High power RC motor and drive unit production

[deecanio]

Hi Mitch,

Jozzer was telling me about the split-pi controllers a few weeks back but the only problem we see is the 1.5kw limit at the moment, could be very interesting for the future but as you know i'm into the here and now side of things


Cheers,

D

 

[GGoodrum]

It is hard to describe and hard to draw to show. Basically, the drive unit will consist of mechanical tubing holding the jackshaft bearings and those tubes will be held together with double clamps that look like front fork tripple clamps. The entire unit will be very adjustable and configurable for various layouts.

I am really excited to post pics of it. I will try as hard as I can to get a prototype machined ASAP.

Matt

I'm still confused, but as I understand it, you will still have both single and two-stage versions of this, right? I'm thinking this would be a good fit for my NeuMotor 2215-3Y, with the P62 planetary gearbox on it. The kV of this motor is 480, and the GB provides a 6.75:1 reduction. Here's what it looks like:

I want to use this with a Nexus 3-speed rear hub, which has ratios of about 1.33:1, 1:1 and .75:1, so I figure I need another reduction of around 6:1 in order to get the speeds and torque I'm looking to get. What I'm thinking is putting your new widget in "series" with the existing pedal drive, using two oneways/freewheels, with two sprockets, on your output jackshaft, one that drives the rear hub, and a second one that connects to the front chainring. That way I can still use the pedal drive, with the 3-speed hub, just like stock setup.

I seem to remember you tried a Power Jazz controller, but had some issue with it. I have one of those that I was planning on using, but I'll pick up an HV110 and do the cap mod., if you think that's a better option.

-- Gary

 

[recumpence]

Hey Gary,

Yes, for your application, you will need a chain drive as a belt would not take the torque in that situation. I can set you up with a 6 to 1 .25 pitch chain drive. I would need your motor in hand to do the machining needed to mate it with the mount plate.

Also, what is the output shaft diameter (maybe 6mm)?

Oh, the guys on RC Groups are looking for you. The keep mentioning it "Where is GGoodrum?"

I think myself and Askman are about the only ones who know what is going on. :wink:

Matt

 

[MitchJi]

I want to use this with a Nexus 3-speed rear hub, which has ratios of about 1.33:1, 1:1 and .75:1, so I figure I need another reduction of around 6:1 in order to get the speeds and torque I'm looking to get. What I'm thinking is putting your new widget in "series" with the existing pedal drive, using two oneways/freewheels, with two sprockets, on your output jackshaft, one that drives the rear hub, and a second one that connects to the front chainring. That way I can still use the pedal drive, with the 3-speed hub, just like stock setup.

-- Gary

Hi Gary,

I plan to do exactly the same thing ("with two sprockets, on your output jackshaft, one that drives the rear hub, and a second one that connects to the front chainring") but using Davids motor. I was planning to ask Matt what he would do to will help accommodate that as soon as I gather a little more information.

If two of us use the same setup it and purchase them at the same time that might help?

I think what we need on the output jackshaft is:

• 1. The sprocket that connects to the front crank needs to freewheel so that the motor doesn't drive the pedals.
  
  2. The sprocket that connects to the rear hub needs to be fixed because if it freewheels pedaling won't apply any force to the rear sprocket.
  
  3. The output shaft (or both sprockets as a unit) need to freewheel if you want to pedal with the motor off and not have that force go back through the gears.

There are at least two ways to accomplish number three above. I'm not sure which is easiest, I think number 1.
1. Both the sprocket and freewheel can mount on the shaft and the shaft can freewheel (freewheel or oneway on the input side of the final shaft).
2. The guts from the right side of a freehub can be mounted on the output shaft. This whole assembly will freewheel. Then a fixed sprocket and freewheel can be mounted on the freehub.

Number one might be easier but would require a freewheel on the input side of the final shaft.

Option two would not require any modification to his drive except that it would be helpful if the final shaft could be modified to accept the freehub.

 

[CNCAddict]

For those interested, I've finished up the motor design for the first 2 prototypes. I'm building one to test myself, and sending the other one to Matt. I've lengthened the stator some to final dimensions of 6050. The weight will be pretty high at 3.5lb but it should also allow about 10lbft of torque continuous at the higher rpms (more cooling). For a 15:1 reduction that's 150lbft of torque at the rear wheel. If I do a 3 turn it will have a Kv of 155rpm/v and will need ~200A to get 10lbft. A 2 turn will be around 230rpm/v and need ~300A to do the same. I'm talking with Kelly about some future controllers, and they apparently have a sensorless in the works. 72V and 100A (not sure continuous or peak). I'll initially test this motor out with my spin200, and we'll see how it goes. Anyhow, I should have all the parts in a few weeks and the motors completed a few days after

Matt, the 40mm motors will be done really soon. All the production parts are done and they should be wound up in the next few days

 

[GGoodrum]

Hey Gary,

Yes, for your application, you will need a chain drive as a belt would not take the torque in that situation. I can set you up with a 6 to 1 .25 pitch chain drive. I would need your motor in hand to do the machining needed to mate it with the mount plate.

Also, what is the output shaft diameter (maybe 6mm)?

Oh, the guys on RC Groups are looking for you. The keep mentioning it "Where is GGoodrum?"

I think myself and Askman are about the only ones who know what is going on. :wink:

Matt

Yes, I definitely think the chain drive would be better. I remember trying to add a belt drive "extra" stage to a big Ion helicotper, so that we could use a Neu 1521 motor, but even with the Kevlar-reinforced belts, they would shread with the power we wer trying to put through them (5kW+, or so...). We originally tried gears, but even doubling them up, the nylon gears would melt. With the Kevlar HTD 9mm belts, I think we could get 2-3 flights before they came apart.

I barely have enough time to spend over in this world, so I haven't been on RCGroups in awhile. When I get to the point that I can give up my aerospace consulting work, maybe I'll have time to do both, but not now, unfortunately. Maybe you and Andrey can let those who are interested know this. I've also talked with Fred Bronk a bit.

The output shaft of the P62 gearbox is actually 14mm. It is a real beast. I think the output shaft diameter of the motor, going into the GB is 8mm. What about using the PowerJazz, worth a try? If you PM me your address, I'll send you the 2215/P62, for whatever 'fit" checks you need to do.

I'm still trying to decide which bike I'm going to install this on. I have a 16" Dahon Curve D3, which has a 3-speed S-A hub (similar to the Nexus 3...), but I'm thinking I will try putting one of the new BMC geared hubmotors on this. I also have a 20" folding bike that currently has a Cyclone 1000W setup. Other than being a bit noisy, this performs quite well, even on 48V (16s4p a123s...), so I'm probably going to leave this alone. With the power this Neu-based setup will be capable of, I'm now thinking the best choice might be to replace the front-mounted 5304 on my wife's Townie. This would solve several problems. this Townie came with a Nexus-8 hub in back, which also has an internal hub brake. The front wheel also has a hub brake, and the fork doesn't have mounts for standard V-brakes, or for disc brakes. I had the 5304 mounted on the front, and used some coiled wire/retifier-based "ebraking" as the front brakes. This worked okay, but the pushbuttons I was using kept failing. I was also woried about putting this much power (72V/50-60A...) through the stock aluminum forks. I then decided to replace the front fork with a heavy-duty steel mountain bike fork, but it took awhile for my local bike shop to find one that would fit the Townie headset. They finally did, but now there is an issue with getting a V-brake setup that would fit properly with the big Fat Frank tires that came on this bike. There is a clearance problem, something to do with where the V-brake mount is on this fork. I don't know, but at this point, I think what I want to do is put this back stock, with the standard fork and hub brake setup, and install this Neu-based setup, with your new widget, in a fashion like wht Mitch and I have been discussing, which is basically in series with the pedal drive. There is definitely lots more room to work with, on the Townie, and even on a 48V/16s a123-based setup, I think this will have tons of power. Having the 8-speeds on the Nexus will provide even more options, I think, although I doubt that any more than 2-3 gears would ever be used/needed. With 8-speeds you could have stump-pulling low-end torque and still have a 50 mph top end, all on a 48V setup. To me, this is really getting closer to my own personal "holy grail". I love the 72V/80-90A performance you can get from an x5-based setup, but I really want to standardize all my setups on 16s/48V, and make use of these wonderful planetary hubs to get both good low-end performance without sacrificing a "decent" top speed capability.

Mitch, I will have to think about the whole freewheel/oneway issue. I'm having a hard time picturing what you are describing, as I'm not completely up on what is readily available. I know that the rear-type freewheels seem to have big diameters, so some sort of adapter would be needed to make it work for a "jackshaft". but I know that SDP-SI has lots of one-way options that might work just as well. Marrying these up with sprockets is where I get lost. :? I get that we need a one-way/freewheel for the one that is driven by the pedal. This would eliminate having to have one in the crankset, like the Cyclone setup uses. I also see that it would need to be locked to the second sproket that drives the rear hub. I think then all we need is one more freewheel/oneway, somewhere in the reduction box that Matt is doing, right? Is that what you meant by the jackshaft input? I guess another way to look at it is that you have a direct sprocket (i.e. -- no freewheel/oneway...) that drives the chain to the rear hub (which has a freewheel already...), and then there are freewheel/oneways for both the motor sprocket and for the pedal sprocket. How this all comes together is what I don't yet understand.

-- Gary

 

[recumpence]

Hey Gary,

14mm should be doable. I can lathe the sprocket open to accomodate it.

I may make the face plate of the drive unit "Blank" to be machined for each specific application. That may be the easiest option.

Your bike will have CRAZY torque with that motor reduced 6 to 1. My guess is you will have near chain snapping torque.

I had issues with my PowerJazz. But, that may have just been a bad controller. One other guy here (don't remember who) is using one without problems.

Anyway, Dave and I went over some production details for the reduction unit. I may go straight to production without any prototyping because my design looks pretty much bullet-proof.

I just ordered $600 of materials (aluminum bar stock in multiple thicknesses, end mills, pulleys, collars, chain, sprockets, etc, etc, etc. Meanwhile Dave is programming the HAAS and the Trak DPM for production.

CNCadict,

Let me know how much cashiola to shoot your way for a 40 series motor and the prototype 60 series. Or we can work out a swap. :wink:

Oh, hey, can you wind one of the 40 series with a 250kv?

Matt

 

[GGoodrum]

A 6:1 reduction works for the Townie, as well, and the #25 chain drive sounds like it will certainly handle the power. Let me know what you need, both money-wise, and if you want be to send you the motor. I'm anxious to see some pics, as I'd like to start visualizing how to mount this setup.

I also have a Hacker A60-18L. This one would need a two-stage widget, I think. If the NM works out, I might do one of my other folding bikes with the Hacker. I notice they now also have an A80 series. These seem to be sized more like what David is doing, but probably not as beefy in the right areas, and a lot pricier. they have some new controllers as well, but these too are uber-expensive.

 

[recumpence]

When I get drives done we can discuss what is needed for your situation. It would be a bit custom, but not too bad.

I have decided to have the motor mount face plates for the reduction machined without any motor mount details. That area will be left blank. That way I can machine each one for the specific motor desired.

I have had quite a few custom requests. I don't mind doing custom stuff, within reason. This drive will be relatively modular. That will allow me to do a few custom bits, but still use the main foundation components. Each setup seems to have its own set of challenges.

I will probably stock a few of David's 40 series and a couple 60 series motors. Actually, it would be great to have a couple drives built up with one of each motor (in a common KV) ready to go for anyone who orders. Then maybe I can have a few different mount plates and what-not that the customer can choose from that will best match their application.

I am trying to keep this from becoming too complicated. But, any time you deal with custom or short run "Boutique" stuff, complexity becomes innevitable.

When we get closer to that point (in a few weeks or so) I can PM you my number and we can talk directly.

Oh, CNCaddict and I spoke at length today. He is setting me up with a E-bike spec 40 series (8mm shaft and 4 or 5 turn 250 to 300kv) motor along with the one-off 60 series to test. I will build a high efficiency setup with the 40 series and a high power setup with the 60 series to test.

Matt

 

[MitchJi]

Mitch, I will have to think about the whole freewheel/oneway issue. I'm having a hard time picturing what you are describing

1. I get that we need a one-way/freewheel for the one that is driven by the pedal. This would eliminate having to have one in the crankset, like the Cyclone setup uses.

2. I also see that it would need to be locked to the second sproket that drives the rear hub.

3. I think then all we need is one more freewheel/oneway, somewhere in the reduction box that Matt is doing, right? Is that what you meant by the jackshaft input?

4. I guess another way to look at it is that you have a direct sprocket (i.e. -- no freewheel/oneway...) that drives the chain to the rear hub (which has a freewheel already...) and then there are freewheel/oneways for both the motor sprocket and for the pedal sprocket.

5. How this all comes together is what I don't yet understand. I'm not completely up on what is readily available. I know that the rear-type freewheels seem to have big diameters, so some sort of adapter would be needed to make it work for a "jackshaft". but I know that SDP-SI has lots of one-way options that might work just as well. Marrying these up with sprockets is where I get lost. :?

-- Gary

Hi Gary,

You got it.

• 1. Exactly.
  2. The sprocket to the rear hub is actually locked to the output shaft which is driven both by the motor and the pedals. The two freewheels pevent the motor and pedal sprockets from driving each other.
  3. Yes!
  4. Yes!
  5. Me too I know what the functional requirements are but I'm not sure the best way to do this. Marcus has been doing this for years. I will try to ask him what he would suggest sometime next week and post his response. Matt and Miles are also experts so we should be able to work out a very good solution.

Matt already plans to have a oneway or freewheel on the output side of his final shaft. If he mounts the oneway or freewheel on the input end of our shafts instead of the output end that would cover most of what we need and I don't think it would be much extra work for him. It would require a larger sprocket than he would normally be using with the freewheel or oneway. If he does this we only need to mount a fixed sprocket and a oneway or freewheel on the on the output side and our drives are complete .

I got the impression that Matt thinks freewheel are stronger and have less friction than oneways so we might be better off with freewheels. If Matt goes with oneways and a 1/2" final shaft another approach, if he doesn't mind, would be for Matt to make a couple units with a 5/8" final output shaft. This would make it easier for use to use freewheel(s) instead of oneways because there are adaptors available for adapting freewheels to 5/8" shafts.

A serial drive to the right side definitely complicates the drive but I don't think its a major complication and once we get that taken care of the tradeoff is we don't need to do any modifications to the bikes. We only need to mount the motor/gearbox and connect two chains. I think if we get it worked out at least a few more people will be interested if for no other reason than the ease of installation.

BTW I asked if the "standard 6-bolt prop flange" output of the A80 Hacker is a problem for Ebike use and Richard responded as follows:

You should look for one that has the shaft coming out of the mount side. If you use a belt or chain, there will be a lot of radial load and you don't want the sprocket to be too far away from the bearings.

 

[recumpence]

Oneways are best in this application for a number of reasons. The main reason is ease of installation. Another reason is the sprocket diameter can be far smaller with a oneway, than a freewheel. Also, a oneway allows the use of any pitch chain, whereas a freewheel restricts the user to 1/2 inch pitch bike chains only.

One foundational aspect of my drive system is a 1 and 1/8 inch OD bearing. That is not alterable (this will become apparent when you see the drive design). THere is no 5/8 inch ID bearing that is 1 and 1/8 inch OD. Of course, a 1/2 inch to 5/8 inch sleeve can be used so a freewheel can be used if needed.

At any rate, for a right side only drive to be used, you will need 3 oneways. A oneway on the secondary input so, when pedalling, the secondary jackshaft will be live with the pedals. Also, each sprocket on the output of the drive system will require a oneway. That is the only was you can have pedal only, motor only, or both without any compromises. This is possible. But, it is not an easy task.

The big Hacker motor can be used. But, you will need a custom framework for an output sprocket to be mounted to the end of the can and supported by an outboard bearing. Not impossible, but not easy either.

Much of these difficulties are why I built my recumbent system as I did. There always seems to be one reason or another why RC equipment is compromised for EV use. But, much of the compromises can be overcome with some ingenuity. I think David's motors and my drive (or any other useable drive system that is readily available) are needed. It is one thing to ask someone to weld a couple tabs on their frame and do some simple wiring. It is another thing, entirely, to make them learn everything about RC equipment, find the right motor, order a bunch of weird drive components, contract a machineshop, do all controller programming, etc, just to ride an efficient and light weight E-bike.

My hope is to reduce that down to a drive that can be purchased and simply welded or bolted on, a basic tutorial on RC equipment and ESC programming (heck, I could always stock a few ESCs that are preprogrammed by me and modded with larger input caps for EV use) and a couple affordable, but high quality purpose-built motors that can even be included with their order. What would be needed, realistically, for the consumer/builder, is to read the RC equipment tutorial, order their components, do some simple wiring, and find someone to weld or bolt the drive on.

Lets face it, this is not for the faint hearted. You need to know which side of the screw-driver to use in order to make this drive work for you. But, it is frustrating that there are so many very capable people in this hobby that merely do not have the machinery to fabricate parts, or the knowledge of RC components to know what to order.

That is where I come in.

Matt

 

[MitchJi]

Hi Matt,

At any rate, for a right side only drive to be used, you will need 3 oneways. A oneway on the secondary input so, when pedaling, the secondary jackshaft will be live with the pedals. Also, each sprocket on the output of the drive system will require a oneway. That is the only was you can have pedal only, motor only, or both without any compromises. This is possible. But, it is not an easy task.

Please forgive me if I'm incorrect but I believe that hooking it up to the sprockets or geared hub on the right side, the way we intend will only require two additional oneways. There will be a total of three sprockets on the shaft.

The sprocket from the crank/pedals drives the shaft (CW) and it needs a freewheel so that the CW rotation of the shaft doesn't drive that sprocket because that would cause the motor to drive the pedals.

The sprocket from the motor/gearbox also drives the shaft (CW) and it should also have a freewheel so that the CW rotation of the shaft doesn't drive that sprocket because that would cause pedaling to push against the resistance of the motor and drive train.

The sprocket to the rear hub is driven by the shaft turning CW so it can't have a freewheel that prevents CW rotation of the shaft from turning that sprocket because if it did there would be no power to the rear wheels. A freewheel to prevent that sprocket from turning the shaft isn't necessary mainly because there is already a freewheel on the hub preventing the chain from pushing that sprocket from the rear.

Much of these difficulties are why I built my recumbent system as I did. There always seems to be one reason or another why RC equipment is compromised for EV use. But, much of the compromises can be overcome with some ingenuity. I think David's motors and my drive (or any other useable drive system that is readily available) are needed. It is one thing to ask someone to weld a couple tabs on their frame and do some simple wiring. It is another thing, entirely, to make them learn everything about RC equipment, find the right motor, order a bunch of weird drive components, contract a machineshop, do all controller programming, etc, just to ride an efficient and light weight E-bike.

My hope is to reduce that down to a drive that can be purchased and simply welded or bolted on, a basic tutorial on RC equipment and ESC programming (heck, I could always stock a few ESCs that are preprogrammed by me and modded with larger input caps for EV use) and a couple affordable, but high quality purpose-built motors that can even be included with their order. What would be needed, realistically, for the consumer/builder, is to read the RC equipment tutorial, order their components, do some simple wiring, and find someone to weld or bolt the drive on.

I hope you don't mind me pointing out that what I want to do comes closer than any other option I am aware of to doing exactly that.

Left hand drive requires fitting a sprocket on the left hand side and probably dealing with disc brake disc issues.

Right hand drive via the crank requires a freewheel on the crank.

Once the drive is set up correctly right hand "serial drive" (name coined by Gary) only requires mounting the drive/motor and connecting two chains.

Lets face it, this is not for the faint hearted. You need to know which side of the screw-driver to use in order to make this drive work for you. But, it is frustrating that there are so many very capable people in this hobby that merely do not have the machinery to fabricate parts, or the knowledge of RC components to know what to order.

That is where I come in.

Matt

Its more than having the machinery to fabricate the parts and its more than knowing how to use the machinery. Your ability to design and build parts that elegantly and efficiently solve the issues at hand is a very important piece of the equation.

I think I can safely say that many of us really appreciate your efforts

About May or June I decided to build an Ebike and started to study the options. Your recumbent project was what triggered my desire to power my Ebike with RC Components. Your decision to build and sell a drive triggered the decision to actually use RC components (before that I was not sure it was feasible). And last but not least your request to David to build a motor designed for this purpose means that the price/power/quality equation is vastly improved.

Thanks! Thanks! Thanks!

Mitch

 

[lawsonuw]

One foundational aspect of my drive system is a 1 and 1/8 inch OD bearing. That is not alterable (this will become apparent when you see the drive design). THere is no 5/8 inch ID bearing that is 1 and 1/8 inch OD. Of course, a 1/2 inch to 5/8 inch sleeve can be used so a freewheel can be used if needed.

And that is one of the reasons I like using metric sized drive components and bearings. Fairly thin section bearings DO exist in metric sizes. A 61903 trade number bearing is almost a 5/8ID 1.125OD bearing Hm, with a hard shaft only keyed at the ends and some thrust washers McMaster #8258K21 would work. (McM# 7929K21 with no seals)

Marty

 

[GGoodrum]

I totally agree with all Mitch's comments. I too think that this will be the easiest setup to install, for the reasons Mitch mentions. One big advantage of this sort of approach is that we can take advantage of the existing gearing. This means you can get away with a moderately-sized motor and get great performance.

I'm still trying to visualize what this gearbox is going to look like. Actually, I guess it is not really a box, right?

 

[MitchJi]

Hi Matt,

I want to clarify that what I'm hoping for is that between input from Marcus, you, Miles, Gary and other forum members we can work out a good way to accomplish what we want. At that point I don't want to ask you to do any more than is convenient for you. If you would be kind enough to sell me a box that is a close to what I want as is convenient for you plus I know exactly what I need to have done locally to finish it off that would be wonderful.

If that turns out to be your generic solution minus anything I don't need, that I can have finished locally will be so much better than what I could have designed or afforded to have built without your help that I will be really really grateful to get that much.

If it turns out to be a complete solution that would be even better but its more important to me to minimize any inconvenience to you and to compensate you for your time and trouble than it is to receive a turnkey solution.

Thanks Again!

Mitch

 

[recumpence]

I gotcha. I do appreciate the kudos. We shall see how well it performs when all is said and done, though. I am doing my best.

This drive system will definately require some mounting labor and/or some custom work to make it fit each different bike. However, hopefully, it will not be too daunting for the technically adept.

I am just leary of those who want a turn-key drive system. This aint it. This is a high-end item for the elite who are deep into E-biking, not those who want a $200 complete E-bike to get them 1 mile to work.

After reading that thread about the CA in the testing and reviews section, I am more aware than ever that I need everyone to know what this drive will do and not do and what is required to make it work.

I am really excited about the state of E-bikes right now!

Matt

 

[voicecoils]

...I am just leary of those who want a turn-key drive system. This aint it. This is a high-end item for the elite who are deep into E-biking, not those who want a $200 complete E-bike to get them 1 mile to work....

My own $0.02 FWIW, I think a high-end high-power RC drive system will be best suit high-end, well built bikes. 5kW could easily tear a kmart bike apart. High speeds with poorly built wheelsets, low quality materials, etc are all recipes for disasters IMO.

If budgets are limited, I much prefer older or 2nd hand high quality bikes and components to new but cheap ones.

 

[skydog]

How about twin RC Motors?
It seems others are using dual motors for power in other configurations with benefits to cooling, etc.
With the minimal weight of the RC motor it seems there would be a small penalty to pay.
Cheers,
Rob

 

[recumpence]

Rob,

RC motors are so powerful for their size and weight that a dual motor setup is really not needed. But, there are a few benefits I could think of to running twin motors.

I just met with my production machinist. The drive design is looking good. The main body of the unit is modelled and awaiting material to start cutting.

Matt

 

[etard]

Skydog,
I tought about two motors too, but then after you go into all the extra hassle of two controllers, dual throttle input, syncrinising two motors so that it is efficient, splitting voltage, extra drive gears, etc...
It is not worth it, unless you are using brushed motors. All you have to do is watch the video of Matt's recumbent blasting across the screen to realize one of these lil outrunners geared to our needs is more than enough.

Voicecoils,
I completely agree with you. I would much rather have a nicely built bike from 10 years ago then a similar priced bike for $500 new.

Matt,
Will you be testing the first prototype on your DH bike? I was wondering if your rear swingarm was aluminium and how you were going to mount your drive (welded tabs, screwed directly in, strapping)? Also, I have some extra carbon fiber sheeting from my friction project, could any of this be used instead of aluminum? It's pretty thick (4mm), seems very stiff too.

 

[recumpence]

I will be using one of my production drives on my mountain bike, yes. But, I will not be prototyping the drive per-se. The drive is going straight into production. The reason I am going directly into production, rather than a time of prototyping is, I am relying on my recumbent drive system R&D and applying that to this drive. I will be using the same 15mm wide, 5mm pitch main belt (good for over 5kw) and a .25 chain drive second stage. This setup has proven very good durability and longevity on my recumbent. The main difference between my recumbent drive and the production reduction unit is the reduction famework. The production framework is ALOT beefier than my recumbent drive. Actually, I may go to one of the production drives for my recumbent as well. The production drive is a hugely rigid design. So, the framework for the drive is overbuilt (but still light) and the drive components are well tested. The only question mark in my mind is the oneway for the output sprocket. I am not 100% sure a 1/2 inch ID oneway will tolerate 5kw at 16 to 1. We shall see!

My mountain bike is aluminum as is my swingarm. I will probably mount my drive in front of my bottom bracket off the swing arm pivot bolts. The mounts will be custom, while the drive itself will be a totally stock production 2 stage drive.

CF is awesome for mounting brackets. 4mm is about perfect for these type of mounts as well.

The drive will be mounted using a couple flat plates that can be welded or bolted to the frame. But, you can make your own brakcets if you want. The mounting holes are 1/4-20 threaded holes 1 inch apart on the drive center brace. That brace is 1 and 1/4 inch thick aluminum billet. So, you would end up with two plates parallel to each other, 1 and 1/4 inch apart mounted to the drive with 2 1/4-20 screws each that are 1 inch apart.

I cannot wait to show you guys this thing. Dave's comment was "This thing looks like it belongs on a bike". :wink:

Do I hvae you Guys in suspense?

Matt

 

[recumpence]

Ahh, UPS just delivered about 35 pounds of 6061T6 bar stock.

Oh, yes, shiney parts are comin!

Matt

 

[deecanio]

Do I hvae you Guys in suspense?

Matt

Maybe just a little :lol: :lol: :lol:
By the way Matt, would i be right in thinking that your 26" mtb and my 25" would practically have identical reduction?
Also were you guys discussing the possibility of reduction to a point you cou could drive through the existing gears?
Anyhoo hope the drives are coming on well, im in for one at least and prolly a pletty to go with
Any idea when you'll post some pics?


Cheers,


D

 

[swade]

Matt

Also were you guys discussing the possibility of reduction to a point you cou could drive through the existing gears?

That would make me weep uncontrollably with joy.

 

[recumpence]

The two stage version is capable of 24 to 1 reduction. That may be increaseable to about 30 to 1 depending on a couple things.

So, yes, it could be setup to run through the chain drive on the right side especially if you consider running a .5 pitch sprocket with a low tooth count on the output shaft.

The only issue with Super low reduction is the small motor pulley required to achieve that super low reduction requires a very small motor pulley. That small pulley (maybe 10 or 11 tooth) will not have as many teeth engaged and, therefore, the primary belt could skip more easily. My recumbent primary pulley on my recumbent is 22 tooth. That gives me enough tooth engagement for 7kw of power.

Matt