0-30 MPH with bicycle tires

[E-HP]

I've been playing around with an app call GPS Race Timer on and off. There's a section of road at the bottom of the hill with no traffic, at least for a few hundred feet for testing. I usually do a couple of runs when my battery is charged up, then go for a longer ride afterwards.
Besides weight, I'm starting to conclude that traction/tires is a significant limiting factor for acceleration for an ebike when using bicycle tires, even if the bike has power to accelerate quicker. After the tires hook up, power becomes the bigger factor, and where in the curve that power is located.
I'm using this thread to log results of doing small tweaks to see how they affect 0-30MPH times. I'd be interested in how other ebikes perform as well.
I setup the app initially testing 0-20MPH times. The data was fairly consistent, but I felt 0-30MPH would better represent the range I normally ride in. 0-20MPH times were around 2-2.2 seconds, heavily dependent on the launch. 0-30MPH times hover more around 4 seconds, and 200 feet, in my initial tests. I launch the bike the same way I would with a motorcycle, body weight forward, flat in almost a prone position. My head is over the front wheel. My best times happened when I can keep the rear wheel from losing traction, and the front tire is about 6" off the ground for the first 30 feet or so. I think if I could get my weight more forward without losing traction, then more of the power will be used to accelerate the bike forward, but that may be the limitation of bicycle tires. The weight savings would also be a factor.

Here's one of my runs from initial testing:


Bike weight: 82lb
Total weight: 261lb
Motor: Leaf 5T
Controller: 70A, 200A phase
Battery:
20S: 52V28Ah 14S8P 40A/60A peak + 6S lipos
Total voltage under test conditions: 82V
Tires: 24x2.8 @35psi

I plan on trying a couple of things next. The first will be to lower the tire pressure and more weight forward, which should help with traction. The second will be to remove my 52V pack and use all lipos. That may help with voltage sag that I might benefit from in the 20-30MPH range. I'll probably try a couple of 0-20MPH runs under these conditions to see where the benefit shows up most. If others want to participate, posting the summary data of the bike would be helpful.

 

[Eastwood]

Nice, just downloaded the app
I’m all about the acceleration! Driving fast not so much, acceleration/drag racing all for it 8)

Well I would like to contribute but I have motorcycle tires.
I’ll be using this app to see what my 0 to 30 mph runs are. it feels around a couple of seconds but I’ve never timed it. I raced a can am outlander 1000 and A Honda side-by-side 1000cc and they both got smoked from 0 to 30mph. Then after 30 mph they go flying by me :lol:
Then I’ve rode with a few two-stroke 250s and I feel like I accelerate harder but I’ve never actually drag race any. Normally I’m trying to conserve battery out riding trails or Enduro.

When I raced my two buddies on their 1000’s had the controller set to,
170 dc Amps
500 phase amps
Then the mid throttle current was set to 300a

 

[Eastwood]

Also I’m about to switch to a 16” rear rim from a 19”. So it’ll be interesting to see the acceleration time difference.
Well Moto rims.

 

[E-HP]

Apparently my first test was invalid. I'm pretty sure I didn't set my three position switch to high on my earlier run. I tried a single run today when I went out to grab some take out. For this run, I added some lipo packs in parallel with my 52V pack, to eliminate voltage sag (7V > 1.5V sag). This time when launching, I shifted my weight even more forward and only lifted the front wheel right at the start, but was back down within a few feet. I don't think this was enough for the improvement I saw, so my conclusion is that I likely had the controller set to either low or medium on the earlier run. I think the lipos helped more in the 20-30MPH range, since it felt like the bike was pulling a lot harder than last time in the upper range.

Bike weight: 84lb
Total weight: 261lb
Motor: Leaf 5T
Controller: 70A, 200A phase
Battery:
20S: 52V28Ah 14S8P 40A/60A peak in parallel with 3Ah lipos + 24Ah 6S lipos
Total voltage under test conditions: 82.5V
Tires: 24x2.8 @35psi



I'll try lowering tire pressure next.

 

[E-HP]

Well I would like to contribute but I have motorcycle tires.
I’ll be using this app to see what my 0 to 30 mph runs are. it feels around a couple of seconds but I’ve never timed it. I raced a can am outlander 1000 and A Honda side-by-side 1000cc and they both got smoked from 0 to 30mph. Then after 30 mph they go flying by me :lol:

Any data would be interesting to look at. I'm expecting the tires will give you more control of the launch.

 

[DogDipstick]

Hahah I have done the exact same thing.

35H motor, 8.5kV, 50A/100A, back and forth, datalogged, time and again, same spot, trying to get better times. 80lb bike, 262lbs loaded. I'll try to fid the logs and post screenshots here.

My problem is if I use full power on launch you immediately throw the bike twenty feet out from under you and you are on your butt. . So you cannot full throttle until you are moven 10mph+. I did this with a 20kW bike too and that thing was downright dangerous.

I am sure it I strap the fork compressed I could change the weighted distribution to be at least 25% faster.

 

[E-HP]

Hahah I have done the exact same thing.

35H motor, 8.5kV, 50A/100A, back and forth, datalogged, time and again, same spot, trying to get better times. 80lb bike, 262lbs loaded. I'll try to fid the logs and post screenshots here.

My problem is if I use full power on launch you immediately throw the bike twenty feet out from under you and you are on your butt. . So you cannot full throttle until you are moven 10mph+. I did this with a 20kW bike too and that thing was downright dangerous.

I am sure it I strap the fork compressed I could change the weighted distribution to be at least 25% faster.

Ya, it's almost like a fun side hobby from the normal ebike stuff. I've been on other forums for other hobbies and sometimes they make contests for things like this, but not really competing against other, but against their own progress. It mainly turns into sharing tips and information. I may not make it into the 2 second club, but I'm happy moving from the 4's to 3's, in the bicycle hub motor class. :lol: I'm wondering how mid drives would do, since gearing choice and shifting come into play, and still having to manage weight distribution.

I didn't even think about compressing the fork, for instance; which would have been something I could played around with when I was using my Talas fork, with the adjustable travel. Either way, it opens up another train of thought around weight distribution, besides just leaning forward. :thumb:

EDIT 2-11-22 - I forgot to check when I tested, but fortunately I didn't reset my CA, so I could check my peak Amps from adding the parallel lipos to my 52V pack. The highest peak amps I've seen before, without the helper packs was 109.9A. After adding them, my peak amps hit 118.9A, so I'm sure that contributed to the improvement I saw. That's 70% higher than the controller's rated current, so it's performing a good bit above specs, and just short of 10kW.

 

[Eastwood]

Any data would be interesting to look at. I'm expecting the tires will give you more control of the launch.

Actually the opposite right now because I have knobby tires lol
The first time I raced my buddy on the side-by-side my back tire spun the entire way until 30 mph. I was fishtailing down the street but didn’t let off the throttle :wink:
The second time we raced I didn’t lean forward as much and I was able to keep traction.

I miss my Shinko 241s but I use this bike for Enduro so I have to keep knobby tires. Well I guess it’s better for me to drag race in the dirt then lol

The Shinko 241 is on the left. My current tire is a Michelin star cross 5 soft.

 

[Eastwood]

So plan on testing this app today with my new super Moto wheel, QS205. I’ve tried this app briefly before but when I launch/Holeshot the app doesn’t start, am I my missing something here? Doesn’t the app start when you accelerate? I’m curious to see what the acceleration time is as my overall tire diameter is 21 inches, 16” Moto rim.

 

[E-HP]

So plan on testing this app today with my new super Moto wheel, QS205. I’ve tried this app briefly before but when I launch/Holeshot the app doesn’t start, am I my missing something here? Doesn’t the app start when you accelerate? I’m curious to see what the acceleration time is as my overall tire diameter is 21 inches, 16” Moto rim.

I noticed that it needs a good signal to work properly. It wasn't reliable if I had my phone in my pocket, but if it was mounted on the holder on my bike, it starts as soon as the bike moves. I haven't tested the accuracy, but maybe I'll see how it works in my car compared to a stop watch.

 

[Eastwood]

So plan on testing this app today with my new super Moto wheel, QS205. I’ve tried this app briefly before but when I launch/Holeshot the app doesn’t start, am I my missing something here? Doesn’t the app start when you accelerate? I’m curious to see what the acceleration time is as my overall tire diameter is 21 inches, 16” Moto rim.

I noticed that it needs a good signal to work properly. It wasn't reliable if I had my phone in my pocket, but if it was mounted on the holder on my bike, it starts as soon as the bike moves. I haven't tested the accuracy, but maybe I'll see how it works in my car compared to a stop watch.

OK thanks, I’ll try again with the phone on the handlebars. My signal must’ve been low the first time because it wouldn’t activate when I started so I just gave up. Then I was dealing with my rusted hub motor so I haven’t had an opportunity to test. I’m actually out riding now but stoped and found a spot to do a quick charge. Found a school to charge up 8)
Bungee corded my charger to the back of my enduro seat :lol:

 

[Eastwood]

84v
Dc amps 180
Phase amps 500
Bike weight around 170lbs
Rider weight around the same 175-ish
Battery 2x 20s 8p - so Basically the two batteries = 20s 16p
QS 205 V3 5.5T
Rear tire: 90/80 16” Shinko moped tire. OD = 21”
Voltage sag = horrible - around 6V :lol:

Once I put back together my new QS205 V3ti 6T Will do this test again as the 6T pulls a little bit harder than my older 5.5T. Allowing the varnish to dry before reassemble. That motor has the same size rim but an off-road tire which is a little taller.

 

[E-HP]

84v
Dc amps 180
Phase amps 500
Bike weight around 170lbs
Rider weight around the same 175-ish
Battery 2x 20s 8p - so Basically the two batteries = 20s 16p
QS 205 V3 5.5T
Rear tire: 90/80 16” Shinko moped tire. OD = 21”
Voltage sag = horrible - around 6V :lol:

Once I put back together my new QS205 V3ti 6T Will do this test again as the 6T pulls a little bit harder than my older 5.5T. Allowing the varnish to dry before reassemble. That motor has the same size rim but an off-road tire which is a little taller.

Nice!! Did you get any wheel spin or wheelies during the launch?

 

[DogDipstick]

My new build V3 4T is registering right around 5 sec to 40mph right now. 4.5kW contin and 150A phase peak. Pulls a solid 105A for a short timed speed test from the batt.... Likes to sit right around there.... However this Kelly is doing its thing. Yea the tork from the lower count wind is hurts a little... It has slightly less tq off the line than my 6T 35H V1 motor did...That thing was wild till it blew up... But this 4T heavy motor really torks right past that. A steady solid 5 sec to 40mph. Its faster than my little motor was for sure. It just pulls and pulls on the top end,. Any speed you go, you are instantly a half a twist away from what kinda feels like Hyperbike-style acceleration ( its not though, just my imagination probably, but it does rip from 30-50mph.... )

 

[Eastwood]

Nice!! Did you get any wheel spin or wheelies during the launch?

No wheel spin but the front wheel lifted. Was hanging over the handlebars with my chest Close to the bars, my head was over the front wheel :lol:

It also helps keep the front wheel down that I have a 280 mm rear shock so the back of the bike is tilted up slightly more. Tire pressure was at 14 psi

My next battery will have a 250amp bms limit so I’m really curious to see how it performs. Been looking at cells recently as this will be my first build. Leaning toward 22 S 18p, 54 amp hours.
Massive battery for my first build lol. Definitely could use your guys input with my first battery build. Hopefully I can get through the summer with my UPP batteries in parallel.

 

[Eastwood]

My new build V3 4T

Interesting, I always wondered the performance of the 4T. Seems like the best option for commuting purposes because you still have decent torque and good top speed. The top speed of my 5.5 and 6T sucks lol. The 6T is around 40mph @ 72v nominal. That’s why I’m looking at building a 22s to bring up the top speed slightly.
45 mph-ish or 50 mph would be nice.

 

[jimmyhackers]

tyre pressure is a big thing. always check your tyre pressure regularily (rubber is porous and lets air escape regardless)

i like to run at a highish pressure, 50psi. less tyre wall flex...less likely to damage your rim or pinch a tube from pot holes, less power sapped.

its your suspension that should really be handling grip (downwards force of wheel onto the road)
this in conjucntion with tyre compound (how soft the rubber is) and somewhat tread pattern (more so offroad/wet conditions).

low tyre pressure may get you more grip off the line.....but its compromise is reduced performance everywhere else and a potential durability/saftey issues.