I really don't notice any significant difference in effort between my totally flat 9mi commute with about a dozen stops on fixed (48x17) vs. multi-geared. On both I can complete in about the same (auto and elapsed) time on average, but can often top out at higher speed (30-35mph) on multi-gear to take advantage of tailwinds, etc which I can't on my current fixed ratio.

Putting hills into the mix would definitely change things though. Also if I didn't have stops and rode in a pack I'd want a higher gear on the fixed assuming flat roads.

Al

my experience w/ fixed gear vs. freewheel + gears on group rides w/ roadies:

there's really not too much difference between the 2, output/exertion wise. the main difference for me was on long downhills. i'd get dropped on these b/c i just couldn't spin like that for so long. to hold 30+ mph for a while gets tiring. but really, that was it. hills are taken at such speeds that the big gear really wasn't a problem. i started out doing the rides on a fixed gear bike, and thought that it would be so much easier on a geared bike. then when i got a geared bike, it was dissapointing to learn that it wasn't a whole lot easier. the hard bits are still just as hard. don't tell the roadies though. when i go on group rides w/ the fixed gear, they tell me i'm a beast.

Yeah and then you can mash up it and get new knees in about 10 years. Given the same combined weight of two riders, one in low cadence and one in a higher cadence, same speed. You're outputting the same amount of power to get up that hill.

Yeah I know power output is the same if the total work/time is the same.

The thing is lower cadence takes more force. It's like to going to the gym and lifting 300 lbs for 10 reps in 30 seconds vs 150 lbs for 20 reps in 30 seconds. Both feats power-out would be same, but which one is harder and provides greater resistance?

That was just an example. I'm not advocating training in any particular way. God knows low cadence won't help your endurance.

I understand the general dynamic of lowering your gear for a hill, but what I typically see is roadies doing 80-90 rpm on the flat then gearing waaaaay down when they hit even a slight hill and upping their rpms to 100+ while dropping their speed to 8-10mph. Maybe it is because they just go into 'hill mode' or something.

too much lance-emulation, methinks.

I don't see this. I do often see a drop in effort though, like folks are saving for the tops of the hills, but then they never pick it up again. I like to keep a constant effort, which results in less of a speed drop at the bottom the hill and a more sustained speed overall (assuming constant gradient)

Al

Or, if you don't know the hill, you'll keep your pace well below LT, lest you get stuck on a switchback or something and end up falling over.

That said, I try not to hit less than 10 mph on a hill on the road bike -- I do a lot of climbing (2+ mile ascents), but only rarely will I do climbs that average more than about 8.5%.

But this is about fixed gears, and the answers is that, for me, stopping on a downhill is what kills me. Here in SF, I've gone down some huge hills, and even with a brake I feel like I'm not always going to stop in time. Amount of extra energy: lots.

I live in flat land for commuting (plenty of nice hills if you get out of the city) and I am always in amazement at folks who ride fixed gears in SF and other hilly places. Not just the up, but the down - I just don't see how one can have a nice cruising gear and still have it low enough to tackle the hills.

Al