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How much faster on a flat course vs hilly?

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Mrdavidalex

Apr 5, 12 14:02

Post #1 of 10 (959 views)
 How much faster on a flat course vs hilly? Quote | Reply
I was wondering what my ave. speed difference would be if I did 1500' 50 mile bike versus 0' 50 mile bike ride. (assuming I put out the same wattage or HR).

matto

Apr 5, 12 14:12

Post #2 of 10 (939 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
Can't even begin to estimate that without knowing your weight, right?

Mrdavidalex

Apr 5, 12 14:15

Post #3 of 10 (929 views)
 Re: How much faster on a flat course vs hilly? [matto] [In reply to] Quote | Reply
185lbs

morey000

Apr 5, 12 14:23

Post #4 of 10 (916 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
hard to calculate unless you've got long sections of steady pitches. If you climbed 1500' evenly over 25mi and then returned- it would be different than having a lot of steeper ups and downs that accumulated to 1500'.

The steeper the hills, the slower the average speed. Not so much because you go slower up them... but because you come down fast and lose a lot of power due to air drag.

Jeff D

Apr 5, 12 14:39

Post #5 of 10 (896 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
Too many variables...go ride it and find out.

For a rough estimate - try the calculator at analytic cycling.
Assuming your hypothetical course contains 25mi of climbing at 1%, and 25mi at -1%, then using the default values (250w,CdA=.25, sea level, 75kg, Crr=.004) gives a time difference of around 96 seconds versus a flat course. (119.4min on the flat course vs 121.1min on the hilly one).

summitt

Apr 5, 12 15:11

Post #6 of 10 (858 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
I'll take a stab. I'm the same weight and do a lot of 50 mile rides from my home, which sits about a 1,000 feet above where most rides take me. 5 to 10 miles of uphill to home at times going 9 mph and I'm in the 39/25 - grades around 3-8%. Most training rides, riding fairly steady are in the 17.5-18.5 mph type of average. 50 miles of flat,even with wind like at Galveston this week I was over 20 mph+ for the ride, which resulted in a good run. I've never averaged 20mph on a ride from home. Best rides with hard effort and periods of longer flat stretches and I can maybe get to 19mph average. So depending on the terrain, wind,etc, I would say for the same type of effort your are going to be 1 to 1.5mph slower with 1500'+ of climbing. A few rolling hills to get you to 1500 feet would probably be a 1/2 mph slower, steep pitches and longer type climbs I would guess 1-1.5mph. I find at my weight I can maintain good speed on the rollers but short 300 foot steep climbs and weight becomes more an issue.

(This post was edited by summitt on Apr 5, 12 15:16)

phil combs

Apr 5, 12 15:35

Post #7 of 10 (817 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
I just pm'd you a Garmin file. On that ride I did a 50 mile ride with 3300 feet of elevation in 2:26. In the file you can see my average speed on the flat sections (24-25 mph) and the overall average for the ride (20.2 mph). My "guess" is that the 3300 feet of elevation added more than 20 minutes to the ride probably at least 25.

Three additional things. First, analytic cycling will answer the question. Second, it depends on how hard you are riding. The harder you are riding the less impact 1500 feet of elevation will have on the overall time (example, bigger impact at 200 watts than 300 watts). Third, one thing it's easy to overlook is that if you ride 50 miles on the flat you are in the same position the whole time--my neck would be killing me! But if you are climbing out of the saddle you are mixing it up and at least for me, it's a lot easier to have a ride where i am in a lot of different positions as opposed to just one position for 2 hours.

OneGoodLeg

Apr 5, 12 15:37

Post #8 of 10 (813 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
Yeah, that's so variable that any wild-ass guess is about as good as any other. Here's a scenario from one HIM I did where I didn't even avg 20mph... several big hills, but the 2 descents in particular where we got back most of the elevation were:

1) narrow and twisty so you sat up for a lot of it and had to brake in several spots, mostly didn't go much faster than 25mph or so which felt like a rip-off after banking all that gravity and then not being able to cash it in at anywhere near equal value, and

2) along an obvious old survey section line so it was very gradual and straight, and due west into a strong wind coming in from the coast so you had to work to pedal 30-35mph down instead of coasting at 40-45.

For comparison, I had a faster avg for both the IM splits I've done.

Mrdavidalex

Apr 6, 12 5:15

Post #9 of 10 (698 views)
 Re: How much faster on a flat course vs hilly? [OneGoodLeg] [In reply to] Quote | Reply
The only reason I ask because on Wednesday I did a 52 mile ride with 1500'(garmin watch). I was averaged zone 3 HR for the ride and ave speed of 18.7mph. I did IMFL last year and I ave 20.3 mph. The 52 mile ride seemed harder than the IM bike. There were a lot of rollers, 3 steep climbs, and long steady climbs. Maybe it was due to the fact that it was only my 2nd long bike ride this year.

summitt

Apr 6, 12 7:59

Post #10 of 10 (616 views)
 Re: How much faster on a flat course vs hilly? [Mrdavidalex] [In reply to] Quote | Reply
"There were a lot of rollers, 3 steep climbs, and long steady climbs"

Couldn't have been too many rollers or too long a steady climb if you only got 1500' in 52 miles. That's really not a lot of climbing over that distance. Your average speed is just about what I guessed at 1 -1.5 mph difference for same effort.