Fun and cheap EV racing series open to everyone

[amberwolf]

I just discovered electrathon today while looking at velomobile & fairing ideas for a custom build. I'm curious if THIS could be altered slightly to use in what I want to build.

Since we don't know what you want to build, we couldn't really say.

I would recommend starting a thread in the "builds" section and providing as much info as you possibly can about it.

Front axle & steering are the only parts of this build I'm not experienced with. I've built bikes, e-bikes from conversion kits, and can weld. $250 (plus $30 for shipping) is enticing to have that problem solved. But it says it's set up to run 14" wheels and geometry is based on 55" wheelbase. Also I can't tell from the pics if I'd be able to pedal without banging my knees on the steering assembly. I wish there were more pics and info such as weight.

I'm also wondering why the velomobile and electrathon builds are so different in the areas of wheel size and chain gauge? Seems all the electrathon builds are running smaller and thicker wheels with heavier duty chains vs the standard bicycle wheels and bicycle chains of velomobiles. I assumed they'd both want to reduce weight in those areas.

 

[CMo44]

Since we don't know what you want to build, we couldn't really say.

I would recommend starting a thread in the "builds" section and providing as much info as you possibly can about it.

Yes, and I already got a quick answer from Steve who builds them and runs that site. Seems they are heavy (36" of 14 gauge 1.5" steel tubing) and there will be knee clearance issues from pedaling between the bottom and the steering controls + plate.

But I'll start a build thread once I'm closer to beginning the project. Thanks!

 

[amberwolf]

Sure. My point was really that you can't ask questions of people and expect a useful answer without providing them sufficiently complete information.

 

[ProEV]

I'm also wondering why the velomobile and electrathon builds are so different in the areas of wheel size and chain gauge? Seems all the electrathon builds are running smaller and thicker wheels with heavier duty chains vs the standard bicycle wheels and bicycle chains of velomobiles. I assumed they'd both want to reduce weight in those areas.

All things being equal:

1 A wider tire has less rolling resistance (which is pretty counter intuitive)

2 A bigger wheel has less rolling resistance.

3 A tire with thinner rubber has less rolling resistance.

4 A tire running a higher air pressure has less rolling resistance.

5 The more frontal area the tire has, the more aero drag.

Choosing the right tire is trying to find the best compromise of these guidelines.

I do not know what works for velomobile but here is some of our thinking in Electrathon.

The Maxxis Hookworm 20" is popular in Electrathon. It's max pressure is 120 PSI, so it is possible to run high pressure. It is a little over 2 inches wide. We switched to the 16" and saved 16 square inches of frontal area. This cost us in guideline 2 but gained in 5. This should benefit in higher speed tracks where aero is a bigger influence. Of course, Maxxis suddenly dropped making 16" Hookworms

Electrathon involves a lot of cornering, so smaller wheels flex less. Wider tires grip more. Our tires probably wear more which means thicker rubber.

The ProEV Super Coupe came with bicycle chain but it was not up to the strain of the torque loads including reverse loads from regen. We run a #219 chain, rather than #35 Go Kart chain because we need a higher ratio to get the motor to the RPM it is happiest in.

Cliff

www.ProEV.com

 

[CMo44]

All things being equal:

1 A wider tire has less rolling resistance (which is pretty counter intuitive)

2 A bigger wheel has less rolling resistance.

3 A tire with thinner rubber has less rolling resistance.

4 A tire running a higher air pressure has less rolling resistance.

5 The more frontal area the tire has, the more aero drag.

Choosing the right tire is trying to find the best compromise of these guidelines.

I do not know what works for velomobile but here is some of our thinking in Electrathon.

The Maxxis Hookworm 20" is popular in Electrathon. It's max pressure is 120 PSI, so it is possible to run high pressure. It is a little over 2 inches wide. We switched to the 16" and saved 16 square inches of frontal area. This cost us in guideline 2 but gained in 5. This should benefit in higher speed tracks where aero is a bigger influence. Of course, Maxxis suddenly dropped making 16" Hookworms

Electrathon involves a lot of cornering, so smaller wheels flex less. Wider tires grip more. Our tires probably wear more which means thicker rubber.

The ProEV Super Coupe came with bicycle chain but it was not up to the strain of the torque loads including reverse loads from regen. We run a #219 chain, rather than #35 Go Kart chain because we need a higher ratio to get the motor to the RPM it is happiest in.

Cliff

www.ProEV.com

Damn! Thanks for all the info. You answered my questions for sure. I figured it was mostly due to cornering forces but didn't know how hard they were since velos and electrathon were doing the same speeds generally. But racing vs a gradual turn (or even a 90 deg turn at an intersection) is way different force wise.

I am surprised how a wider tire has less rolling resistance. I was under the opposite impression with road bike tires being skinny vs thicker mountain bike ones. I associate the speed benefits from not only the faster gearing of a road bike but the less friction with the road from less rubber touching it.

My only question from what you explained is, what does this part mean?

"This cost us in guideline 2 but gained in 5."

How are you calculating that specifically? I know its a relationship between weight, power, and friction (w/road and air), but where are you getting the 2 and 5 from?

Thanks!

 

[Hillhater]

I am surprised how a wider tire has less rolling resistance.

Over to you: What's the optimal road bike tire width?

Does wider rubber make everything better?

www.bikeradar.com

For years, the standard road bike tire size was 23mm. Thin, light and able to be pumped up to back-achingly high pressures, there was no need to experiment. Then science, endurance events, and gravel riding got in the mix.
Science has now proven that wider tires actually have less rolling resistance than skinnier tires. Wider road tires provide a more forgiving ride and improve handling through a, you guessed it, wider contact patch that makes endurance riding safer, easier, and more accessible. Finally, gravel riding popularity brought on wider tires and the associated equipment to mute the bumps, take on the rocks, and provide some traction in the loose, dirt road conditions.

Now even Pro Tour teams are rolling on 25mm and even wider rubber depending on the race or stage. And rim manufacturers are adapting with wider rims and unique profiles that make bigger tires even more aerodynamic. Bike companies have taken note by allowing a bit more room between the stays to accommodate larger tire widths.

 

[ProEV]

My only question from what you explained is, what does this part mean?

"This cost us in guideline 2 but gained in 5."

How are you calculating that specifically? I know its a relationship between weight, power, and friction (w/road and air), but where are you getting the 2 and 5 from?

Thanks!

2 A bigger wheel has less rolling resistance.
and
5 The more frontal area the tire has, the more aero drag.

I should have used a better term then "a bigger wheel". "A larger diameter (taller) tire has less rolling resistance" is more accurate. So I am saying that running a smaller tire increases rolling resistance (cost in 2) but decreases aero drag (gains in 5).

If I understand rolling resistance correctly, geometry plays a big roll. Most (all?) of rolling resistance is the energy required to deform and reform the tire to create the contact patch. The contact patch is where the round tire becomes flat to match the road surface.

The thicker the rubber, the more energy required to deform it. The higher the air pressure, the smaller the contact patch and the less the tire deforms, so less energy required. The larger diameter (taller) tire advantage is geometry. The larger the diameter, the closer the arc of the tire matches the flat line of the road, so the less deformation required to form a flat section.

The wide tire advantage is due to geometry as well. A skinny tire and a wide tire of the same size, with everything else being equal, will have the same size contact patch. The shape of the skinny tires contact patch will be a long and skinny oval. The wide tire will make a short and fat oval. Because of the arc of the tire, the middle part of the long and skinny oval will have to move a greater vertical distance requiring more energy than the smaller movement of the middle of the short fat oval.

Cliff

www.ProEV.com

 

[CMo44]

2 A bigger wheel has less rolling resistance.
and
5 The more frontal area the tire has, the more aero drag.

I should have used a better term then "a bigger wheel". "A larger diameter (taller) tire has less rolling resistance" is more accurate. So I am saying that running a smaller tire increases rolling resistance (cost in 2) but decreases aero drag (gains in 5).

If I understand rolling resistance correctly, geometry plays a big roll. Most (all?) of rolling resistance is the energy required to deform and reform the tire to create the contact patch. The contact patch is where the round tire becomes flat to match the road surface.

The thicker the rubber, the more energy required to deform it. The higher the air pressure, the smaller the contact patch and the less the tire deforms, so less energy required. The larger diameter (taller) tire advantage is geometry. The larger the diameter, the closer the arc of the tire matches the flat line of the road, so the less deformation required to form a flat section.

The wide tire advantage is due to geometry as well. A skinny tire and a wide tire of the same size, with everything else being equal, will have the same size contact patch. The shape of the skinny tires contact patch will be a long and skinny oval. The wide tire will make a short and fat oval. Because of the arc of the tire, the middle part of the long and skinny oval will have to move a greater vertical distance requiring more energy than the smaller movement of the middle of the short fat oval.

Cliff

www.ProEV.com

WOW! Thanks for the very detailed reply. I really appreciate it!