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Old 08-28-10, 10:18 AM   #1
Dbl E GT
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Bike power transfer and efficiency --- Anything left to do?

Just a thought on this nice Saturday afternoon.....

With how efficient bicycles are these days, is there anything left for manufacturers to do to further the power transfer into the cranks so that more rear wheel torque is realized? In other words, how much further can Shimano go in developing components, such as Dura-Ace, to more efficiently transfer human energy into usable power at the rear wheel?
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Old 08-28-10, 10:56 AM   #2
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you're looking more at frame design than drivetrain at this point. it's not like the chain is flexy, and the chain would be the one malleable link in your drivetrain. there is more efficiency to be gained in keeping parts from moving needlessly than there is to be found in drivetrain.
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Old 08-28-10, 11:04 AM   #3
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Here on the west coast. I just woke up.

But Shimanos Dura-Ace Doesn't really "increase" anything, It's just as light and smooth as it gets.
I believe there are still the possibility of advances. With companys making things like the NuVinci Bike Hub (unlimited gears) and the Carbon drive systems now.(that don't stretch) They might not be super cool to some.


This Ciclotte Concept bike is actually going into production. How about that. $10,000 price tag. Though it isn't really for riding. I believe its a stationary exorcise bike.
You can read more about it HERE on Engadget
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Old 08-28-10, 07:43 PM   #4
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I think drive train efficiency improvements can be boiled down to three goals:

(1) Lower weight. This isn't "drive train efficiency" per se, it's just reducing the amount of power you need to put into the wheel, just like removing weight anywhere else.

(2) Quicker, more precise shifting. Indexed shifting was a huge step, since you no longer needed to fumble to position the derailleur correctly. Assuming proper adjustment, of course. Electronic shifting should further improve speed and precision.

(3) More gears. This allows the "engine" to run closer to the peak of the power curve. So you get 11-speed from Shimano and Campy's high end, and the CVT of the NuVinci.

None of this really involves eliminating friction or transferring power more efficiently from the cranks to the wheel. Not much to gain there, I think. Efficiency is more about improving the human-machine interface.
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Old 08-28-10, 09:14 PM   #5
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and with di2 taking any guesswork out of the game, all 3 of the "high end" setups being close enough to perfect, and material weight being made a moot point by sanctioning rules demanding a minimum weight for full bikes, there isn't much more to be done in drivetrain
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Old 08-28-10, 09:26 PM   #6
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Ask Andy Schleck if there are any further improvements that could be made to the drivetrain, or if we've reached drivetrain nirvana.
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Old 08-28-10, 09:43 PM   #7
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Ask Andy Schleck if there are any further improvements that could be made to the drivetrain, or if we've reached drivetrain nirvana.
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Old 08-29-10, 12:58 PM   #8
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As far as drivetrain efficiency goes, there haven't been noticeable improvements for 120 years. When you're already at 95% efficiency, even going to the theoretical impossible maximum of 100% wouldn't be noticeable except in time trials.
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Old 08-29-10, 01:08 PM   #9
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Improving aerodynamics is where a lot of gains could be made but you're not going to see much in terms of improvement coming from the racing world. The rules put strict limitations on the type of bikes that can be used.

Recumbents and bikes with fairings can be much more efficient than traditional diamond frame bikes.
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Old 08-30-10, 11:58 AM   #10
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It's all about the motor.
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Old 08-30-10, 12:55 PM   #11
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If there is an answer currently available wouldn't it be this?
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Old 08-30-10, 01:03 PM   #12
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If there is an answer currently available wouldn't it be this?
Yeah, but where is the space for a rack and MagicShine light? At least you won't need to worry about fenders
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Old 08-30-10, 01:39 PM   #13
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The inefficiency of a "less than perfect" chainline is a small problem that could potentially be improved. I know that this is maybe only 1-3% of total efficiency lost, but perhaps something could be done about it once the technology of frames and other parts plateau.
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Old 08-30-10, 01:53 PM   #14
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IGHs made of superlight Unobtanium, bathed in zero-friction nanooil, controlled by neurotrasnmitters?
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Old 08-30-10, 02:22 PM   #15
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I like the idea of a variable ratio gear system (that loses nothing to friction of course) where you set your desired cadence.
If you slow down, as on a hill, the gear inches would decrease. If you start to spin faster then the ratio would increase! You should be able to adjust the cadence automatically with a heart and respiration monitor to get max efficiency at all times.

What?

Oh, back to work.
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Old 08-30-10, 05:31 PM   #16
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to more efficiently transfer human energy into usable power at the rear wheel?
The largest inefficiency is due to braking... all that energy that you've put into the bike is now being thrown away as heat. Some form of motor + battery charging system (similar to electric cars) would improve the efficiency of the system.
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Old 08-30-10, 07:07 PM   #17
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I don't see much room for improvement on the drivetrain that we have today with a chain. I can see a skinnier belt, or something. That can accommodate chain rings that are much closer together giving the bike more gears and a straighter chain line. A belt that doesn't sag and is rigid so energy isn't wasted on a bouncing chain line but can also be pulled around a crank.

Maybe some time in the future there will be a wheel that can change it's size depending on speeds. A smaller front wheel to help with acceleration but slowly grows (?) to go along with speed to improve high speeds.

I'm just vomiting ideas, but hey, wherever the future takes us right?
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Old 08-30-10, 07:32 PM   #18
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The largest inefficiency is due to braking... all that energy that you've put into the bike is now being thrown away as heat. Some form of motor + battery charging system (similar to electric cars) would improve the efficiency of the system.
any efficiency gains here would likely be offset by the weight of the system. i think re-gen braking is a good idea for e-bikes, but not for bikes that are solely human powered.
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Old 08-30-10, 08:31 PM   #19
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Hey, loving all the brain bending here. Have some really smart forum members here !
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