Jump to content
Sign in to follow this  
fishboy

Getting aero and pacing for TristanP

Recommended Posts

Well after 6-8 months of testing on TristanP we've managed to get his drag down a heap ... to the point he's added about 2.5 kmh of speed at 40 km/hr running on the same input power.

This is in a position that we know he can sustain for IM, which is quite impressive, and bodes well for Port this year.

 

It's been a bit of an eye opener for Tristan, to the point he's been total believer in the whole aero thing for some time, and has now started doing aero testing through his shop in addition to the bike fitout. (You need to BYO power meter at the moment, more details here).

 

Here's the graph, you can see each subsequent test shifting the data curve further and further to the right. The tests were pretty much in sequence from left to right - we kept getting slightly better and better as we worked out things to improve on, with a big jump at the end.

 

The last thing we tried, which delivered the absolute best aero, was some tricko stuff I developed over a couple of years R&D ... it seems it works on other people too, which is cool.

 

NB. At the moment we've left the actual watts off the Y axis (and shifted the zero point a bit), after Port Tristan plans to post the full data.

 

tristanP.gif

 

The other thing I managed to do this weekend was upgrade my power calculator so that it can back calculate speed, Crr, CdA, and slope in addition to watts (it used to just be able to calculate watts). So basically now you can use a Crr of 0.005 which is typical for normal road conditions and if you know your watts and speed you can work out your own CdA (drag) quite easily.

 

To do this:

 

Use the default air density (it's a rough guide).

Enter the mass of you and your bike and all your gear (closest kilo or two is OK, this affects rolling resistance mostly so doesn't affect CdA too much)

Enter 0.005 for the Crr (Rolling resistance).

Enter 0 for the slope.

Enter the speed (use the convertor to get speed to metres/sec).

Leave the CdA blank.

Enter the watts.

Press calculate.

 

It'll spit out a table of watts, split times and a graph for you, as well as the all important CdA.

 

For those people doing Port with power, it may assist in being able to predict a split time based on your input power you're hoping to maintain. I've found it to be accurate over shorter distances (up to 40km) to within a few seconds, but I'd be interested hear from anyone as to how their prediction stacked up vs their actual.

 

Enjoy.

Share this post


Link to post
Share on other sites

Hi Fishboy,

 

Like your work. Had a go on your calculator with some race data from Shepp, Busso and Torquay. Shepp and Busso line up pretty well (dead flat courses) and give me a cda in the 0.23-0.24 range. Torquay gives me 0.277. From the SRM it measured the change in elevation at Torquay at 114m so that must have an effect. Similarly I would have stood out of the saddle more at Torquay due to the nature of the course compared with the other two. Bike set up was exactly the same for all three rides, power level at Torquay was ~8% higher than Shepp and 14% higher than I rode at Busso. Got a power range I'm looking to ride at Port but not sure how I could use your calculator to estimate a bike split with the 600m or so of altitude gain that will go on at the same time?

Share this post


Link to post
Share on other sites
Hi Fishboy,

 

Like your work. Had a go on your calculator with some race data from Shepp, Busso and Torquay. Shepp and Busso line up pretty well (dead flat courses) and give me a cda in the 0.23-0.24 range. Torquay gives me 0.277. From the SRM it measured the change in elevation at Torquay at 114m so that must have an effect. Similarly I would have stood out of the saddle more at Torquay due to the nature of the course compared with the other two. Bike set up was exactly the same for all three rides, power level at Torquay was ~8% higher than Shepp and 14% higher than I rode at Busso. Got a power range I'm looking to ride at Port but not sure how I could use your calculator to estimate a bike split with the 600m or so of altitude gain that will go on at the same time?

I would be careful using the power data from Torquay due to the wind as well as the crap road conditions. I know that my power to speed output there was not directly in line with expectations based on known drag data.

 

The 600m of gain at Port will put things out a little on the calculator I am sure, but it is relatively flat still. I actually didnt think its was 600m on the new course anyway, but not too much less.

Share this post


Link to post
Share on other sites
I would be careful using the power data from Torquay due to the wind as well as the crap road conditions. I know that my power to speed output there was not directly in line with expectations based on known drag data.

 

The 600m of gain at Port will put things out a little on the calculator I am sure, but it is relatively flat still. I actually didnt think its was 600m on the new course anyway, but not too much less.

I think you're right with the comparison - there was little in the way of wind impact at Shepp and Busso whereas Torquay was all over the place.

 

I was using the 600m from somewhere else on here (so it must be true!). Assuming that it is, then that equates to a slope across the course of ~0.003% which, in my case, increases my predicted bike time under perfect conditions by around 17mins. Without putting the time out there its about 5mins quicker than I was thinking it should be.

Share this post


Link to post
Share on other sites
The man was already motoring - so what did you change to get him 2.5km/hr quicker?

 

4 sets of wheels, 3 helmets, seat/arm height ratio changes, forearm angle changes, elbow width changes and special fishboy add on at the end.

 

Helps if you own a bike shop and you can afford to swap that stuff over quickly!

Share this post


Link to post
Share on other sites
I think you're right with the comparison - there was little in the way of wind impact at Shepp and Busso whereas Torquay was all over the place.

 

I was using the 600m from somewhere else on here (so it must be true!). Assuming that it is, then that equates to a slope across the course of ~0.003% which, in my case, increases my predicted bike time under perfect conditions by around 17mins. Without putting the time out there its about 5mins quicker than I was thinking it should be.

 

Yeah if there is a lot of elevation change, and you are out of the saddle a lot, the CdA will be comparatively higher...

 

You can take a small chunk of data eg around 1 min with constant speed and watts on level ground and see what that throws out.

 

IM times are a bit hard to predict really accurately, any time you are out of aero, sitting up, stretching etc it can affect your CdA and the "likely" time based on the estimate of your drag.

Share this post


Link to post
Share on other sites
Yeah if there is a lot of elevation change, and you are out of the saddle a lot, the CdA will be comparatively higher...

 

You can take a small chunk of data eg around 1 min with constant speed and watts on level ground and see what that throws out.

 

IM times are a bit hard to predict really accurately, any time you are out of aero, sitting up, stretching etc it can affect your CdA and the "likely" time based on the estimate of your drag.

Always going to be harder, but from memory we were within 5 min from my Port time last year... In the grand scheme of things thats pretty bloody close

Share this post


Link to post
Share on other sites

Given my newfound interest in power and all things bike speed I thought I'd do a bit of malicious (not really! :lol: ) stalking and came up with a few questions.

 

Tristan's sprint distance bike improved by a whopping 2 minutes over 20km from GTS Race 2 to GTS Race 6.

Did you record the data for that? How much of that was due to improved cda, improved fitness or other factors (eg was course more technical/winds etc)

 

A bonus question. On the the final race Tristan was 2 minutes faster than Fishy on the bike (Fishy's ride was still pretty impressive!) - what can you attributed this to in terms of power, cda and fitness?

 

Anyway, love your work guys - great to see some real objectivity into the black art of TT'ing. :lol:

Share this post


Link to post
Share on other sites
Given my newfound interest in power and all things bike speed I thought I'd do a bit of malicious (not really! :lol: ) stalking and came up with a few questions.

 

Tristan's sprint distance bike improved by a whopping 2 minutes over 20km from GTS Race 2 to GTS Race 6.

Did you record the data for that? How much of that was due to improved cda, improved fitness or other factors (eg was course more technical/winds etc)

 

A bonus question. On the the final race Tristan was 2 minutes faster than Fishy on the bike (Fishy's ride was still pretty impressive!) - what can you attributed this to in terms of power, cda and fitness?

 

Anyway, love your work guys - great to see some real objectivity into the black art of TT'ing. :lol:

It is possible with careful analysis to attribute differences to each of the major things that matter in a TT:

course profile and environmental conditions

power output

CdA & Crr improvements

pacing

 

but it takes some time to pull it apart. I gave an example in this blog post.

 

I just got great news this morning that one of my clients won the Pan American TT championships overnight and is now selected to go to world championships. In his case we focused on all elements to develop the incremental gains. This included time in the wind tunnel amongst other things.

Share this post


Link to post
Share on other sites
Thanks Alex. Must be nice to know that your work is actually assisting many people to go quicker!

It's actually getting into it and doing the practical stuff that is what's so cool. You do that well.

 

You are going to love Aerostick when it comes out.

 

Once all is confirmed (I will have first unit) and I have done all the preliminaries and testing, I will look to do a session in Melbourne at some stage. Perhaps you'd like to work with me on that.

Share this post


Link to post
Share on other sites
Given my newfound interest in power and all things bike speed I thought I'd do a bit of malicious (not really! :lol: ) stalking and came up with a few questions.

 

Tristan's sprint distance bike improved by a whopping 2 minutes over 20km from GTS Race 2 to GTS Race 6.

Did you record the data for that? How much of that was due to improved cda, improved fitness or other factors (eg was course more technical/winds etc)

 

A bonus question. On the the final race Tristan was 2 minutes faster than Fishy on the bike (Fishy's ride was still pretty impressive!) - what can you attributed this to in terms of power, cda and fitness?

 

Anyway, love your work guys - great to see some real objectivity into the black art of TT'ing. :lol:

The last piece of the puzzle as far as the aero stuff goes was not on the bike for the ride at GTS race 6, so my CDA was actually less than what it is currently. I would have been about another minute or so quicker again if I had that as well at the time... The interesting bit is that that piece of the puzzle was strapped to Fishboy's bike... I will let you do the maths, but the time difference at the last race is purely due to my FTP being so much higher than his as he was a lot more aero than I was at the time.

 

As far as the difference between race 2 and 6, my position between these races didnt change a whole heap, my available power went up considerably. There was about 70 watts difference in the average power for the 2 rides.

 

Since racing Roth last year in July, my FTP has increased by about 70 watts as well, so a lot of the increase is training related. Most of the aero savings were completed before race 1 of GTS. Aero savings are still a massive piece of the TT puzzle, but most people with a power meter will still get more benefit from improved training techniques that will increase FTP. The aero stuff just gets the most out of the available power.

Share this post


Link to post
Share on other sites

Fishmonster - without getting too technical, could you give a bit of insight into how your protocol accounts for differnt yaw angles (I'm guessing the most common being around the 15-20 degree mark). Reason for the question is that I get the real world testing would be very reliable in still conditions, but not sure how you get a repeatable result when its a bit windy (which is the most common condition).

Share this post


Link to post
Share on other sites
Fishmonster - without getting too technical, could you give a bit of insight into how your protocol accounts for differnt yaw angles (I'm guessing the most common being around the 15-20 degree mark). Reason for the question is that I get the real world testing would be very reliable in still conditions, but not sure how you get a repeatable result when its a bit windy (which is the most common condition).

You are right Otter... When doing the testing we would complete the tests on days where the conditions are as still as possible. It is a restriction of the model but is a restriction that when worked around by selecting optimal times for testing is still a heap cheaper than going to a wind tunnel.

 

It would be pretty pointless to take data that you collected on Beach Rd coming back from Mordi with a 50km Southerly and expect an accurate result... You would however be very bloody aero if you did use such data ;-)

Share this post


Link to post
Share on other sites
Fishmonster - without getting too technical, could you give a bit of insight into how your protocol accounts for differnt yaw angles (I'm guessing the most common being around the 15-20 degree mark). Reason for the question is that I get the real world testing would be very reliable in still conditions, but not sure how you get a repeatable result when its a bit windy (which is the most common condition).

 

Is yaw angle how far open your mouth is while riding? :lol:

Share this post


Link to post
Share on other sites
Is yaw angle how far open your mouth is while riding? :lol:

Directly correlated to the number of bugs that you swallow... Its a means of calculating the reduction in calories that you need to consume when riding based on said bugs.

Share this post


Link to post
Share on other sites
Are there any before and after shots that you are both willing to share?

 

That is really up to TristanP.

Share this post


Link to post
Share on other sites
You are right Otter... When doing the testing we would complete the tests on days where the conditions are as still as possible. It is a restriction of the model but is a restriction that when worked around by selecting optimal times for testing is still a heap cheaper than going to a wind tunnel.

 

It would be pretty pointless to take data that you collected on Beach Rd coming back from Mordi with a 50km Southerly and expect an accurate result... You would however be very bloody aero if you did use such data ;-)

 

I've found that even when windy, if the wind is pretty constant direction and speed, and you do the test on a round circuit eg velodrome, your CdA measured estimate is still actually very close. It is usually slightly LOWER than your calm CdA measurement as (I think) you get more lift from disks and aero wheels in varying yaw than at 0 yaw.

 

With aerostick, you should be able to get the second by second windspeed at the front of the bike which should remove the limitation of testing on non-windy days, and allow you to get more accurate CdA in windy conditions. It should also mean you can test bits of gear at certain yaw if you can ride constant enough speed for long enough you should be able to bin all the data into yaw "buckets" and work out what works better.

 

Yes, Alex, if you make it down here with an aero stick, love to see it in action. Time for another beer or so too I reckon.

Share this post


Link to post
Share on other sites
You are right Otter... When doing the testing we would complete the tests on days where the conditions are as still as possible. It is a restriction of the model but is a restriction that when worked around by selecting optimal times for testing is still a heap cheaper than going to a wind tunnel.

A restriction that will be removed with use of Aerostick.

Share this post


Link to post
Share on other sites
Are there any before and after shots that you are both willing to share?

 

 

That is really up to TristanP.

 

come on Tristan - lets see the before and after shots please.

Share this post


Link to post
Share on other sites
As far as the difference between race 2 and 6, my position between these races didnt change a whole heap, my available power went up considerably. There was about 70 watts difference in the average power for the 2 rides.

 

Since racing Roth last year in July, my FTP has increased by about 70 watts as well, so a lot of the increase is training related.

I appreciate that this thread is largely focussing on aero improvements.........................

 

but what on earth did you do to get a 70W improvment in FTP?????????????

 

Extremely impresssive - but am curious to know how you did it?

 

TGL

Share this post


Link to post
Share on other sites
I appreciate that this thread is largely focussing on aero improvements.........................

 

but what on earth did you do to get a 70W improvment in FTP?????????????

 

Extremely impresssive - but am curious to know how you did it?

 

TGL

 

;-) We spent a long time this season trying to smash each other... Lots of hard intervals at distances varying from 1km to 20km, hill work and going long. My sustainable power increased 30% between Sept and Dec, peaked in Jan, and declined lightly through the rest of the season after that. Use it or lose it basically. Tristan however has continued to push himself and is really starting to see the results of all those hard yards. You know when you've smashed out 13 or 14 5km intervals on the velodrome that you are starting to see improvement ...

Share this post


Link to post
Share on other sites
;-) We spent a long time this season trying to smash each other... Lots of hard intervals at distances varying from 1km to 20km, hill work and going long. My sustainable power increased 30% between Sept and Dec, peaked in Jan, and declined lightly through the rest of the season after that. Use it or lose it basically. Tristan however has continued to push himself and is really starting to see the results of all those hard yards. You know when you've smashed out 13 or 14 5km intervals on the velodrome that you are starting to see improvement ...

Mate - well done. That is a great effort. I've never even contemplated doing something like that!

 

TGL

Share this post


Link to post
Share on other sites
come on Tristan - lets see the before and after shots please.

I will try and post something tomorrow... I dont have any online at the moment other than Facebook and I dont think I can get a URL like from there

Share this post


Link to post
Share on other sites
Mate - well done. That is a great effort. I've never even contemplated doing something like that!

 

TGL

The best way to increase your threshold is to work at your threshold for longer and longer periods of time. Its a very challenging way to train and takes training to even be able to train that way, but its a direct product of getting a good coach that knows what they are doing.

Share this post


Link to post
Share on other sites

Fishboy - this is a great tool. Thanks for posting.

 

Just calculated my CdA at ~0.285.

 

As a matter of interest how slippery did you get Tristian. I did not see it in the thread. More specifically what is a good CdA and what needs some work.

Share this post


Link to post
Share on other sites
Fishboy - this is a great tool. Thanks for posting.

 

Just calculated my CdA at ~0.285.

 

As a matter of interest how slippery did you get Tristian. I did not see it in the thread. More specifically what is a good CdA and what needs some work.

Hey cmg...

 

Thats about where I started before we started working on things.

Share this post


Link to post
Share on other sites
Hey cmg...

 

Thats about where I started before we started working on things.

 

 

We may need to talk...

Share this post


Link to post
Share on other sites

CdA's are a closely guarded sekrit...

 

0.275-0.285 typical triathlete

0.255-0.275 getting better

0.235-0.255 getting good, but you'll need a lot of tweaking to get here if you have shoulders, or are big

0.215-0.235 super good, but unlikely you'll get in this range without a skinsuit and pretzel like abilities, probably impractical for ironman or halfs.

< 0.215 slippery like a fish

< 0.200 aero god/goddess

0.195 Dave Zabriskie, winning world TT champ

0.185 Levi Leipheimer, lowest recorded CdA of TT cyclist at LSWT in San Diego.

Share this post


Link to post
Share on other sites
< 0.200 aero god/goddess

0.195 Dave Zabriskie, winning world TT champ

0.185 Levi Leipheimer, lowest recorded CdA of TT cyclist at LSWT in San Diego.

I have had one athlete lower and know another we've measured as lower as well.

Both have masters world titles/records.

Share this post


Link to post
Share on other sites

Parts of this thread is trigold. Especially the calculator thing. Can we get that at least posted over there, so we can find it when we need it?

Share this post


Link to post
Share on other sites
My IMWA CdA was 0.31. Looks like im ratsh!t,

Hey Ratdog

 

Blokes like you and me are always going to measure a bit higher on the CdA (due to our macho muscle man type physiques and our huge Arnie type shoulder width :lol: ).

 

Ok - even if we are not complete macho men, in fairness we are a bit bigger than your skinny whippet types on the bike so our CdAs will be a bit higher!

 

But 0.31 still seems a little high - you weren't wearing your pale blue beer mile safari suit on the bike were you?

 

Seriously, my recollection is that you sat on 220W for a 5hr bike split at Busso. Does this lead to a CdA calculation of 0.31 (and the last lap of Busso was pretty windy as well)?

 

TGL

Share this post


Link to post
Share on other sites
Its all those dodgy things you stick on your bike :lol:

Well, at the time I didn't think that Rattie having an entire Physics lab taped to his aero bars (so he could do some experiments during the race if he got the urge) would be a big problem?

 

Maybe it slowed him down more than he expected :lol:

Share this post


Link to post
Share on other sites
come on Tristan - lets see the before and after shots please.

Before...

 

IM%20Port%20Bike%202010%20crop.jpeg

 

After...

 

20x30-FYBA1114%20desk.jpeg

 

The after shot is close to where I am at the moment, but the second bottle at the front of the bars is not there any more and has been replaced with something else. I dont have a photo of this, but will post something after Port from the race photos there.

 

The wheels in the after shot are not accurate either (no discs allowed at Falls Creek). I run a HED Jet Disc, and a HED Stinger 9 front wheel. Aerobars are from our aero friends at HED as well, Corsairs... The best bars you can get bar none (get it, bar none...)

 

Anyway, there you are, 2.5km free (well expensive really) per hour.

 

Edit: One other thing, if I want to be as slippery as possible I will not be wearing that helmet, although the Rudy is very fast, the KASK is faster... The KASK is this...

 

Link

Edited by TristanP

Share this post


Link to post
Share on other sites
Before...

 

IM%20Port%20Bike%202010%20crop.jpeg

 

After...

 

20x30-FYBA1114%20desk.jpeg

 

Anyway, there you are, 2.5km free (well expensive really) per hour.

 

 

Link

Well glad that you cleared that up.

 

Looks like it is an open and shut case of the compression socks in the "before" shot slowing you down that 2.5kph........... :lol:

Edited by The Glycogen Lilo

Share this post


Link to post
Share on other sites

Hey Tristan, well done on the new aero numbers. Just a few questions. Is that an adamo saddle you are now using? Also if you were using a normal saddle how far forward of bottom bracket would the tip be. What power numbers did you get from Falls and what time did you ride there.

 

Cheers TiPhoon

Share this post


Link to post
Share on other sites

Thanks for sharing the photos Tristan!

 

Some quick Q's;

Elbows much closer together. How does this effect your breathing?

 

Elbows much lower due to forearm angle, side effect is head is much lower. How does this effect your visibility?

 

Seat angle must be close to 90% in the current shot, does this load up your quads or do your glutes still work ok at this angle?

 

Thanks again!

Share this post


Link to post
Share on other sites
Hey Tristan, well done on the new aero numbers. Just a few questions. Is that an adamo saddle you are now using? Also if you were using a normal saddle how far forward of bottom bracket would the tip be. What power numbers did you get from Falls and what time did you ride there.

 

Cheers TiPhoon

Not sharing power data at the moment, but will be happy to do so after Port. Falls is a little bit hard to use as a measure due to the hills as well as the road conditions. Also everyone would have been lower on the power figure due to altitude, but also marginally lower on drag for the same reason.

 

I rode a 2:19 there though... Also would have been faster with race wheels, but this would be marginal (although, those Mavics are about the slowest thing you could put on a bike)

 

I ride steep, like really steep... It is an Adamo, and I dont know what the seat angle figure would be with a normal saddle, but it would be well over 80 degrees

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×