recursive

Edit: photos on page 2

Short version: Why am I slow?

Long version:
Here's my data from my last 20k. I averaged a rather unimpressive 23.3mph for the sightly rolling course. I weigh 175 pounds and averaged 310 watts, giving slight emphasis to the climbs, and slight recovery on descents. I don't have the greatest threshold power, so that's about the best power I've ever produced for the duration.

Assuming only air resistance, and that power required varies with the third power of velocity, I calculate that I would have had to produce ~52% more power to match the ~26:30 of some of the fast guys. That's 470 watts, which is 5.9 w/kg. None of these guys are pro. I know there are a lot of assumptions in here, but it should be close enough for a rough estimate. Even analyticcycling.com tells me I should be going at least 3mph faster, but I don't necessarily put too much stock in that.

I'm still working on the engine, but I can't help but conclude my bike isn't very TT. What am I missing?
Race configuration saturday:

• TI frame w/ cages removed
• powertap w/ disc cover in back
• 36 spoke training wheel in front (bent my other wheel the day before)
• 23mm Michelin Pro2race tires
• profile design clip on aero bars set as close together as physically possible
• skinsuit
• aero helmet
• aero booties

I got beat by a team mate on a road bike with no aero equipment. Normally we seem to be evenly matched. Or am I actually just that slow?

tanhalt

Although that front wheel didn't help you much, I'm fairly certain the majority of the "gap" you're seeing is the result of poor body positioning. Basically, you're about as aerodynamic as the proverbial barn door!

For example, you and I are close to the same weight (I'm about 10 lbs lighter) and if I could average 310W for a rolling 20K TT I'm sure I'd be well north of 27mph average speed.

Your tires aren't bad...but there are significantly faster tire/tube combinations out there...

The good news is you've got a powertap to help you guide your positioning improvements. Do a web search on the "Chung Method" or "virtual elevation field testing" to learn more about how to use the PT to guide your changes.

Oh yeah...are you sure your PT was zeroed properly

Hocam

Try playing around with pacing strategies on analytic cycling and with the NP algorithm while using the topo map of the course. Split the course into multiple sections for each uphill and downhill, assign average grades and try different AP over each section. If you play around with the numbers in excel you can get a pretty good idea of how you can pace better with the same 310 watt NP.

Brian Ratliff

wind is mis-estimated in your calculations. 3mph faster would have given you your 26:30 time. The guys who went faster were both more aero than you and putting out more power. Also, it might be that course conditions changed during the TT. Those faster times might have been done earlier in the morning when winds are typically calmer.

recursive

Thanks for all the info everyone. As a quick note, yes my PT is zeroed and shows 0 watts when coasting.

waterrockets 

I weigh about the same as you and 310W would have me at closer to 25mph... on my road bike with clip-on aero bars and 64 spokes and 30mm aluminum clinchers.

I think you need to work on your aero position.

wfrogge

There is a study floating around on the net that says riding clip on aero bars in some cases is less aero than riding in the drops.

king-tony

A few observations:

First, as stated above, your position seems to be an issue. In full aero setup I can do sub 28 on a rolling course at nearly 200 lbs and 305 watts for a 20k. Not sure how much trouble you are willing to go through and without seeing you it would be difficult to make suggestions, but generally lower in the front will result in better results. Easiest way to get there on a road bike is to swap out the stem for something that can get you lower.

Your pacing strategy is not bad, you just did not execute fully from what I can tell. If you look at your graph page, it looks like you really drop your power at the top of the hills. To carry as much momentum as possible you have to pedal through the top until you get your speed back up. Then you can recover. Your biggest power spikes look to be followed by your lowest speeds.

Your power distribution is also pretty wide. You averaged 310, but were 350 on a lot of the hills and you spent 15 minutes over 313 watts and nearly 7 minutes over 357 watts. That's over 20% of the TT at 115% of your average which should already be about 105% of your ftp.

When looking at the hills (I assume they are hills because of the speed drops), they are short V's which you usually see when hitting something really steep. Are the hills that bad or was there a lot of wind or could you perhaps be losing momentum on the climbs - almost like you are letting off a little before the climb to mentally prepare to increase your power.

Your power is very respectable, looks to me like position changes and getting rid of the 15 mph sections would make you a lot faster. Something that has helped me on the latter is to take a rolling 3-4 mile section of road and ride it (sub threshold so you can repeat) different ways to see what is the fastest. Try doing +/- 10% on the climbs. Try holding the +10 30 meters past the top. Try it with a steady output all the way through, try hitting it hard in the low sections just before you start the hills, try hitting the top half of the roller harder etc. Record your times and you can pretty quickly see the fastest was around a course.

tanhalt

At the risk of turning this into Slowtwitch.com ...I think some pics of your position in use might be helpful to your cause...

Grumpy McTrumpy

My last flattish TT had me at 25.5mph with 243 watts average. I would be above 27mph with 310 watts on flats. Gently rolling would have me average around 24.5 mph with 240 watts.

Small aerodynamic improvements make a massive difference.

EDIT: one of the biggest improvements I have seen came from simply burying my head behind my fists a'la Landis/Levi

waterrockets 

True, it's not so simple as just clipping them on and going faster. My position is thoughtfully set up, and makes a huge difference vs. the drops. Position is still pretty close to this, but I'm adding real extensions with shifters and bullhorns. Card-carrying member of TT-4-Le$$.

YMCA

me too

We might live in a nice corner house, with a sweet Volvo and vacations to exotic locales with our teenage kids, but I refuse to spend any of those $$$$$$$ to save a minute at the local joe TT championship.

Heart, lungs, legs and clip-ons.

tanhalt

Me too...in fact, I've been dubbed by a teammate the "King of Cheapass Aero"

recursive

Oh. Oops.

Enthalpic

Really? I've seen your wheels.

waterrockets 

During the last drive with my wife in our Volvo, we were picking our next Hawaiian island to visit.

So, any shots of you on your rig?

recursive

I don't have photos. I won't for at least a day or two because the bikes in the shop getting the damage from the RR the day earlier repaired. I did the TT with only one functioning brake. But all you really need is zero. I will probably pick up a seatpost and some other bars while I'm at it.

But I'll try to get some before photos.

tanhalt

Right...and if I told you how little I paid for them, you wouldn't believe me

tanhalt

Not pics of the bike...pics of YOU on the bike. In your OP you seem fixated on equipment. I'm not sure if you're "hearing" what everyone is telling you...it's probably not the equipment, but more likely the relationship in space of your body relative to the equipment

DrPete 

Sounds like you need a better position and more time on the TT bike.

And FWIW, jamming your elbows together Zabriskie style isn't necessarily faster. I tried it and it made me miserable. If it's painful to ride on the aerobars, you'll either be weak or not ride the aerobars at all.

Here's my current, more comfortable setup, which has allowed me to drop the bars down a bit too...

recursive

Yes. That's what I understood. But I can't really take pics of me on the bike without the bike though...

tanhalt

Great. Just making sure. No pics from the event?

recursive

Only this one.

waterrockets 

Well, obviously we can't assume too much from that shot, but it looks low enough in the front that it would turn into a reasonable position. Pure speculation though

procrit

Pretty obvious why you went so slow.

Your front wheel is crooked and someone is hanging on the back of your bike.