Xanda2260 wrote:Wobbling is likely frame flex. Shifting the cog forward and down will likely help, but you may find the frame needs stiffening some.
Really looking forward to pics of this event (if you have time of course).
heathyoung wrote:Nice - the battery limitations were severe this year weren't they?! No fun chemistry.
I was prepping a bike for it this year, but had a bad accident that stopped me from completing it (and competing). I got around the battery limitations using those 20AH A123's and a DC:DC converter in the home-made controller to get maximum energy density out of them - it just fit the price and weight limit. But I never got to try it out
Couldn't even take the Vectrix VX1 for display either this year (sulk).
John in CR wrote:Jman,
It looks when you stretched the wheelbase that it may have decreased the trail a bit on a bike with not a lot of trail to begin with. I had exactly the same problem with my cargo bike, and it got worse as I tucked down for better aerodynamics. You need to increase the trail to get more stability at speed. From you pic, I looks to me like you have only about 1-1.5" of trail. How to change that at this late stage is the problem. I hacked my headset off and welded it back with more slack head tube angle. If yours is AL, that's not an option, so you have to get the tire's contact patch to trail the straight line looking down the head tube by more than it does now by some other method. It's a smaller wheel on the back that would help, though I don't think that's really enough without going too small due to the fairly long wheelbase.
To verify that more trail would make a difference, loosen the headset and turn that front wheel backward if there's clearance with the frame. That will give you more trail than you need, but taking it for a spin that way would demonstrate the difference in stablitiy at speed. It would just be very sluggish at slow speed with that much trail. You could easily find another fork in time that has less offset, which will give you more trail. If the one you have is steel, you may even be able to bend it straighter.
You definitely want stability at speed, so then you can shorten the handlebars for better aerodynamics, and wobbling will hurt efficiency. Are you allowed to pedal? If not then get rid of anything you can, chain derailleur, etc.
John in CR wrote:Yeah, I missed that was last year's bike. This one is looking much more slippery through the air, so I hope you cure your wobble. You don't want it to turn into a tank slapper.
Good luck with the competition!
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