Road Cycling - Ave Speed on Hills vs. the Flats

Coming from a mountain bike background, average speed doesn't mean much as the terrain varies so much from trail to trail. However, I hear a lot of talk of average speed on the road. My question is this:

Does average speed vary much over a route with hills vs. a route in the flats? In other words, are the slow climbs offset by the quick descents??

ThanX!
:D

Nope.

I moved from the scenic hills of the Ozarks to the flatlands of central Indiana and gained 3mph on my average speed for a 25-40 mile ride.

Except for Lance you go up the hills to slow to compensate with the down.

I think it varies quite a bit with me. I have a number of after work rides that average 30 miles. Some routes are much flatter and my ave. speed can be 2 mph faster than the hillier routes. Also, you have to take into account of how many times you stop(stop signs, traffic lights etc.) . It is always nice to have that one 'hard' route that makes you work.

The fast descents do not make up for the slow climbs because you are going slower for a lot longer than you are going faster.

Therefore your average speed will always decrease with hills involved.
:)

Whats a hill?

I have noticed that really pouring it on on the flats and taking decents at (for me anyway) insanely risky speeds doesn't seem to have as much impact on my average speed as I would have expected.

I use my average speed for several of my regular routes as a means of guaging my improvement with training, particularly on the hillier routes. I use bettering my best average speed as a training target.

I figure a 2 or 3 mph increase in my average speed over the course of a season on a moderately hilly 30 or 40 mile route indicates a pretty OK improvement in my fitness.

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Whats a hill?

HAHAHAHA are you from florida?

Check out my latest post called "Quiz Time" in General Discussion for a fun little problem on average speed!:)

Mike

Never mind, I found some hills. Yesterdays ride, 64 miles and 7,000 feet of climbing, the longest one 4 miles, climbing up out of the valley by stockten mn. several others of a mile plus. one at 12% grade a little over a mile. Ouch!

13.7 mph ave for the day

No, slow climbs are not offset by quick descents (assuming that you put the same amount of power into each). The climb takes much longer to do, so the impact on your time is greater (hence slower average speed).

For example, a 5 km climb that takes me about 20 minutes to do (15kmh), will take me 5:37 to descend (at 53.4kmh--using same wattage output). Total for 10km = 25:37, average speed is about 23.5 kmh. With the same wattage on the flats, I should be able to average 33 kmh, meaning that my time for 10km total would be about 18:11. (I say "me" here so that I can use my weight, etc. for the calculations.)

The more important conclusion from such examples is that average speed is almost useless as a measure of fitness or the quality of a workout. I dutifully record my average speed in my training log, and I have watched my average speed climb over the course of a season. Sure, I am getting fitter. But, on the daily or weekly level, average speed says nothing about what you did on the workout (intervals, hills, endurance, etc.).

The best proof of this is that a really windy day (or a really hilly day) will kill your average speed, but it will have been a tough workout, despite the "downwind" sections.

Cheers,
Jamie

I live in Atlanta (hills) and do most of my riding in town. I've ridden about 10 times on a rails to trails path this year (flats). I've logged all the computer data for every ride all year. The avg. MPH on the flats is within 1 MPH of my avg. for hills. Based on my data, I'd say one's avg. MPH is one's avg. MPH whever they are.

Bikes-n-Drums,

I, too, have found my average speeds to be pretty consistent, regardless of my route.

Nevertheless, in theory, hills will slow your average speed, provided that you are putting out about the same wattage in all portions of the ride. This is what physics tells us, in theory.

By necessity, my physical calculations simplify real world riding, since they assume no headwind, and they do not account for acceleration/deceleration. And, they assume that you put out the same power throughout (otherwise the comparison would become meaningless).

I suspect that the similarity in average speeds reflects the variations of real world riding. Furthermore, real world riding is never headwind/tailwind free. Add traffic lights, pee breaks, whatever to the mix, and all that acceleration/deceleration plays a role that the equations can't model. Since I like the challenge of conquering a mountain, I usually put out higher power/watts on climbs than on the flats (my bike computer tells me my wattage output). This makes my average on climbs higher than what my average wattage would otherwise reflect.

The physical equations give us a model against which we can compare our real world observations. The unfortunate conclusion is that average speed as reported by the bike computer tells us very little about the quality of an individual ride. The consistencies in our average speeds confirm that we don't live in a physics lab--i.e. that we did *not* put out the same power throughout the ride, nor did so in headwind free environment, etc.

But, our observations don't tell us that the physics is wrong. Physics can be a nasty beast when you try to argue with it. It wins every time.

Cheers,
Jamie

P.S. I am happy to send you the equations or an excel spreadsheet which models them. Since I am not a physicist, I am also happy to admit any flaws in my equations, which I have cobbled together from a range of sources.

Originally posted by jeffathompson
Whats a hill?

Whats a flat (tyre excluded) ?

I believe a quick "rule of thumb" makes it to be appro 7% loss of average speed riding hills, as compared to flater terrain.