Quote:
Originally Posted by renault_megane_dci
Do we need this much gear reduction ?
The 250 crowd is switching from 1/3 final to close to 1/2 already without particular issues in 1st gear.
Unless you were to change to a diesel engine (and then the motorbike gearbox sounds like a good idea) I can not figure out the need for two gearbox in series on a motorbike engine ...
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As I recall (been a few years since I've ridden it) my ninja 250 with (as far as I know) stock gearing was spinning well over 10mph/1000rpm, to the point of being somewhere around 8-8.5k at 70mph. Even without any sort of fairing I would have needed another gear or two to get me to the point of cruising at close to full throttle. That could have been done just by final drive gearing; I recall starting off from 2nd a few times, no problem on the flat, but add a hundred pounds of full fairing streamlining and a steep hill, and getting going without stalling might take some work. And once it's been streamlined I'd think the engine would need to be spinning half as fast (or slower) as stock in top gear to cruise at close to full throttle. If you just do that with final drive, it would be similar to starting in 3rd or 4th on a stock bike!
Whenever I finally get a round toit (all the ones I've found so far are square, I may need to cut some corners
) and build a streamlined bike (or car for that matter) I'd like to have it geared where on the highway top gear at full throttle still needs a tail wind to hold a constant speed. Then if there is a tail wind I'm at maximum efficiency, or if no wind or a head wind I can pulse and "glide" between the top few gears, or just downshift as needed to hold my speed. This will take a lot of gears! (Hmm, I wonder if I can shoehorn a big rigs 18 speed under the hood of my vibe!
)