Why no pedaling? That's just an e-moto then. But let's say the build is to be a demonstration of the effectiveness of electric bikes, which would actually be pretty cool to forward the cause. The best info I could find on the power requirements for the TDF, is from some scientific paper done to calculate Lance's power output for some famous climb, and they came up with 495 watts (6.97w/kg). I also found a chart of the watts/kg during the final climb of the mountain stages for some past winners,
http://www.sportsscientists.com/2009/07/tour-de-france-2009-power-estimates.html . These are essentially the peak continuous output, and the riders don't maintain that output for the entire 4+ hrs of each stage.
That tells me all you need is 500W continuous at the wheel with a similar total weight and you'd win hands down. Realistically that means about 600W continuous from the battery for over 4 hours, so call it a 2500wh pack. I've seen higher energy density claims at the cell level, but the Hobby City packs are about 140wh/kg, so you're looking at an 18kg battery pack. You'd build the batteries into the bike itself in a manner to have minimal impact on aerodynamics, though it is likely to end up susceptible to side winds.
To stay with these numbers you'd want to get a horse jockey to ride it, so you have a comparable total weight. They're accustomed to a tucked position and smaller than the TDF races. Plus, since he's not pedaling it wouldn't be too difficult get better aerodynamics than the TDF guys with a different leg position or partial fairing. It's all about power to weight, so for a more normal size rider, you'd need to increase the power. A 110lb woman as the rider is another option, though if you really wanted to make a promo statement, build the bike to US limits and run 750W continuous with a 3kwh pack.
For the motor, use something small and efficient that can handle the continuous output without issue. From what I can tell the hills may be steep for pedaling, but really not all that steep for ebikes, but you will definitely need variable gearing to keep the motor running in its prime efficiency range.
With an unlimited budget it would actually be pretty easy. The starting point would be deciding on what size rider, and what form the bike will take (fairings, normal upright bike shape, etc.). With no rules, then low, sleek, and a small rider could greatly reduce the battery pack needed.
I'm working toward a bike that would easily win the TDF carrying 110kg me (less by ride day), because it will need to go 260kms on a single charge, and in the middle of the route I need to cross a mountain range with the pass being a 1400m climb over 20km that includes some long stretches of 10-11% grade. Once the bike is built, then it's overall efficiency will dictate my speed, but I do plan on something faster than the TDF avg speed to make my day shorter. It's something I've been talking about for over a year, but now that my college age son is definitely not going to participate in the project, it's time to make some real movement on it. Too bad I don't have an unlimited budget.
John
ps- I was typing my post as Tiberius submitted his, so sorry about the duplication of some stuff. I'm too lazy to go edit it.
