Well riding at constant effort is something else. I think the jury's out on constant effort in time trials vs hammering up hills.

I mean if you ride 10 mins at 230W, that's one thing. If you had a really steep up and a long down, then that might be 1 min at 300W and 9 min at 120W.. which would be faster? Hmm.

But you can't get more than the energy you gained out. Simple conservation of energy.

I could tailor a route to make it doable, but where's the fun in that. The GPS shows 24MPH on the flat roads and 17/19MPH on the undulating. If I knocked out the Chilterns with all the 12MPH climbs and moderated the pace elsewhere then it would be achievable.

molgrips, you seem to be suggesting that you'd be more efficient if you sprinted for a minute then cruised slowly to a standstill ad infinitum which wouldn't really work. It'll always be faster to work consistently at the lowest effort to attain the target rather than going above and below threshold (at least for this kind of 5ish hr effort).

FWIW, my mate did 497 (ish) miles in 24hrs last year 😉 (He did win the national 24hr TT, mind)

Clubber, I meant if you had a hill which was very steep on the upward bit and very long and gradual on the downward bit. I am weighing up the possible effects of this kind of hill in my mind…

The non-linearity of fatigue in response to exercise actually means that it's definitely easier to keep a constant pace. After all.. but hmm.. wait.. on the way DOWN, the faster you go the more energy you lose to air resistance.. time to dust of integral calculus.. 🙂

But you can't get more than the energy you gained out. Simple conservation of energy.

If you think this needs pointing out, then you've misunderstood what I'm getting at, since it should be obvious that I'm not that stupid!

thanks 29er Keith – I plan on splitting the double over two days with a nice sleep in between 🙂

You've got it – going fast (DH) is very inefficient since air drag increases exponentially.

Working hard up a steep hill is also inefficient as you move away from aerobic effort not to mention that it only works so long as you're well fuelled and relatively fresh.

Yes.. even a short anaerobic effort seems to take a lot out of you.

So the consensus – constant power, but slack off a bit on descents and take a few cheeky rests on the steeper bits.

I could tailor a route to make it doable

I don't really see the point in doing that oldgit, and I don't think you do either. I don't see the 'must get to 20mph' as a target to beat no matter how.

I always though faster climbing (to keep the average speed up) would be the key to better times (my best 100 round here undulating with a few short sharp climbs is 5:40) You don't think so Clubber?

could tailor a route to make it doable, but where's the fun in that.

Where's the harm though? Do it once on any course and you've broken the psychological factor of doing it. I'd have thought any 100 miler is going to have hills enough without searching them out, even undulating the height would rack up… can't see any possibility of it being easy!

I didn't say that fast climbing is bad! I just said that any climbing will reduce your average (the downhill will never 'pay back' what you lose). Climbing flat out will also reduce your average on a ride of the sort of length we're discussing. If you go hard up a climb then you'll need to recover from that effort at some point (since you can't sustain an effort over your aerobic capacity indefinitely without fading) – you want to keep within or as close to your aerobic limit as possible to be able to maintain speed over the course of the event – Tortoise and hare basically.

FWIW, I comfortably did 100 miles in 4:30 (a while back when I was fit…) but on the Bristol to Bath cycle path which is flat though it was reasonably windy. My average on hilly courses would have been significantly less.

I mean if you ride 10 mins at 230W, that's one thing. If you had a really steep up and a long down, then that might be 1 min at 300W and 9 min at 120W

If I understand this then you are saying that by doing 300W uphill you'll save enough time to drop your power by 50% to finish the remainder of the distance in the same time?

I may misunderstand but you are dreaming!

cynic-al – I was mulling it over.. and came to the same conclusion you did – see later post.

Although re nickc – if the climb is short enough ie less than say 20 secs, it may well be worth hammering up it since you may be using your ATP-PC cycle and not fatiguing yourself much.

One mountain mayhem I was on form and put in six or so laps all within a minute of each other, extremely consistent. However my average HR dropped from about 180 to 160. So I was getting more and more tired, but still putting in the same times. I think it was because I learned the course really well and I found myself putting in short sharp sprints up certain climbs at the right point allowing me to roll through much more efficiently.

Seems like my muscles had recovered enough ATP to sprint for short periods in the 3 or so hours between laps, but not to work flat out.

That's quite possible but 1 hr on, 3hrs off is not the same as a 5hr effort so different strategies will work.

FWIW, I comfortably did 100 miles in 4:30 (a while back when I was fit…) but on the Bristol to Bath cycle path which is flat though it was reasonably windy. My average on hilly courses would have been significantly less.

What? you did it 8 times?

No I know. But you see what I am getting at. During each lap I got the same times with different strategies, and less overall energy expenditure for the later ones. Now I admit traffic and familiarity with the technical bits may have had an effect…