donrhummy

Any idea how the speed tends to translate? Is there any way to translate it? If so, which direction does it go? For example, can a 100 mile speed help predict an approx. 50 mile speed but not vice versa?

What have your speeds (while trying hard) been for these two rides?

SDRider

Huh?

I've ridden 50 miles and 100 miles. Not sure what it is you're asking though.

Psimet2001 

+1 - Speed is sooooooooooooo dependent upon eating, course, weather, etc. that you really can't predict your speed for one by using another route.

Example:
I usually ride a 16.5 mph century, but I have twice ridden 160 miles at 17.5mph or greater. Difference? The 160 course was West to East one way. Wind at your back for most of it. It's just too dependent upon the course.

damocles1

Depends on the group that shows up as well. On Saturday, 5 of us did 55 miles in 2:45. On Sunday, the century in Charleston got clipped off in 4:08 by the lead group.

botto 

E=mc²

VegaVixen

If you hit your so-called sweetspot on cadence, etc., you'll feel like you can go on forever. Your average speed at that sweetspot, will likely be more or less the same over 30-, 50-, or 100-miles, given the same terrain and wind conditions.

If you're talkin' about gettin' outside that sweetspot and tryin' to ride hard, you'll have a higher average speed over a shorter distance, given the energy expenditure and fatigue to your legs. Think about running. You can obviously do a faster pace for one-mile than for 10miles, if you're racing. If you're in your sweetspot for long-distance, though, you'll likely have essentially the same pace over your 20th mile as you did over your first.

rknj

Distance doesn't matter nearly as much as elevation changes.

SDRider

Correct.

SDRider

Agreed. I tend to average about the same pace on longer rides as I do on shorter ones. Wind and hills are usually the only things that change my output...other than fatigue of course.

joshalope

If a train leaves Pittsburgh PA at 8:15 am and heads west at 100 mph, and another leaves Needles NV at the same time, but heading east at 80 mph where and when do they meet? Show your work.

fuzzthebee

A general rule of thumb is that power output drops by ~5% as the duration is doubled. So if you could ride 50 km at an average of 250 w, then you could do ~100 km at ~238 w.

If you plug those numbers into a speed/power calculator, you get just over 37 km/h for the 50 km in 1:20, and 36.5 km/h for the 100 km in 2:43. No big difference. Those figures are, of course, highly variable.

slowandsteady

80% of your 1 hour average speed, assuming similar terrain.

DXchulo

That's tough. This question is all but impossible to answer.

I could ride 50 miles very hard without food and not feel too awful bad at the end. I could never do the same thing for 100 miles.

I think if you're doing 100 miles for the first time you should throw "very hard" out the window. You want to know you can actually go that far before you start pushing for speed. I do at least a century every month and next week will be the first one where I'm actually concentrating on speed. You have to build up your endurance first.

Even if you're trained pretty well you'll always be able to average a higher speed for 50 miles than for 100 miles, even if conditions are perfectly equal, which will never be the case. You can go anaerobic in a 50-miler and it won't catch up with you later as much as it would for the 100-miler.

corny

Probably around 10% diff between 50 and 100 miles same conditions, but as said this is never the case - so go test it for real

kensuf

Too many variables (hills, wind, road conditions, etc) to get a real estimate. But you should be able to get a rough idea under "like conditions" based on all the riding you do to prepare for a century.

50 miler? My best pace was about 23mph. 100? About 21.

oilman_15106

Agree, lots of steep climbs, as we have here in W. PA will just kill your average speed. No matter how great a climber you are.

Endox

Even in ideal conditions depends how regularly you do the larger distance I guess, if you don't have the endurance base then the 100 miles will probably be at a much slower pace than the 50 miles which you are used to, OTOH if you regularly do 100 mile rides then the pace shouldn't be too much slower.