the bike and power it up a steep climb - and it has a big load on, so its very hard work).
Has anyone ever rigged up/is there available a chainwheel that freewheels ??
Has anyone ever rigged up/is there available a chainwheel that freewheels ??
Grantmac
10 kW
There are many freewheeling chainwheels of various quality. Including one in development which uses a sprag clutch and should be vastly superior.
oaktsh said:
Thanks for the encouragement, I really enjoyed the ride! It was cool to see the bike in action from a different perspective and get some independent feedback.
By the way, we rode 6 miles and climbed 635'. You used 12.5 Watt Hours (Not Amp Hours!!), a record low for the bike! The electric assist only provided about 28% of the energy for the climbs.
You (and others) definitely have me thinking about torque sensing PAS. I have been looking at the Cycle Analyst website lately. It looks like they have torque sensing bottom brackets which would interface with their controller. That plus a throttle over-ride might be a good way to go. At this point it's more of an intellectual exercise, but we'll see...
tentman said:
I briefly had my bike set up as you describe. I used a Freewheel Crankset and HD Freewheel from:
http://sickbikeparts.com/bicycle-parts-and-tools/
You could also use their Freewheel Spider. I made my own spider, as theirs was not available years ago. Also, I set mine up so I could use a 22T inner chain ring.
Put the threaded crank arm and HD Freewheel on the right. The spider goes on the freewheel, all the chainrings (including the motor drive chainring) go on the spider. Get the spacing right, and done...
Some observations - With this setup the motor alone was not really happy without me pedaling. It's a bit too low power for that. However, when I was out in Arizona over the winter, I walked up some very steep singletracks that were too scary to ride up. I used the motor to help drag me up the hills and it worked quite well. (I did quickly learn to keep my legs out of the way of the pedals!)
You do need a square taper bottom bracket, but that opens the door for Torque Sensing PAS...
FZBob said:
Inspiring build - just the right way to go - assist with electrical freewheeling!
Regarding a torque sensing bottombracket - it will not be possible for the torque sensor to differentiate between your leg input vs the input from the motor. The torque sensing needs to be done in the pedal arms themselves (the owner of ebikes.ca did some experiments that he showed her on ES a few years back)
bose said:
That's what I thought too. However, I saw this on the https://www.ebikes.ca/product-info/advanced-pas-kits.html website:
"NCTE / THUN sensors are best for this. They are also the only option for torque sensing mid-drive setups that use a freewheeling right crankset, as motor torque on the right chainring does not cause a torque signal to the sensor; it's only the human leg torque on the left side crank which is detected. "
It appears that this unit just senses the left side, sort of like having the sensor on the left pedal arm, just downstream a bit... Again, I've never used one, so can't really say for sure. In any case, interesting stuff!
I agree with BOSE that adding torque sensor or even a cadence sensor eseenstially make it “Electrical freewheeling”
Of course using the throttle will disable the freewheeling function as the motor is still mechanically coupled to the cranks.
I think adding a torque sensor or cadence sensor is the most elegant way to obtain this freewheeling function without incurring too much weight. Furthermore it will allow the rider to just focus on the ride/climb without having to have another control to deal with.
Those who ride fixed gear bikes will understand why freewheeling is useful on the mountains.
I have to give :thumb: to FZBob for designing this system.
It is so clever and so elegantly executed. On top of that the efficiency is remarkable based on the numbers I observed during my climbs.
Folks this system shines on the climbs with a reasonable amount of rider input in the right gear ratio. It makes the uphill tolerable while still leaving you with enough energy to tackle the descent however you want to. An aggresssive downhill frame geometry is at your disposal if you have this system installed to help you with the uphill - no ski lift needed.
Of course using the throttle will disable the freewheeling function as the motor is still mechanically coupled to the cranks.
I think adding a torque sensor or cadence sensor is the most elegant way to obtain this freewheeling function without incurring too much weight. Furthermore it will allow the rider to just focus on the ride/climb without having to have another control to deal with.
Those who ride fixed gear bikes will understand why freewheeling is useful on the mountains.
I have to give :thumb: to FZBob for designing this system.
It is so clever and so elegantly executed. On top of that the efficiency is remarkable based on the numbers I observed during my climbs.
Folks this system shines on the climbs with a reasonable amount of rider input in the right gear ratio. It makes the uphill tolerable while still leaving you with enough energy to tackle the descent however you want to. An aggresssive downhill frame geometry is at your disposal if you have this system installed to help you with the uphill - no ski lift needed.
Can you elaborate? Do you think a torque sensing bottom bracket could be interfaced directly to the VESC, without using a Cycle Analyst, and keep a throttle override?bose said:
Would this require getting into the firmware? (It is open source, but that would be above my pay grade...)
