How handlebar Battery bag/rack effects handling??

[RLT]

OK, it is obvious, even to me, that putting weight up front, whether it be batteries or motors is going to make handling noticeably worse.

And I'm doing both, so even worser worse

I my first attempt on the 2WD bike I had 11 pounds of batteries in a regular handlebar bag, and it wasn't too bad, but I'm thinking for piece of mind, and because the new battery packs are going to weigh about 15 pounds each, I'm going to build a front rack to support the bag.

Here's the question: Which do you think would be better for handling and general ride;
Having the rack mounted to the handlebars and fork crown (above the suspension stuff) so it turns when the handlebars turn, or mount it solid to the frame/ head tube so it doesn't swing around when the handle bars move?

I'm guessing that if it turns with the handlebars, it will tend to cause the equivalent of oversteer, (or maybe understeer at first, then oversteer once centrifugal (centripedal?) force catches up)

And mounted on the frame, it would cause something like understeer....

Since either way, it is going to require welding, I'd rather not have to experiment.... Which way would be better overall?

Thanks in advance for your thoughts.

 

[lawsonuw]

I would recommend attaching the batteries to the frame and head tube. One of the LBS's has a cargo bike with a large frame mounted basket over the front wheel and I think it's a great idea.

One of my previous projects involved rebuilding the front suspension of a RC motorcycle. I did a lot of reading on bicycle self stability for that. http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics Is a good summary of what I was able to find. My opinion is that mass low and forward produces the best self stability. If mass has to be mounted high up, mounting it over the front wheel is better than over the rear because less steering input is needed to maintain balance. (Wiki agrees with me http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics#Center_of_mass_location 8) )

My thoughts on handlebar/frame mounts is that a handlebar mount will make the steering heavier for no good reason.

Marty

 

[Dr. Shock]

I'd think about making a rack that allows battery mounting in front panniers, as low as possible.

I had two 17Ah lead acids mounted in my handlebar rack on an early test rig, and the bike was almost impossible to steer. I replaced these with a couple of dewalts in the same location and it wasn't bad, so I'm guessing 11 lbs is enough where you'd notice some effect on the steering, but it wouldn't be impossible. It would work a lot better if you put the batteries low, near the axle.

Here are some custom racks that might give you ideas:

http://antbikemike.com/basketsandracks.html

http://www.ahearnecycles.com/pages/karetouring.html

http://www.vanillabicycles.com/

 

[Toorbough ULL-Zeveigh]

When you go to AntBike, whatever you do don't let the salesman talk you into getting a Rear Woody.
Insist upon the French Rear#3.
cest bonne!

Why do you think prices start at $250?
You're paying for the service.



I'd like to try hanging some batts off this Tubus or making something similar.
I figure it would have the least impact on handling of anything.
It's reasonably low while remaining suspen-ended.

 

[swade]

Check out these racks for front paniers:
http://www.oldmanmountain.com/Pages/RackPages/FrontRacks.html

 

[Mathurin]

Well, I've had one bike that felt better with a handlebar bag then without... Maybe try it out with duct tape & something that approximates the weight or something, you may like it.

 

[RLT]

Thanks for the input so far guys.

I'm afraid that panniers are out... Sure, balance would be better, and higher carrying capacity, but I have some sort of psychological defect that makes me think that they will cause more trouble than good, off-road, with bushes, rocks and rabid squirrels hitting them and knocking me off balance . If this were to be a road bike, I'd probably be more receptive to the idea.

Don't worry about some salesman talking me into something... Whatever I do, is going to be home made... But the various links you have provide give me some more design ideas.

The info Lawson provided was great... (Even though I didn't understand 3/4 of it ) Kind of reinforced my gut feelings.

Looks like I'm going to have to learn to MIG aluminum... (The frame and head tube are Al) ....I have the equipment and materials but I don't think I've ever even had the Al spool on the welder, much less pulling the trigger on it. Although I guess I could bolt it....Use some adhesive backed fender washers, and maybe the bolt holes won't tear when I hit a bump.

 

[lazarus2405]

centrifugal (centripedal?) force

Angular momentum is the term you're looking for.

Also, thanks for that link (http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics). That's some really nice information.