Time Trial / Road racing Cannondale

[veloman]

Edit: lots of changes to this project. Updates at end of thread.


So it is time to start a thread for my 3rd ebike build. I got just enough done so far to take it around the parking lot, but I need to fix the mount so it doesn't flex. My chain popped off as I gave it more than 1/8 throttle.

This bike is sooo light. Should be at 40lbs. And it's going to be extremely aero, since it's a road racing bike with TT bars. I am going for pure speed AND efficiency on this bike. It's going to the bike that will enable me to sell my car, the bike that will take me 16 miles to my gf's place, on 60mph highways (riding the shoulder, bikes allowed) and roads with no shoulders.... It will enable me to cruise at 35-40mph (with pedaling), to keep me safer and have the least amount of cars coming up behind me. I am calculating (and from anecdotal evidence) that I should be able to 40mph on around 1000watts, while on the aero bars. That may be 1000w from the motor (800w real), and 200 from me. Or I can hammer out 500watts myself and approach mid 40s.....maybe. For easy cruising, I should only be drawing about 250watts at 20mph if I don't pedal. It's all about aerodynamics.... I think we need more of that on this forum.

I'll put up some relavant pics, but I have many more to take.

Specs:

Currie 36v xydj type motor, I think it's 750w, seller on ebay stated 1.4hp and 34amps continuous which would be 1200watts.... It has the 15 tooth roller bearing clutch for a sprocket.

I will be using my 5 Bosch Fatpacks for 36v 11ah. 320 usable watt hours

The rest is just cheap scooter parts, 80 tooth #25 sprocket, chain, mounting plate for the My1018z geared motors, but I made it work for this one. Cheap 30amp Chinese controller, has been working well for 450miles already. It has a 'lock' on it for an on/off switch, which is essential to prevent battery drain or sparks, or the bike coming alive without any throttle. I may move to a 40amp controller to get more power, but then I will definitely need to go to 10ga wiring everywhere, which will be a pain, and the whole system will just be less efficient. I think 30amps will be plenty of power (1200w), especially on such a lightweight bike which i will be pedaling as if I was road biking.

Bike coasts as a normal bike thanks to the freewheel front sprocket.

I tested the no load speed, and it's 70mph or higher... I was freaked out watching the chain at 65mph on 3/4 throttle.

I made a 'custom' adapter that bolts onto the left side of a my rear road wheel... this allows me to keep all my normal road gearing and not try to bend my frame getting a mtn bike disc hub in there.

Best thing about this bike: it is practically silent at low speed, and very quiet otherwise. It's also by the far the lightest ebike I've done.

Even with a gearing of 70mph no load, the motor still can accelerate me about the same as an easy riding cyclist below 15mph (1/8 throttle). That's very impressive for a $60 Currie motor.

[liveforphysics]

Beautiful! I'm also starting to piece together a light weight roadbike, but for doing ebike races rather than commutes.

[veloman]

Thanks, I will post a more complete pic today, it looks a LOT better with the sweet semi-aero front wheel and all. The battery pack easily strapped to the top tube with a bungie cord and piece of clear tape....LOL. easily stolen though.

Yes, this won't be great for commuting, especially with lots of stop and go on rough roads, then worrying about it locked up outside... I will be doing a 4th ebike build as soon as this is done, to replace my Giant ATX.

I need to get myself down to the store for some aluminum to fix that mount.


I wonder if there's any ebike racing around here? I never heard of it.

[knoxie]

Superb!

I was thinking that today whilst out on what has to be the hottest bike ride I can remember and I was on a normal bike yes was thinking that with these new Lipos it opens up great options for folks that dont like the weight of conventional e-bikes and it may entice the road lycra guys in, esp the ones that are getting on a bit in years but want to stay in the younger pack so to speak.

Looking forward to seeing what you do here, I think you could slip a couple of 6s in a little saddle bag under your seat and run a Tonxgin front geared motor nice and simple I think a few other folks have dont this, there are a few other road bike assists which of course is a bit of a hot topic at the moment with the Tour bikes being tested for motors! crazy eh.

Good luck with the build and I am with you as much as I love the powerful bikes I also love just going out on my normal bike as well and there definitely is room for light, efficient and powerful bikes here.

[veloman]

Yeah, it's really funny how motors are now being thrown into the pro doping arena.... right when I start putting motors on my bikes.

Ultimately, I'd like to have a completely stealth motor design that fits inside my bike frame, so the bike looks completely like a normal road racing bike. Not to cheat in races on, but to haul a$$, when appropriate, out on the road and not worry about cops.

I LOVE fast road biking, and if I could always keep my speed at 20-25mph minimum, with hills, then it'd be even more enjoyable, safer, and much more effective for commuting.

This is the future of sustainable, practical commuting! (Well, for those who already ride road bikes anyway. I don't expect non-bikers to hop on a bike like I'm building, they'd kill themselves.)

I am about to finish the motor mount in a few hours, just need to drill some more holes. Then I'll take some pics and test ride it without my bike gears on it yet. It's been a bit of a challenge to securely mount that 6lb motor off the rear of my drop out and maintain even support to keep it from torquing or failing.

[veloman]

I am having a problem with the sprocket, it seems bent 1 or 2 mm to the side and is throwing the chain off... This whole project may just be scrapped. I'm worrying about this drivetrain not being reliable. And if I ever get a rear flat, it will be a major pain because I'll have to loosen the motor to pull the chain off.

Edit: rather, I simply didn't line of the sprockets correctly. I think it's because I've been looking at it from and angle (bike leaning against the wall). Once I got it outside I could see it was clearly off. I am spending so much time on this! agh


If I could get a rear disc hub with 130mm spacing I'd be able to do my other design with the reduction and motor above the BB.

Or I may just forget the whole road ebike and continue with my 4th build mtn bike frame with the reduction design.


Update:

This specific design is being discarded, unfortunately. It's next to impossible to mount the motor where I want, there is not enough torsional support. The motor even got warm from a few minutes of < half throttle going up light grades at 10mph. It'd surely overheat with normal riding.(although on this test run I had no bike drivetrain setup, and I would pedal hills normally, it's still way overgeared. I'll post a pic of what I spent about 15 hours on. But this project is out. I will be using the same motor and 80 tooth sprocket on the mtn bike build, using Recumpence's disc brake adaptor on the rear mtn wheel. This 4th build will have an additional reduction, giving the bike proper gearing at 25-40mph top speed depending on which sprocket I use in the back.

Oh well!. Many prototypes fail.... The lesson is: the motor mount MUST be very secure!. duhh

[veloman]

Here's the latest pics.

As I look at it again, I thought I had the alignment right, but it's still off.... I may give it ONE more shot at realigning the drivetrain.

I still have the problem that I can only get a couple hundred watts of power from the motor at 15mph, maybe more at 25.... It's just so overgeared, prob not a good idea.

So i did fix the alignment so that is not a problem anymore. The problem is you can't run this motor with this reduction at 36v. Earlier on I said it had enough torque to accelerate. But it really doesn't at all. I had to do "S's" to keep 13mph up a 1-2% grade (no pedaling).

I think this is the same motor as I had last year. Back then I ran it on 24v and it worked okay with pedaling. This design 'would' work if you ran it on 24v. That is an option....

But I'm putting it on hold so I can build the mtn bike one now.

[flyinmonkie]

veloman,

That looks like the same currie I have. Mine is a 600w. I think they are the same up to 1000w, the 1000w just has cooling fins on the outside. It depends how many volts you run through them as to what you get out of them. I stared with mine on a mt bike at 24v and it needed to be reduced a lot to make it work. Then I ran it on a chopper with a 20in wheel at 36v and it was pretty good, but still needed a lot of reduction. I have been very happy with it so far and am going to put it on a dirt jump bike next, most likely with 44v of lipo. The key is to have either 2 stages of reduction, or a big single stage.

Clay

[veloman]

Clay, you are right. I gave up this design. Below is a pick of the latest build with this road bike. Well, i did more changes to it, but I'm using that geared motor instead, driving the cranks. It climbs hill very well for only a 450w motor, and will have the top end too, since it uses the bikes gearing range. Of course, I can't coast while using the motor.

I am putting that currie on my mtn bike commuter, using a 2 stage reduction, with top speed no load should be about 28-30mph, and it should have great torque with that setup. I am running it at 36 (40.5v off the charger), and once I get it all built up with the watt meter, will see what it pulls with my 30 amp controller. This motor does have big 10ga wires. My 450w geared motor has tiny 14a wires in comparison, so it may indeed be capable of 1000w continuous.

[veloman]

Here's the 'near' final complete bike. I can pedal with no motor drag, but must pedal when the motor is on. It weighs 42lbs with the 36v 11ah pack. I will be putting normal drop bars on the bike. Aero bars with this setup just doesn't feel right or worth it.

It rides okay, just doesn't feel right to me. The great thing about road bikes is the quick handling and fast acceleration and light weight. This build loses all of those great qualities. It's not as much of a 'bike' as I would like. It's still a beast up hills though, with that motor design. However, I'm still faster on my normal road bike for short efforts since I can ride clipless and sprint (1800w me, 20lb bike vs 1200w hybrid power 42lb bike) and dive into corners. The only places this bike really shines is on sustained climbs and strong headwinds, and smooth flats.

If anyone in the Austin area wants to buy it, I'd let it go for $950 with battery pack and charger, or 650 without battery/charger. Total bike weight is just 42lbs. Range would be 30-70miles depending on many factors.

On my next build I'm probably going to go to a very small front hub motor and smaller battery pack, I really need to separate the motor from the pedaling and get the weight down a lot more.