Depends on how fast you ride and yaw angle. But that might not be too far off at maybe 25mph. Less at slower speeds, but if your slower, you're making less watts, so total time savings would be even higher.

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TrainingBible Coaching
http://www.trainingbible.com

I can tell you that going from spokes and gatorskins to disk cover and 60mm front, and Corsa Evo and lightweight butyl (Mich Race) tubes gave me 25-30w. Unscientific but similar courses and mildly windy conditions on race day (56mi in 2:25:xx on 257w vs 56mi in 2:24:xx @ 232w). 15-20w is realistic.

Only if you call GEICO.

I'm going to be travelling around 25mph for stanard distance and 22mph for IM. If the saving is real the upgrade is going to happening, I'm going to struggle to get much more out of my training.

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http://www.tri-monkey.co.uk

first of all, if your'e on tubulars you're losing like 7 watts just for the butyl tubes in Conti tires

next, at any amount of yaw, you're losing time, both for the wheels and non-aero tires

10-20 is a good estimate. that's 3-6min over the course of an Ironman.

finally, don't forget the aero hierarchy:
1. position
2. clothing
3. wheels tires tubes as a system
4. helmet.
5. the totality of crap hanging off your bike
6. frame

how is your position, clothing, and helmet?

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Eric Reid AeroFit | Instagram Portfolio
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In the hierarchy of aero:

1: Position is as good as I think I can get and still run well from it.
2. Kiwami amphibian last season, looking at getting a Castelli aero offering for next, may be the San Remo trisuit with sleves.
3. Wheels PX 82/101
4. Lazer Tardiz
5. No crap, but need to tidy front end cabling a little (winter project)
6. Titanflex

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http://www.tri-monkey.co.uk

I subscribe to the aero advantages of 1. position 2. wheels 3. helmet but I don't see the extra aero benefits of clothing before 2/3 unless you are going from where MC Hammer Pants to a speedo.

Hilarious!!

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The Rat Snake:
A Tribute Race at Gilbert Lake State Park, Laurens, NY May 16 2015
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Very small changes to tuck cna have significant changes to aero. Head postion can makea pretty big difference. You ocudl be really low up front but you head is sticking up. From what i can gather, you're doing it right if you can just barely look all see clearly about 200y or so down the road and maybe 500y in your periphery. Forget looking a 1/2mi off into the distance. You head is too high.

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TrainingBible Coaching
http://www.trainingbible.com

I was referring to mc hammer pants! I loved that analogy!!

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The Rat Snake:
A Tribute Race at Gilbert Lake State Park, Laurens, NY May 16 2015
Follow the Rat Snake on Twitter

Make that wheel/tire/tube upgrade and get yourself a proven aero lid and I think you pick up 20 watts pretty easily (that Tardiz is no bueno).

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"One Line Robert"

I'm currently running PX 82/101 with conti competitions, will swapping to jet 9 and disc with latex tube and GP4000s or similar really save 15020W?

These guys are way over estimating.

Put a cover on the rear and get better tires. I'd look at narrow Conti track tires. The butyl tube is very thin in tubulars and is nowhere near a 7W penalty... maybe 2-3W. Or just get Vittoria Cronos. These should have lower rolling resistance than the GP4000.

So then we are left with the aero penalty of the front wheel which I doubt will be more than 5W at 25 mph even at high yaw.

I'm in a similar situation with a Flashpoint 80 clincher front wheel (old Zipp toroidal mold) and a 20mm Supersonic. If I could gain 5W with a new front wheel I'd do it in a heartbeat. I'm not convinced though.

+1. Those tires aren't very fast so you can get some speed by going with something better. I've never tested PX 82/101's, but they're pretty deep and can't be that bad. The disc will only make a difference if you have a crosswind, in which case a wheel cover will get you equal benefit for $90. My best guess would be the Jet 9 front would get you 1-2 watts over the PX82 in most circumstances (with the only possible exception being a massive crosswind).

So new tubs and a wheel cover. My previous helmet which I still have is a Giro Advantage II, The Tardiz is a lot more comfortable and much quicker to get on, I haven't seen any quantifiable change watts since making the swap, just a happier head.

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http://www.tri-monkey.co.uk

2-3 watts per tire/wheel though. Right? Or are the butyl tubes you're referring to not as much of a penalty as what others might be using in clinchers?

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"One Line Robert"

No... total. Tour tested a Supersonic with various tubes with an 85kg load at 35 km/hr.

The difference between a 50g butyl tube and the latex tube was 2.0W. With butyl tubes the loss is ~proportional to thickness. I think the tubes in tubulars are thinner than anything you can buy for clinchers.