Racing with a power meter. Link to my latest tt.

A light bike doesn't replace good fitness.

Moderator: Moderator Team

rchung
Posts: 97
Joined: Sat Jul 09, 2011 5:01 am

by rchung

Juanmoretime wrote:Last question until I post pictures or a video. I ran my H3 with a Bontrager aerowing 19 tt tire and Michelin latex tube, would it have been better to run my Zipp 808, not Firecrest, with a 20mm Continental Supersonic tire and a Michelin latex tube?

It's hard to beat the H3/Aerowing 19 at zero yaw. The place where the new FC Zipp 808 (and possibly 404) do better is at moderate non-zero yaw -- IIRC, they take a small zero yaw hit in return for better drag at non-zero yaw. I don't remember how the non-FC Zipps compare. You know what would be handy? Having an on-bike instrument to measure and record wind speed and direction. I'll bet people could do some cool things with that.

Machinenoise
Posts: 141
Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

Cheers for that wheel information rchung! What tub do recommend for a h3 then? Currently on a vittoria cx-tt 21.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



rchung
Posts: 97
Joined: Sat Jul 09, 2011 5:01 am

by rchung

Machinenoise wrote:Cheers for that wheel information rchung! What tub do recommend for a h3 then? Currently on a vittoria cx-tt 21.

http://www.biketechreview.com/tires_old ... g_rev9.pdf

Privateer
Posts: 360
Joined: Thu Feb 03, 2011 2:28 pm

by Privateer

Juanmoretime wrote:Feel free to share your races for some feedback on this post!


Here's my latest TT, yesterday evening: http://connect.garmin.com/activity/176958413

For context- I'm 38 years old, 72kg and a max HR of about 165-170.

I was pretty happy with my average power considering that I've just finished a big block of endurance training with very little speed work (preparing for an ultra). The average speed was okay too. I thought it might be a little slower because I used my ultra bike which has the bars set quite high compared to my TT bike.
Image

Now I'm wondering whether it's any slower at all (or if I can have my aero cake and eat it in comfort :wink: ). Does anyone know an easy way to estimate CdA? I have data from TTs on my TT bike. My power is about the same, but they're not over the same course.

What I'm not happy with was a slight fading of my power and drop in cadence early on the second lap.

... and here's a gratuitous pic of the scenery where the race was (Bavois, Switzerland) :mrgreen: :
Image

rchung
Posts: 97
Joined: Sat Jul 09, 2011 5:01 am

by rchung

Privateer wrote: Does anyone know an easy way to estimate CdA?

Depends on what you mean by "easy," and the degree of precision you need. The easiest way is in a wind tunnel; precise, but expensive.

There are various ways you can estimate your CdA with a power meter. Some are more precise than others. If you have a flat calm road, the easiest but not terribly precise way is this:

Image

If you don't have access to a flat venue but can find something traffic-free and protected from the wind, you can use the virtual elevation method with an appropriate test protocol, which is what is used by Golden Cheetah's Aerolab module. Another implementation can be found here: http://www.cyclingpowermodels.com/CdAEstimation.aspx Click on "About" to read an explanation.

Machinenoise
Posts: 141
Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

As promised a few details of some of my races/intervals. First images is of a 50 mile TT from 2010 with slightly dodgy pacing and a puncture. And the other image added today is a 20min hill climb interval. Image
Image


A CdA of 0.21 is pretty impressive rchung! Am doing some testing at the moment to reduce mine, being 6'1" with broad shoulders doesn't help. I think I've got down to 0.23 with the latest changes (to a Levi style mantis position), I just have to find out if i can pedal at the same output in that position!

Club TT on Wednesday night for more data collection so will post that too.

mrlobber
Posts: 1928
Joined: Sat Oct 23, 2010 9:36 am
Location: Where the permanent autumn is

by mrlobber

Scratching my head a little here. Don't have a power meter on my TT bike, but have one on my road bike, and the possible conclusions are interesting or maybe plain wrong :D

The TT in question was done on a "squared circuit", 2 laps of 6km each, sea level, sunny evening but around 10 C of temperature only, pretty slow wind and many trees around, so I'd guess the wind impact was quite minimal, certainly I didn't feel much.

For the 12km, I produced an average speed of 39km/h which was 2.3km/h improvement from my road bike testing of the same circuit last year. In TT, my HR was pretty close to max sustainable for that length of the interval, and therefore I'd guess the power as well. Now the kicker - on my road bike I could produce approx 300W for the duration, so I'd guess, even if my TT position was pretty uncomfortable (which personally doesn't seem to be the case), I should have put out at least 270W.

From the power models, producing 270W at sea level for 39km/h would solve approx for 0.35 CdA which seems to be quite a high value for a TT bike. For instance, Privateers TT above for his speed and power solves for CdA of 0.28. Too rough of a calculation , do I have the most "unaero" TT position ever :D, or something else not taken into account? Will post a pic of me from the finish line of the TT in question later.
Minimum bike categories required in the stable:
Aero bike | GC bike | GC rim bike | Climbing bike | Climbing rim bike | Classics bike | Gravel bike | TT bike | Indoors bike

Machinenoise
Posts: 141
Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

mrlobber wrote:Scratching my head a little here. Don't have a power meter on my TT bike, but have one on my road bike, and the possible conclusions are interesting or maybe plain wrong :D

The TT in question was done on a "squared circuit", 2 laps of 6km each, sea level, sunny evening but around 10 C of temperature only, pretty slow wind and many trees around, so I'd guess the wind impact was quite minimal, certainly I didn't feel much.

For the 12km, I produced an average speed of 39km/h which was 2.3km/h improvement from my road bike testing of the same circuit last year. In TT, my HR was pretty close to max sustainable for that length of the interval, and therefore I'd guess the power as well. Now the kicker - on my road bike I could produce approx 300W for the duration, so I'd guess, even if my TT position was pretty uncomfortable (which personally doesn't seem to be the case), I should have put out at least 270W.

From the power models, producing 270W at sea level for 39km/h would solve approx for 0.35 CdA which seems to be quite a high value for a TT bike. For instance, Privateers TT above for his speed and power solves for CdA of 0.28. Too rough of a calculation , do I have the most "unaero" TT position ever :D, or something else not taken into account? Will post a pic of me from the finish line of the TT in question later.

:|
Using this modeller http://www.cyclingpowermodels.com/Power ... arios.aspx
(Only disadvantages to this site are the inability to change the pressure and temp figures, which are too favourable for the uk! not many low pressure 20 degree days over here!)

I get privateers to be roughly 0.25-0.24 ignoring elevation changes on the overall power average.

and for yourself assuming 270w we get 0.28-0.29, Room for improvement certainly but that's what this game is about. It takes me weeks of turbo+road training on the TT bike to acclimatise to the position or to positional changes to even come close to replicating my road power on the TT bike.

Maybe try swapping the PM over to the TT bike for some testing?? I have to use my Powertap on box section rim for testing which is a significant compromise over a disc, but the accurate information is essential.

One question, I'm assuming the squared course means it has roughly 4 corners, or is a loop, as slowing to corner and lack of pedalling can have large impacts on the figures too. 8 corners would have a large effect on final results.

Machinenoise
Posts: 141
Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

Evening 10mile TT on training wheel set-up nice 28mph average 332W average. 21:24
Several lessons, 1.started way too hard, 2. continued too hard for the first section, 3. should have taken the first turn @5mins faster. 4. need the 11 sprocket on the Disc going down the hill at half way! maybe my 56 chainring too.... spinning at 110rpm after the hill ruined me a bit and made it difficult to maintain power output. 5. disappointed with the drop off in the last 4mins. Really started to struggle, and really dragged the average down. Suspect I lost a fair amount of time in the uphill drag to the finish!
Image
5 second smoothing

Maybe looking at a long 20min 10 with the disc and tri-spoke back on the bike??

Machinenoise
Posts: 141
Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

Nice one Juanmoretime!
Loving the absolute straight flat road you've got!
Numbers say you paced that pretty well! av274 NP 274!
Would say the start and turn might be a bit too anaerobic 743w at the turn is quite aggressive. But you've gotta work things like that out by feel.

Intensity Factor suggest there might be a little more in the tank. You can probably get up to 1.0+ in a ~20min effort. as 1.0 should represent the maximum effort you can physically sustain for 1hour.

beardking
Posts: 257
Joined: Thu Dec 29, 2011 11:22 pm

by beardking

here are my two time trials from this week. these are my 5th and 6th time trials and my second and third time using clip on bars so I'm still pretty new to this. I was riding a caad10 with fulcrum racing 7's

wednesdays 10 mile TT
Image
Image
http://app.strava.com/activities/9731279
I got first place and finished with a time of 23:46 a PB and this first time I've been under 24 minutes.
I didn't put out anywhere near as many watts as I would have liked though. didn't do a test ride with the TT bars on and I'd put them on wrong and didn't notice till it was too late. seems I had them at a different angle than my previous ride with them and they were tilted down too close to my knees.
also not sure about my pacing :oops: the course was very up and down and i had to reach off the clip ons to shift so I was trying to do that as little as possible

thursday night 9.2mile hilly course
Image
Image
http://app.strava.com/activities/9807905
I got 21:43 and finished third 31 seconds behind the winner.
moved the bars away from my knees and straight away I felt better and my power was 30 watts higher than the previous night.
again the route was lumpy, might have gone a bit too hard on the climb at the start but my heart rate rises steadily through the TT.

also I should have probably done a warm up I did the TT pretty cold

jo.k
Posts: 196
Joined: Fri Jan 09, 2009 11:39 pm
Location: Norway

by jo.k

TT last night, 30km, relatively flat. Started a little too hot for the first 10k, and really struggled to maintain speed and power in the headwind on the way back. Also a little too few hours spent on the TT bike this season. Changing the rear wheel after the race resulted in all sorts of cramps :(

http://connect.garmin.com/activity/186422531" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

jo.k
Posts: 196
Joined: Fri Jan 09, 2009 11:39 pm
Location: Norway

by jo.k

Thanks, I was quite happy with the performance after all. My first TT with a power meter, did not quite know what actual FTP on the TT bike was. Will use the analysis from this race to plan my next big TT (national championship in two weeks, 50km). Finished 21th last year, will be pleased to repeat that this year! :)

woz9683
Posts: 233
Joined: Sun Jul 11, 2010 6:58 pm
Location: MS, USA

by woz9683

Juanmoretime, impressive!

Thought I'd throw one of my little short ones in here.
Image
My first win in a TT! Cat 4 stage race in New Orleans this past weekend. 3miles into a bit of a headwind on a flat road. This was a few hours after a 65mile RR in terrible weather, so not too bad. The pic came out a little small, but 336w, 28.3mph. I broke it up into 1min increments to see how level I was. Obviously started a little hard, averaged 400w for the first minute, a lot of that was just my kick off the line and my first 30sec settling, but it hurt me a bit in the middle. Saved a little for the last mile, passed my 30sec man about 200m from the line and being able to swing around him gave me the win! My time was 6:36.3s..... second place was 6:36.6s :twisted: Very close!

woz9683
Posts: 233
Joined: Sun Jul 11, 2010 6:58 pm
Location: MS, USA

by woz9683

Thanks! Yes, really enjoying mine as well. I think I must be a little shorter in the leg than you are, my saddle is a good bit lower, and I got an adjustable stem to get lower on the front as well. I probably need to post a new picture or two.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Post Reply