I had a great time, thanks to Mitch's last minute suggestion that I enter. (I'll twist his arm to join this forum!) Thanks for creating this wonderful event!
Okay--time to start thinking about next year.
I'd planned to send you an email, but it may be more productive to open up my notions to public discussion here. Please PM or email me if you wish to take any discussion offline.
I'd like to reference a few race rules and race information here:
> One last thing, in accordance to the agreement stipulated on the insurance, we will also be limiting the motors used > to conform to a 750 watt continuous power rating that should be visibly marked on the motor casing, no switchero of > stickers folks. Too many of us know what to look out for. The 750 watt limit is to Ã¢â‚¬Å“honorÃ¢â‚¬Â the Fed output limit
> and will showcase to the public what amazing things can be done with that amount of assist. Of course you
> can certainly use a less powerful motor, it could be an advantage!
ItÃ¢â‚¬â„¢s inconsistent to Ã¢â‚¬Å“honorÃ¢â‚¬Â the federal 750 watt manufacturer limit while not honoring the federal 20 mph limit. I think that Mitch, by mistake, was the only entrant honoring either limit. I think we should just forget about the limits--at least in an explicit sense. As the classes are defined, the energy allotment vs. distance constraints of each class already serve to limit the riderÃ¢â‚¬â„¢s usable power while remaining competitive. For example, in order to complete the 40 mile race, I had to throttle back to something around 500 watts. I recommend changing both the rules and the rationale for the rules to something like this:
Ã¢â‚¬Å“The energy and race distance, as specified for each class, is designed to preclude average electrical power output in excess of the U.S. Federal ebike manufacturing law limit of 750 watts, i.e., the rules are designed such that motors operating at output levels higher than 750 watts of power will deplete the available electrical energy allowed for the class before completing the race distance. Thus, a competitive effort requires managing electrical power to levels below 750 watts. The energy and distance limits will showcase to the public what amazing things can be done with a commercially manufactured bike providing a legal amount of assist.Ã¢â‚¬Â
Well--the verbiage can be tweaked, but thatÃ¢â‚¬â„¢s my idea. Forget about explicit power limits and forget about the 20 mph limit too, and it appears that everyone but Mitch, by mistake, has already done so.
No oneÃ¢â‚¬â„¢s interested in racing at 20 mph. Furthermore, defining and measuring electrical output in any reasonable manner is impossible. So much so that the feds didnÃ¢â‚¬â„¢t even try to specify how power is measured (and how it's measured makes a HUGE difference). Simply let the energy and distance constraints do the job for the event.
> Of course you can certainly use a less powerful motor, it could be an advantage!
A less powerful but. perhaps, lighter motor would only yield a significant advantage on hilly courses, due to the possibility of reduced weight and the difficulty of re-couping the additional potential energy "stored in the extra weight" in the faster and aerodynamic draggy, downhill segments. ItÃ¢â‚¬â„¢s actually a little complicated, but weight isn't a big performance factor at PIR. You may certainly keep the comment, but itÃ¢â‚¬â„¢s a false notion for PIR.
As you are probably aware, specifying the battery capacity limits is a thorny challenge. but the additional energy permitted by the rules for lead acid packs is unjustifiable. Take my class, for example:
Battery Chemistry Watt Hour Limits (calculated V X Amps)
Division 3 40 miles (20 laps)
Lithiums Nickels Lead Acids
960 1152 1440
Apples to apples specifications? I get 50% more energy, if I run SLAs? Whoaa! IÃ¢â‚¬â„¢ll take lead acid, thank you! This is a no-brainer and my preference for lead acid batteries is not even close; the extra weight of a lead acid pack wonÃ¢â‚¬â„¢t be a factor at PIR (or nearly anywhere) and the higher internal resistance, compared to the other chemistries, wonÃ¢â‚¬â„¢t be a factor either, given the low power limits implied by the energy vs. distance requirements of each class. ThereÃ¢â‚¬â„¢s no standardized way to measure battery capacity and this is also very much a problem. I donÃ¢â‚¬â„¢t know how to solve it fairly, without a bunch of complications or the use of very specific Ã¢â‚¬Å“formulaÃ¢â‚¬Â class type rules, but different allotments for different chemistries doesn't solve it and it's not justifiable, given the "under-powered" nature of the classes. By underpowered, I mean, if my Division 3 class were something around 20 miles, then the LiFePO4s I ran would have an advantage over SLAs, simply because they have less internal resistance than SLAs and I can pull much more peak energy out of them than I can pull out of SLAs--but not for 40 miles! At 40 miles, if measuring capacity "apples to apples," the only advantage LiFePO4s offer is reduced weight over SLAs, which, again, is not a significant advantage on the flat PIR course or any race track I've ever raced (including the hilly Sears Point in CA--it's just not hilly enough for the weight difference to be a large factor for an ePower Challenge at the low electrical power assist levels that are in the ballpark of the federal manufacturing standards power levels). Or, taking my argument to an extreme, LiFePO4 batteries offer a huge benefit over SLAs for Killacycle drag racing, but not the ePower challenge at PIR.
Much fun and, once again, thanks,