If the dome is inflatable, that means she will be riding in denser air than the surrounding 6000' altitude. Not smart.

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res, non verba

I think it's got inner and outer layers, and that is what is pressurized.

But even if the interior was pressurized, it would be only a tiny fraction of an atmosphere. 0.1 psi would be a lot. 14.4lb/sq ft, and about 1,000,000 lb on the whole dome.

I have heard chatter that the pressurization equates to around couple hundred feet. Not an issue. One has to consider the OTC track with the dome one of the fast in the world.

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The Aguascalientes track also sits under an inflated dome. I did a calculation on its effect on air density. It's there, but it's tiny. You don't actually need much pressure to hold up an inflatable dome.

I don't know about the concrete surface at the Springs but I've got some data files for a rider using the same equipment at an outdoor concrete velodrome and an indoor wooden track. I don't remember exactly what the Crr difference for this rider and equipment on those two particular tracks was and I'm loathe to dig it up and re-calculate but my recollection is that while it wasn't tiny, it was small.

I've been in a couple domes like this, it uses pressurized ribs to maintain structure (like a raft). The inside is not pressurized at all (other than the minor positive pressure you get from the HVAC units). I think it gives a significant advantage from a climate control standpoint as well. She can decide how warm or cold she wants it, with the low humidity and high altitude here she could have it relatively cold and still face less air resistance than at most other locations.

No idea on how the concrete vs wood will affect the run, though given it's the olympic training center I can't imagine there would be many better facilities out there for an attempt. I'm close enough I might actually go down for the weekend and watch.

Good luck to her.

I don't remember exactly what the Crr difference for this rider and equipment on those two particular tracks was and I'm loathe to dig it up and re-calculate but my recollection is that while it wasn't tiny, it was small.

I wonder what the reason is for wood being better. If there even is an inherent reason.

Seems like it would be easy enough to make the concrete very smooth if it isn't cracked. You could even paint it with something. But maybe it's hard to prevent little undulations and such. Seems like it would be difficult with wood also, but I don't know. Concrete is harder, but maybe that isn't a good thing, if the wood is mostly elastic?

For outdoor tracks the choice is concrete because of durability, not because of the lowest possible Crr. Stevens is making the attempt now before the dome gets removed.

I definitely understand why concrete would be chosen for outdoors, it's why wood is faster for indoors that has me puzzled. I've never ridden on either.

Wonder what distance she will do? Beating the current record shouldn't be difficult for her. I think the women's record may get to 50km before long, but not this time.

It's hard to make a concrete track in smaller distances (like, 250 m) because the turns need to be banked steeply. That's why outdoor tracks tend to be longer: they're made of concrete for durability, but you can't easily bank the turns as much so they need to be longer.

I find the women's hour record even more exciting than watching the men's because there seems to be more room for an outsized ride that could smash the existing record.

The current record isn't very strong so she will "smash" it. It wouldn't surprise me if she broke the 50k mark

At women's WR speeds, COS would be worth approx 1.5km +/- 0.4km extra distance over a good sea level track.

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Jeanni Longo did 48.16km in superman position in Mexico City, I don't think we will see 50km any time soon. The current record is quite good, especially for a sea level attempt!

Humid air is less dense than dry air.

Thanks for the info. I would have guessed a little less benefit, but it depends on how her power scales with altitude.

I'm curious about how different tracks vary in speed due to material, smoothness, banking, etc. The fastest tracks are usually wood, and of course these are indoors. I don't know if concrete is inherently slower, or if it's just that wood is cheaper to use if it's going to be enclosed anyway. Any ideas? Do you have experience with both?

46.88 + 1.5 = 48.4

Humid air is less dense than dry air.

Yep, get those humidifiers and heaters cranked up.

Jeanni Longo did 48.16km in superman position in Mexico City, I don't think we will see 50km any time soon. The current record is quite good, especially for a sea level attempt!

The difference between men's and women's records for the Merckx rules was 46.065 vs 49.700. Only 3.6 km.

I'd guess the reason why there was a relatively small difference between the women's Merckx and superbike speeds (compared to the men) was due to a lack of funding and interest among the women who would have been capable of putting it over 50km. I definitely expect to see > 50km before long if the women get serious.

Stevens is the first attempt we've seen lately by a top pro, but I have no idea what her preparation has been for this. The plan might be to just beat the record. Get some publicity for herself, the team, and the track before more serious attempts are made.

Interesting, for whatever reason I thought the dome would stay in place year round but apparently that was never the plan. I guess the burden to cool it over the summer is more than the labor to add/remove it each season.

rruff wrote:

Thanks for the info. I would have guessed a little less benefit, but it depends on how her power scales with altitude.

Hence the variability quoted.

http://alex-cycle.blogspot.com.au/...record-part-iii.html


e.g. Molly Shaffer Van Houweling in an hour ride at Carson rode 44.173km and in 3 subsequent hour rides at Aguascalientes averaged 45.999km (45.637km, 46.088km, 46.273km) a difference of 1.826km to the average distance at sea level (1.464km, 1.915km, 2.100km respectively).

Considering that at each attempt Molly likely improved her technical execution as well as some aero refinements and possibly form as well, then seeing the gap at the higher end of my estimated benefit range does not surprise me.




Most concrete tracks are not super smooth, and certainly don't roll as nicely as good wood tracks (the exception in my experience are tracks that are made of large sheets of timber rather than the thin timber strips used in most modern tracks). I'm not sure why this is the case but quality timber surface is definitely faster to roll on. Perhaps there is some inherent "give" in timber that helps.

As to other factors to consider, it's often easier to maintain a good line on a larger track such as COS 333.33m and that can be an advantage. The slight downside is the centre of mass travels further per track km on larger tracks than on smaller ones.

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She'll need ~ 1250W/m^2 for an hour.

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She'll need ~ 1250W/m^2 for an hour.

To beat the record, I guess (not 50km). Seems too easy, .17m^2 yields 213W.

Doing the maths is the easy part of an official hour record attempt.

Actually doing it is the tricky part. That just requires her to ride at less than 25.6 seconds per lap on average for an hour on the nominated day and time. In this game, all that matters is being able to sustain the target lap times. That and meeting all the requirements of an official attempt and the logistics involved.

IOW all one need do is get to a track a see how long you can sustain WR lap times. Do it for about an hour an you're in with a shot, provided you have the time and resources to make it happen. Nowadays attempts cost between $50-100k to do.

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Sorry I wasn't more clear, what I meant was she would be able to more carefully control both temperature and humidity to be more favorable than someone like Wiggins run at sea level where he had it quite a bit hotter/humid than might have been ideal for pacing. She could choose to keep the dome cooler and/or less humid and still face less air resistance than Wiggins did. If she is really pushing for a remarkable run she can jack both heat and humidity up significantly and really try to shatter the current record.