4 ms·

A little background on this and a thought: Friction Facts started out as a guy (with an engineering degree) that developed his own test equipment to measure dr

by parsimo2010 7y ago

A little background on this and a thought: Friction Facts started out as a guy (with an engineering degree) that developed his own test equipment to measure drivetrain losses under load. He eventually published his own wax formulation so that a DIYer could replicate his best effort at reducing chain friction. It produced a chain that had about 4 watts of loss, which is pretty good. That's over 98% efficient for a person putting out 250 watts. 250 watts is high for someone that's never ridden a bike, doable for someone that commutes by bike every day, and a pro wouldn't even break a sweat. So going to 99% improvement, or "reducing friction by 49%" sounds like a lot, but you're only gaining back 2 watts out of 250. Also, Friction Facts felt really cool when is was just a backyard engineer publishing his results, but then he got bought and took all his results/website offline. Luckily the internet archive and many forum posts have the major results, but it felt kind of like he was selling out to the man. I understand that he has bills to pay so I'm not mad at him. I also understand that a regularly lubed bike chain has higher than 4 watts of loss and most people aren't willing to melt wax on their stove to wax their own chains (I do though). The CeramicSpeed concept couldn't shift in 2018 and they haven't demoed a shifting version as of August 2019. The pie plate at the back is only for looks, and claiming 13-speeds is totally worthless at this point. Heck, I could CNC a 30-speed cog for the back, since it would fit inside the diameter of the wheel. I predict that when a shifting system is functional, it will increase the complexity and add to the friction of the drivetrain, bringing to about the same level of friction as top end chain based systems from Shimano, SRAM, and Campagnolo. This is a promising idea, but ultimately it's worth more as a way to avoid patent infringement than it is to make a faster bike. Another smaller player, Rotor, makes a 13-speed system that shifts hydraulically. Rotor's marketing claims that hydraulics shift better, but everyone knows that it's just a way to keep from stepping on the established players' toes.

LeifCarrotson 7y ago
In round numbers, the drivetrain causes about 4 watts of loss. Tire rolling resistance costs about 40 watts (on regular roads with road bike tires; less in a velodrome and more with knobby, thick mountain bike tires). The bike itself costs 8 ~60 watts or so in air resistance, less for aero, deep-dish tri bikes and more for round-tube wide-tire gravel bikes. But more importantly, air resistance increases with the square of velocity, no matter your starting drag coefficient. The remaining 150 watts or so are caused by rider air resistance. And of course, all 250 watts are produced by the rider and dependent on their fitness level. Clearly, the best way to go faster is to put more energy in. Next, improve your posture to produce less drag. However, it's easier to spend money than to sweat and suffer, so people instead turn to aero bikes, tires, and the drivetrain.
- track_me_now 7y ago
  >> However, it's easier to spend money than to sweat and suffer not disagreeing with anything you're saying, however at the super-elite level everyone puts in the maximum amount of perfectly allocated effort into training and preparation. if we could eliminate 4 watts of drive train friction loss that would be material. For your average weekend warrior the points you make are definitely true, but hey, not the worst thing to blow your money on...

LeifCarrotson 7y ago

In round numbers, the drivetrain causes about 4 watts of loss. Tire rolling resistance costs about 40 watts (on regular roads with road bike tires; less in a velodrome and more with knobby, thick mountain bike tires). The bike itself costs 8 ~60 watts or so in air resistance, less for aero, deep-dish tri bikes and more for round-tube wide-tire gravel bikes. But more importantly, air resistance increases with the square of velocity, no matter your starting drag coefficient. The remaining 150 watts or so are caused by rider air resistance. And of course, all 250 watts are produced by the rider and dependent on their fitness level. Clearly, the best way to go faster is to put more energy in. Next, improve your posture to produce less drag. However, it's easier to spend money than to sweat and suffer, so people instead turn to aero bikes, tires, and the drivetrain.

track_me_now 7y ago
>> However, it's easier to spend money than to sweat and suffer not disagreeing with anything you're saying, however at the super-elite level everyone puts in the maximum amount of perfectly allocated effort into training and preparation. if we could eliminate 4 watts of drive train friction loss that would be material. For your average weekend warrior the points you make are definitely true, but hey, not the worst thing to blow your money on...