LocostUSA.com

$60 a pop but. ..http://www.chubbyscruisers.com/shop/schwinn-style-springer-fork-p-198.html

Oh man whatever you do do NOT use a springer fork. They are notoriously flexy and not very strong. You would be far better served by using some more or less standard mountain bike forks. With most of them you can adjust preload (and sometimes damping) AND you get a place to run either rim or disc brakes.

Hey if you want to be really fancy (and poor) you can go full circle and get Cannondale 'Lefty' shocks+wheels

I would strongly advise you NOT to use bicycle wheels.

Bike wheels are not designed to take any lateral loads as bikes always lean into the corners and the loading is always in the plane of the wheel. I think the first time you do a hard corner, even at under 30 mph, the tire will roll off the rim or the spokes will pull out or break.

I also wonder about using EMT tubing for the chassis. Besides the zinc fumes issue, I doubt that it is as strong as same size ERW steel tubing. It's only meant to support the weight of wires over 5 ft spans. I think you'll find that ERW tube is cheaper too.

Goggle tadpole trikes before condeming all bicycle wheels for trike / lateral load use.

Im thinking about cutting my losses and trying the thing with no front suspension. That way, I minimize the remaining time and money spent on the project, and I will be able to see if the wheels/EMT bend and break. If they break, I can modify the design, and if they don't, I can add front and rear suspension later.

They all seem to have wheels with extra wide hubs, more spokes, etc. In other words, designed to take some side loading.
Also, they are carrying just a driver and not three hundred extra pounds of motor, batteries, etc.

Regular bicycle wheels are designed to safely carry a vertical load of maybe 250 to 300 pounds on two wheels. That's about 150 pounds each. Assuming they have a 300% safety factor to allow for bumps and other impact loads, that would mean they would fail at around 600 pounds - vertical load. This load is shared by many spokes in tension or compression.
When you apply a lateral load, the load is shared by only very few spokes and because of the angle of the spokes to a rather narrow hub, I would guess that failure would occur and around 10% or 60 pounds. 0.15g for a 400 pound vehicle.

Easy enough to verify. Take a wheel and lay it flat on the ground on its hub. Then stand on the rim with feet at 9 oclock and 3 oclock.

I built an electric horseless carriage a few years ago. http://www.szott.com/carriage/carriage.html
It uses heavy duty Worksman wheels http://worksmancycles.com/shopsite_sc/store/html/movers.html
Even with those wheels, people that have built similar vehicles have experienced wheel failure on hard cornering.
And these things only do about 15 mph tops.

A wheel failure at speed while surrounded by 200 pounds of lead acid batteries would not be fun.

I don't want to discourage anyone from building his dream car but please be safe.

I've worked as an engineer in the bicycle industry for over 20 years and can confirm that your numbers are pretty close to what sort of maximum loads we design for. I have validated wheels for larger-than-normal loads but, as you say, these are vertical loads. Regardless, I can at least pass along some tips of what makes a stronger wheel. Certainly higher spoke counts help but so does higher (and UNIFORM) spoke tension, higher spoke quality (such as DT Swiss Stainless steel), higher (thicker) spoke gauge and the use of thread locking compound or locking nipples. A radial lacing pattern would probably provide better bracing for lateral loads although it is not as good at transmitting braking loads.

The 1"-tall tires are being asked to act like 3-4" tall car tires both in cornering and hitting bumps, but aren't able to offer anywhere near the cushioning that car tires do. It can work, but only at low speeds and/or perfectly smooth road surfaces.

I understand and agree for the most part.

My point is that not all bicycle wheels are equal in strength.

Bicycle wheels have been used on trikes with success at over 30 mph.

A smaller diameter wheel with the same hub and spoke guage and count will have more lateral load strength due to the change in spoke angle relative to the load.

A few degrees of camber help too.

An electric drive system for a bicycle or trike to drive around the nieghborhood does not need to weigh more than 100 lbs, batteries included.

I'm familiar with the industrial trikes in the link. I used one regularly when I worked for an airline, loaded with tools. With one wheel in front, not much cornering force can be generated (massive understeer) but the front tire never came off the rim; it just slides.

He has been warned plenty, so let him build it anyway.

Alright, I'm trying to figure out how to proceed without ignoring all of your warnings, which I know are wellfounded. If I place the batteries on either side of the rear wheel, the front wheels will only see about 60 lbs each. Would this, combined with suspension in the rear and standard BMX forks in the front be a viable solution? This would mean no front suspension, but most of the weight would be suspended by the rear wheel. This might bring up issues in the strength of the rear wheel then, as it would see nearly 450 lbs.

Also, I did stand on the wheels while they were on their sides, as Thumper suggested, and they showed no signs of weakness, but I may not have done it correctly.

Thanks for the continual support, I really do appreciate it.

Personally, and I have no data to back this up - it's just a hunch, I reckon *good* BMX wheels will hold up OK. Some of the tricks they do on BMX's involve high impact, and not necessarily vertical, loads.
Just an opinion though so basically useless lol. Sorry

Hey, Nate. First time I've looked at this thread. Great stuff!

One thing that you haven't shared with us is your goal for the trike. We can assume certain things, but better to have you state them. Is this an econobox? Cool toy? Daily commuter? Masters thesis? Seed of your future fortunes?

What do you want to DO with this bike?

I should wait for your reply, but I'm in a typing mood.

Google for "Nacho Libre motorcycle" or similar. I got on a kick to replicate Nacho Libre's trike for a while and found 2-3 builders online who shared their insight. A lot of focus on the front wheels. That bike (apparently a common cargo bicycle in less fuel-addicted countries, such as Mexico) has outboard axle support, which HUGELY reduces load on the axle.

Why such a big back tire? Seems like gross overkill. I'm no engineer, but I don't see your current rear suspension keeping that wheel true, even with the square profile.

As for the things you are discounting and second-guessing... I wouldn't worry about it. You are NOT going to get this thing right the first time, I promise you that. You've come so far, and clearly done some research (though probably not enough), I'd stick with it. Get the thing rolling, put on a helmet, boots, and gloves. Get someone to push you around the neighborhood all weekend. Make some turns, hit pot holes, take some tumbles and put band-aids on your sore spots. You'll probably break some things (hopefully on the bike, not you!). Cut those parts off and build 'em better.

When you get to the point that you can't hardly break it any more, add in some ballast to simulate batteries, motors, and such. Now get TWO people to push you around. Maybe go pedal-power in the next iteration to help sort out the drivetrain issues.

At this point, if you're still with it, you can buy the expensive bits and have a reasonable level of confidence to move forward with it. You might add those to your evolutionary prototype, or it might be worth building the next frame anew, carrying over certain components from the frankentrike.

BTW, if you do this, you'll die, and you can't sue me for talking you into doing dumb stuff. So there.

-dave

What are you doing for caster control on the front wheels?

It's still appreciated.



Thanks! This trike is intended to just scoot around town, most of the trips being only 4 miles per day or so, but I'd also like it to be fun. I want to be able to go 35 mph, and a bit of quick acceleration and sharp handling would be a definite plus. However it is mainly a learning project. I want to build a full size car someday, but I have absolutely no automotive experience coming into this and very little fabricating experience, so this is where I am learning all the basics.



The problem I see with the Nacho Libre trike is the lack of Ackermann. It seems like at speeds higher than 5 mph or so, it would be very tippy in corners. As for the back tire, it is holding up much more weight than the front, and it is having to take all of the torque of the electric motor. If I go through with putting the batteries on either side of this wheel, I even think it may not be strong enough. My suspension may need to be rethought though



I feel like this is has not been stated clearly, but the bullet has already been bitten- I do have the "expensive bits" already, and they are quite heavy. My drive system has a total weight of about 275 lbs. Before your recoil in indignation, this is not the 12Ah 36v system commonly found on electric bikes. I have 48v and 115Ah at my disposal. At max acceleration, I can draw 12kW, once my controller is reprogrammed that is, and can roll at 20mph for over 150 miles, if my calculations are correct. While I now realize that this is overkill, I think it will definitely be interesting to see the results.