Engineering of fixed gear

Since 2001, over 90,000 cyclist's have joined Cycling Forums to discuss topics from general cycling to equipment, training, racing and travel or vacation destinations (especially in europe during the tour de france). We also feature an great deals in our online store, 100's of articles, classifieds and product reviews.

So, to all the physics majors/engineers out there, why is it so much easier to spin a hill on my pig-like 46/16 fixie as opposed to my pretty little 3rensho racer with 14 different gears to choose from?
I mean, really, the 3rensho is lighter, much thinner tyres, tighter geometry, and with the fairly low gearing it should be much easier to bop up the hills, but it feels horribly sluggish. Would the freewheel/derailleur account for this, or is it all in my tiny brain?

All those nice shiny bits give you driveline drag.

Too add, when forced to stay in a tough gear one is more likely to have to charge just to keep going. On your other bike you might feel like you are working hard, but you make the decision, not the bike.

I wondered the same thing about my fixed gear and multi-geared bikes. I don't have the answers, but I'm guessing that part of it is that when the fixed gear bike gets rolling, even uphill, it does some of the work for you...the moving rear wheel helps keep the pedals going. (?)

I wondered the same thing about my fixed gear and multi-geared bikes. I don't have the answers, but I'm guessing that part of it is that when the fixed gear bike gets rolling, even uphill, it does some of the work for you...the moving rear wheel helps keep the pedals going. (?)
I think that could be some of it, you have a smoother, more continuous stroke that is easier to maintain. You also don't have anything else in the driveline to leach energy. On my fixed, it also seems like the chain wraps on more of the cog, possibly able to transfer torque more effeciently. Also, I think there has got to be some work lost in spinning a crooked chain.

All those nice shiny bits give you driveline drag.
actually, the geared drivetrain only takes up about 10 more watts to spin than a singlespeed. that's not enough to make you noticably faster.

actually, the geared drivetrain only takes up about 10 more watts to spin than a singlespeed. that's not enough to make you noticably faster.
It depends on what gear you're in. If the gears are lined up, then you're only dealing with added drag from the derailleur pulleys, which is pretty small. But when you use a gear that has a lot of cross, the plates on the chain are rubbing against the sides of the gears. This causes a big drop in the efficiency of the drivetrain.

[QUOTE=franklin pierce]So, to all the physics majors/engineers out there, why is it so much easier to spin a hill on my pig-like 46/16 fixie as opposed to my pretty little 3rensho racer with 14 different gears to choose from?



You need to work on your pedal stroke.
The fixies like a semi-automatic; It does part of the pedaling for you.
You're probably just pushing down.
But with an improved pedal stroke and proper gear change you should be killin' it on the hills with your road bike.
www.kingzoftheroad.com