John in CR's quest for 82mph

[cell_man]

Be careful with all that power on the front wheel. I'm only running just over 2KW per motor on my dual motor bike and it lights up the front so easy at fairly low speeds. Easy to lose the front when coming out of a bend. Maybe I'll reduce the current limit on that front motors controllers a bit.

 

[John in CR]

Thanks Cell-man, I do plan on taking it very easy learning how 2wd handles on 2 wheels. I will run both lower torque and lower power on the front. I'm treating it more as an experiment than a permanent bike. One of the builds in queue will be extra long, probably > 2 meter wheelbase. That one will definitely get 2wd, which I believe will increase safety by pulling the front around, but that will be a lower powered speed restricted rig.

 

[mwkeefer]

I can't say with some confidence that an electric bike will definitely surpass the 81mph human powered speed record with me aboard, and I won't have to get inside a lima bean on 2 wheels to do it either. My secret weapons are in route, 12 fet and 18 fet Lyen controllers with 150v fets.

So the world record for a human powered cycle is 81mph - I am assuming that's full fairing and with an 80lb rider?

How close to the 82mph (or 81.1 i suppose) have you been? I consider myself nutz and I have tons of power systems here which could deliver 100+v and maybe even get close to 80mph in the right combination but my lord I wouldn't want to... I have done 40 downhill on an eBike and 38mph on a flat but that's freaking scary!

Can't wait to see this one posted.

-Mike

 

[John in CR]

Mike,
My first couple of ebikes were just regular uprights with a motor, and yes above 30mph was scary. The past year I've been using these 2 that are lowered with stretched wheelbases, so they feel better at speed.

Luke got the red/black one up to 63mph or so, and I've had the blue up to 60mph on the highway. That was at 74v nominal. The blue one is rock steady at that speed, but I can't get visions of that cheap bike tire shredding at high speed. Plus I use it daily for errands and taking the kids to school, so I don't want to take it out of service for high speed upgrades. I have 5 of those motors anyway, so I need to build bikes for the other 3.

One will be a 2wd to get more speed using brute force at 2 hub motors. The other build in process will be low and sleek with a hub motor on the swingarm, but out of the wheel for multiple gearing. With it I'm paying more attention to weigh and aero. Today I picked up a 18" motorcycle wheel with a drum brake for the front of that bike, and the rear will have a Nexus 3 geared hub in a 20" rim and 16" motorcycle tire. Tomorrow I'm going to meet Harold_in_CR, to pick up some 20" diameter balsa logs and talk wind turbines and EVs. The balsa is to make battery covers, partial fairings, and tailbox for storage and aero.

Once the bikes prove stable and feel solid, then I'll take them out on the highway and see what they'll do.

John

 

[cell_man]

I think getting more weight over the front wheel will help traction. My bike is just a typical cheap dual suspension bike so the weight is very much biased to the rear. When you hit the throttle from low speed the front seems to have even less weight on it. If you can get a more even weight distribution (including rider) that will help the traction on the front a lot IMO. When I want to make a quick getaway from low speed I will lean right over the front and it just grips and goes.

Maybe you could have a little switch or push button to only power up (or maybe give it 100% instead of say 30, 40 or 50% when not pushed) the front when you need or want it. I'd be much happier if I could hit the throttle a bit sooner coming out of a bend without worrying about the front washing out on me. Maybe a potential divider on the throttle feed to the front motor which could be switched out when you wanted to, would work well. Should be pretty easy to implement I reckon. I'll have to try doing it myself sometime.

 

[TMaster]

Its been a while for this thread, but I was watching History channel a few days ago and there was this 2 wheel drive off road motor bike, and they said the front wheel had to turn just a little bit faster then the rear because on turns the front wheel would slip out if it wasn't. The top speed was like 15-20mph on this bike.

 

[dogman dan]

That may explain why I don't seem to have any problem at all, pulling 3000 watts out of corners with a front motor. Maybe if I had a rear on it pushing harder it would be different.

Seems like it oughta work ok to have the front hub pull 40 amps and the rear 30. Gotta use two controllers anyway right?

BTW, that 81 mph human powered record was done drafting a vehicle with a special tail fairing. So zero wind drag.

 

[GTR2EBIKE]

That may explain why I don't seem to have any problem at all, pulling 3000 watts out of corners with a front motor. Maybe if I had a rear on it pushing harder it would be different.

Seems like it oughta work ok to have the front hub pull 40 amps and the rear 30. Gotta use two controllers anyway right?

BTW, that 81 mph human powered record was done drafting a vehicle with a special tail fairing. So zero wind drag.

Drafting doesn't equate to zero drag, if it's larger than air and moves it has drag. I watched the video, I didn't see a car in front of it.

 

[dogman dan]

I must be thinking of a different world record. I was remembering one where they had a huge fairing, like 8x8, sucking the pedaler along. Rider was on a normal racing bike except for the pizza pan front sprocket.

No drafting vehicle then? impressive!

 

[liveforphysics]

This is the current bicycle speed record holder:

166.9mph. That's clipping along pretty good for a bicycle, even for a bicycle following a dragster with a draft-box.


http://www.fredrompelberg.com/en/html/algemeen/fredrompelberg/record.asp#aG26C332104Q524CX1B5Q

 

[beast775]

holy crap! i can just imagine the crank speed.wow.

 

[liveforphysics]

holy crap! i can just imagine the crank speed.wow.

166.9mph = 14,690feet/min

20" tire OD = 5.23ft/rev

2,808 wheel speed.

If I had to take a wild guess from looking at the related sprocket sizes, I would say it's maybe a 1:6 feeding a 1:5, so a 1:30 combined.

Which would mean a crank speed of: ~93rpm

 

[dogman dan]

Goes to show a stretched frame is stable.

 

[sk8norcal]

So the world record for a human powered cycle is 81mph - I am assuming that's full fairing and with an 80lb rider?

Sam Whittingham is fairly short and compact but not 80lb...
135lb would be my guess...

http://www.youtube.com/watch?v=wuUmmN3c0dw

82.33 is the current record.
http://www.ihpva.org/hpvarec3.htm#nom01



here's another team attempting the land speed record (drafting)
http://www.teammccallusa.com/press/

 

[dogman dan]

Awesome vids.

 

[sk8norcal]

dogman, did you see that one guy was going backwards?

 

[Anonymous]

John... don't let anything slow you down mate, keep building it till it's complete, if someone said tankslap, then reinforce it how you best see fit but whatever you o, keep building it till you're done, and also, give us an acceleration / drive-by / velocity video

Thanks Cell-man, I do plan on taking it very easy learning how 2wd handles on 2 wheels. I will run both lower torque and lower power on the front. I'm treating it more as an experiment than a permanent bike. One of the builds in queue will be extra long, probably > 2 meter wheelbase. That one will definitely get 2wd, which I believe will increase safety by pulling the front around, but that will be a lower powered speed restricted rig.

 

[John in CR]

No worries NovemberSierra, I'm not concerned in the least of tank slap. That's generally a concern when you've got a sporty handling geometry that is close to an unstability. Then when the geometry changes during compression of the suspension, it gets pushed into the realm of instability. I plan to stay at the stable geometry end of the spectrum even at the limits of the suspension.

As far as shooting for top speed, I'm going to give it a go first with my cargo bike first with a single motor. I don't want to hear any whining from above the US's northern border. The delay have resulted from a bear of a rainy season this year, and the fact that I'm just not all that motivated for high speed. The weather's begun to break though, so my excuses have about run out.

When I do will have both video and gps evidence. I think a more interesting though video might come from the little race bike I built and take it out in traffic to demonstrate just how much faster it is than a car from point A to point B. That's a lot more fun to me than WOT out on the highway with very little traffic. 8)

John