Help me understand my Power - why aren't I faster?

Jul 4, 15 8:45

Post #1 of 20 (4087 views)

85 hilly, curvy miles yesterday (IMWI loops). Numbers looked like this:

FTP: 257
Avg power: 171
NP: 182
IF: .708
TSS: 252.4
VI: 1.06

Avg speed: 16.7mph

If I continue with this speed another 25 miles I'd have an IM split of around 6:30. VI is high, and while I had a decent 6 mile run-off after the bike I think I need to be a bit more conservative. Anyway - if I plug these numbers into Best Bike Split, it indicates my average speed should have been almost 19mph, with a <6:00 split. Looking at this table from Friel doesn't make a lot of sense (I wonder if it doesn't account for IMWI's unique terrain?), but still seems to indicate this IF and TSS should be better than 6:30. http://home.trainingpeaks.com/...-meter-in-an-ironman

What am I missing? Shouldn't I have been faster? Why the huge disconnect between reality an BBS? What can I realistically do to be faster with similar power numbers?

Other details, FWIW:

6'0", 185 lbs
2009 Trek TTX Equinox 9.0
60mm front
Disc rear
4000S II tires
latex tubes
Specialized Evade helmet
BTA and behind the saddle bottles, aero bottle on down tube with spare kit.
Aero position as much as possible on flat sections. Power never above FTP on the hills. I feel like I rode smart.

Feels like I'm about as aero as I can be - not sure I have any free speed I'm not taking advantage of.

Thanks for any advice or insights!

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 9:01

Post #2 of 20 (4054 views)

nitrox wrote:

8
Thanks for any advice or insights!

Are you absolutely sure you don't resemble one of these?

Genetics load the gun, lifestyle pulls the trigger.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 9:08

Post #3 of 20 (4037 views)

Quote:

6'0", 185 lbs

Seems like low power numbers for a guy your size.

For reference I'm 5'9 and 25lbs lighter than you (30-35 if I were in IM shape) and my FTP is 252. And I don't consider myself to be that great a cyclist.

Re: Help me understand my Power - why aren't I faster? [logella] [ In reply to ]

Jul 4, 15 9:31

Post #4 of 20 (3995 views)

What were you wearing? What's your position like? A ton of speed can be gained (or lost) with a real good or pretty poor position. Do you have a picture of your bike position?

As another reference point, on a pretty hilly ride that I just did (110 miles w/8500 ft of elevation) I averaged 20 mph on 233 watts. I'm 6' 168 lbs.

Blog: http://262toboylstonstreet.blogspot.com/
https://twitter.com/NateThomasTri
Coaching: https://bybtricoaching.com/ - accepting athletes for 2023

Re: Help me understand my Power - why aren't I faster? [sciguy] [ In reply to ]

Jul 4, 15 9:45

Post #5 of 20 (3970 views)

sciguy wrote:

nitrox wrote:

Thanks for any advice or insights!

Are you absolutely sure you don't resemble one of these?

Or maybe he's using a Stages.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 10:16

Post #6 of 20 (3908 views)

nitrox wrote:

Aero position as much as possible on flat sections.

Busted! Unless you're going 8mph uphill you should stay in aero.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 10:48

Post #7 of 20 (3832 views)

I agree with logella. For 185 bills, your FTP is lower than I would expect. I'm a few inches taller at 6'3" and weight almost 200. FTP is 315. BUT on a hilly course, then I wouldn't expect to knock out a large average speed, especially on a solo endurance ride. Are you testing FTP indoors or outside? Road or tri (mine is higher when testing on road bike). What test are you using to calculate. There are so many variables.

Human Person

Re: Help me understand my Power - why aren't I faster? [trismitty] [ In reply to ]

Jul 4, 15 12:05

Post #8 of 20 (3729 views)

Hmm. FTP Seems to is a reasonable culprit? I do a 20 minute all-out on the same stretch of road once a month. 30 minute warm up. Maybe I just suck at the bike.

In Reply To:

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 14:20

Post #9 of 20 (3588 views)

Are you saying that you're putting those stats into Best Bike Split for the IMWI course? If so, that's shocking that their number would be so much higher...are you sure you entered everything correctly? BBS is typically pretty darn accurate. With that being said, people here aren't going to sugar coat it...your bike needs a lot of work and hopefully your weight will come down a bit with the training which will help on the hilly course.

Is your goal 65-70% of FTP? That is definitely on the lower end of the range but obviously if your bike fitness isn't there that probably makes sense. If I were you, I would try some of your longer rides at higher % of FTP (maybe 70-80%) to see how your body responds with the run afterwards...this is training, if you blow up, that's ok!

Now, if you're just hoping to finish none of this really matters and you should go with what feels comfortable and makes the race enjoyable instead of miserable.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 16:02

Post #10 of 20 (3456 views)

I can answer half of your question - You can't use Friel's table to project bike time. It isn't designed for that and you can't use it to work backwards that way.

Friel's table doesn't project finish time from IF/TSS, but rather it estimates TSS bases on a give time and IF and from that concludes if you left something on the bike or overcooked.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 16:23

Post #11 of 20 (3417 views)

A few things....

Your FTP is just over 3W/Kg which is pretty average, not terrible but not great.

VI 1.06 isn't that bad for a very hilly ride but you didn't really define hilly.

The huge disconnect between your math and BBS is most likely you are grossly overestimating how aero you are and you are entering in a Cda that is lower than what you actually are. "Aero position as much as possible on flat sections" indicates you sat up a lot. Yes that could make that huge of a difference.

I'd suspect fit and staying in an aero position as the biggest culprit to start.

Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 17:24

Post #12 of 20 (3349 views)

Something is wrong with your calculations on best bike split.
My FTP is 209, but I am small at 5'6" and between 125-130 lbs. That puts me around 3.5 watts/kg vs around 3 for you. According to best bike split for me, I should be averaging around 18.5 mph with a finish time of 6 hours and about a minute. So you shouldn't be able to go faster than me with a lower watts/kg.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 20:58

Post #13 of 20 (3122 views)

Did you just use drop downs for CdA or did you calculate (or estimate 0 yaw and plug that in). I find that often people myself included are guilty of thinking we are way more aero than we actually are. Any photos of your position front and side would help a little, also at what speed and gradient do you get out of aero (thinking of exposingn this variable as a setting)

-----------------------------------------------------------------
Founder: BestBikeSplit
Amazonian

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 4, 15 21:23

Post #14 of 20 (3094 views)

I'm not a power expert, so I'm not sure if BBS takes this into account, but could it be you are not riding on race day? All those slowing for turns, waiting for traffic, stopping (or at least slow rolling) at stops signs. I would guess that would throw any BBS numbers off from race day. I had ridden the course several times before my IMWI and based on my training times I was thinking I'd be in the 6:25 range. Ended up 6:04 and I took it super easy on the bike. I attribute that increase in speed to being able to roll through all things you would normally slow or stop for (and maybe a little bit of tapper helped?).

Again, I could be wrong and if I am I'd be happy to hear why. I didn't have PM at the time and am looking to get one soon, so this could be educational for me.

Re: Help me understand my Power - why aren't I faster? [nitrox] [ In reply to ]

Jul 5, 15 4:58

Post #15 of 20 (2886 views)

Your power meter could be returning higher values than actually producing

My bestbikesplit predictions were way off (I was on the slow side) for quite a while, a full season on every course

I switched to quarq for race wheel purposes and the power levels on the quarq were wayyy lower. I didn't know which power meter to believe. So I did the full hanging weight calibration with the quarq and the factory settings were right.

i had to lower my FTP by 25% in the end.

Now my bestbikesplit time on my last 70.3 was within a minute of actual

I had no idea that my powertap was so far off, I had nothing to compare against.

Last edited by: vancity: Jul 5, 15 4:59

Re: Help me understand my Power - why aren't I faster? [vancity] [ In reply to ]

Jul 5, 15 5:52

Post #16 of 20 (2813 views)

vancity wrote:

Your power meter could be returning higher values than actually producing

My bestbikesplit predictions were way off (I was on the slow side) for quite a while, a full season on every course

I switched to quarq for race wheel purposes and the power levels on the quarq were wayyy lower. I didn't know which power meter to believe. So I did the full hanging weight calibration with the quarq and the factory settings were right.

i had to lower my FTP by 25% in the end.

Now my bestbikesplit time on my last 70.3 was within a minute of actual

I had no idea that my powertap was so far off, I had nothing to compare against.

You could've done the same hanging weight test.

[Edited to add:] That said, I can't recall the last time I saw a PT regularly reading high -- when it fails, it usually reads low. There was an interestingly (in)famous case of a PT on a trainer that read high but that's cuz the rider wasn't zeroing properly.

Last edited by: RChung: Jul 5, 15 8:08

Re: Help me understand my Power - why aren't I faster? [RChung] [ In reply to ]

Jul 5, 15 12:09

Post #17 of 20 (2628 views)

RChung wrote:

vancity wrote:

Your power meter could be returning higher values than actually producing

You could've done the same hanging weight test.

[Edited to add:] That said, I can't recall the last time I saw a PT regularly reading high -- when it fails, it usually reads low. There was an interestingly (in)famous case of a PT on a trainer that read high but that's cuz the rider wasn't zeroing properly.

Yep! absolutely right -- I wasnt familiar with the process though until quarq and the qalvin app were in my hands.

I had no suspicions about my powertap, i knew my bestbikesplit.com times were off, but i didnt think much off it (i figured they werent that good at predicting! lol...).

Once i got the quarq though, thats when i knew something was up with either the quarq or the PT.

I was very diligent with zeroing and my values were good

Re: Help me understand my Power - why aren't I faster? [vancity] [ In reply to ]

Jul 5, 15 13:07

Post #18 of 20 (2570 views)

I have a similar problem but not as bad your numbers. I'm usually 0.5 mile slower than BBS predictions. I too have a stages PM and I think they read high.

Re: Help me understand my Power - why aren't I faster? [hubcaps] [ In reply to ]

Jul 5, 15 13:35

Post #19 of 20 (2523 views)

hubcaps wrote:

Something is wrong with your calculations on best bike split.
My FTP is 209, but I am small at 5'6" and between 125-130 lbs. That puts me around 3.5 watts/kg vs around 3 for you. According to best bike split for me, I should be averaging around 18.5 mph with a finish time of 6 hours and about a minute. So you shouldn't be able to go faster than me with a lower watts/kg.

Watts/kg are not the sole factor in determining bike splits though, as this thread is trying to demonstrate. Especially with just 3000ft of climbing.

Re: Help me understand my Power - why aren't I faster? [snaaijert] [ In reply to ]

Jul 5, 15 15:21

Post #20 of 20 (2438 views)

Yes Watts per CdA (weighted for yaw) is probably a better indicator for most Tri / Flat TT Courses. Off course if you have worse Watts/Kg and you sit up quite a bit it won't matter as you will get negatively hit with both. Somewhere I have some charts on impact of +-10 pounds versus a .02 reduction in CdA on a typical IM course. While that reduction in CdA is pretty hard at the point end of the spear it's much easier for mid pack age groupers (like myself) and can make a pretty drastic difference. I'll see if I can find it to post.

-----------------------------------------------------------------
Founder: BestBikeSplit
Amazonian

Our Partners

transition-DOT-area-AT-slowtwitch-DOT-com

Advertise with us

©1999-2024 Slowtwitch, Inc., and Slowtwitch.com
Reproduction of material from any Slowtwitch.com page
without written permission is strictly prohibited.