Training & Nutrition - Help determining race pace from training

I'm thinking about siging up for an "ultra-long" time-trial called the Iowa 24hour challenge.

I know how fast I can ride for an hour or two. But how can I figure out how "hard" to go out at on a 24hour event?

Should I just go at a known 3 hour pace and see how long I last?
Should I just stay at 80-85 of MHR? Start to finish?

Any ideas or comments appreciated.....

Thanks....

Ride your normal pace. Keep hydrated and nourished; the water and food is what will keep your muscles going.

Take the word "race" out of your mind. Concentrate more on finishing.

Take the word "race" out of your mind. Concentrate more on finishing.

Good advice. I know that dh is on a compleatly diff level then a long road race but this season I took a friends advice. He told me not to worry about "Racing", concentrate on finishing. Well needless to say I took that advice and found that I road much smoother, used less energy and ended up being faster down the hill. I would think it would work the same for you. Try to ride a smooth comfortable pace and concentrate on finishing. You just might finish faster then you think.
Slainte:beer:

Take the word "race" out of your mind. Concentrate more on finishing.

i think that's some pretty good advice...

i've actually never done a 24h race, but i've done a bunch of long adventure races and a 2-day race as well as 8-stage AlpCrossing (just 2 weeks ago although it wasn't a race)... as someone also mentioned, keeping your body going is one of the biggest challenges: keeping hydrating, getting enough food that your body can digest w/o getting sick, getting the right nutrients so you don't get muscle cramps (i would REALLY recommend adding Magnesium and Calcium supplements to your water for such an event - as well as an energy drink but you probably alrerady do that if you're thinking of a 24h race)... and just keeping yourself going mentally...

on a more technical note: for the most part, for any length of ride you have the same total amount of "reserve" energy until it can be regenerated. This is usually defined as time above your lactate threshold (or anaerobic threshold or LT or AT) which for typical cyclists is about 15-20 minutes. for well-trained cyclists it can be 30 minutes or more. This means that in a 3-hour race, you can go pretty hard and maybe spend 5-10 minutes an hour on short-sprints and still have reserves left... for 24-hour race you most likely cannot sustain this b/c you will deplete the reserves and while continuously riding your body will not be able to regenerate.

although i didn't do a true pace comparision (we did an average of 2,000m vertical per day so it's almost impossible to compare)... on my "easy" days i had about 5 minutes above LT and on my "hard" days about 20-25 minutes and was then sore and weaker the following day. (i wasn't able to recover as much and regenerate the reserves)

So... i would say for a good estimate, do a 1-3 hour ride at near-max BUT NOT SPRINTING or MAX... where your heart rate is just below your LT threshold pulse (i.e. 5-15 beats below -- e.g. my LT is 165, so between 150 and 160). this will give you your BEST CASE pace, assuming you have no nutrution, hydration, cramping, mental difficulties, etc. that might slow you down. also have to take a little time off for more stops like for refilling water bottles, picking up more food, maybe changing batteries -- this depends much on how much and what kind of support you will have.

i don't want to write too much here... but basically the LT is the level above which the body cannot sustain for extended periods of time b/c the body is unable to get rid of by-products AND your primary energy system changes from "sustainable" aerobic activity to [more] short-term aerobic energy of which you only have limited supply. SO for a 24h race, one of the most important things is that you DO NOT exceed this level (for a minute is OK)...

I'm pretty sure 24 hours will go by no matter what -- so I'm pretty sure I'll finish the race... (a true RC thought)

But I guess what you meant about trying to "finish" the race is to keep riding for 24hours.... and I kind of think I CAN do that...
Actually I was going to shoot for 22 out of 24, less than 30 minutes for the first 12 hours...

I guess I'm going to go out just like it was Century ride. Most of the time I finish those OK. I don't want to back-off needlessly if it isn't going to really do me any good.......I doubt I'm going above LT much on those rides anyway....

Thanks.