Sub 20 10TT - Power needed?

bahzob

In a separate thread I heard that people are doing 19 minute 10 mile TTs at 300W.

This is great if true. I thought it would be closer to 400W.

Has anyone got an example of a 10 under or close to 20 minutes done at 300W? Any extra info like which course /race conditions/weight/height/bike setup would be helpful.

okgo

I don't know all of these guys, but a couple I do, and their weights are not extreme in either direction, set up is full TT get up, and the course is a fast one - this was just for ease as I could trawl other courses and find more examples :

http://www.strava.com/activities/184743444#4324828050
http://www.strava.com/activities/208875354#4924696585
http://www.strava.com/activities/184816758#4326706594
http://www.strava.com/activities/73200032#1443362414
http://www.strava.com/activities/184859551#4327849100 (less than 300w)
http://www.strava.com/activities/144410747#3301112259 (much less than 300w)

bahzob

okgo wrote:

I don't know all of these guys, but a couple I do, and their weights are not extreme in either direction, set up is full TT get up, and the course is a fast one - this was just for ease as I could trawl other courses and find more examples :

http://www.strava.com/activities/184743444#4324828050
http://www.strava.com/activities/208875354#4924696585
http://www.strava.com/activities/184816758#4326706594
http://www.strava.com/activities/73200032#1443362414
http://www.strava.com/activities/184859551#4327849100 (less than 300w)
http://www.strava.com/activities/144410747#3301112259 (much less than 300w)

Brilliant, thanks.

I am looking at the thread you mentioned http://www.timetriallingforum.co.uk/index.php?showtopic=70736&&page=2 atm as well.,

bahzob

It's obviously about the course as well as the power. V718 is obviously such a one though its not obvious as to why looking at its profile.

Given its so fast do you know how hard or otherwise it is to get a place on the start-sheet?

There's a course nearby me that is also quick P613, but it has nice profile where the start is downhill with no corresponding uphill on the finish.

Also if you know of any other similar please can you mention and I'll trawl Strava.

Couple of more questions if I may.
- How big, if any, is the difference between the power you put out in the most comfortable position possible vs aero. For me its around 10% less and feels a lot less comfortable but I have never spent any real time working on it. One goal this winter is to sort this out

- Is it possible to say very roughly (assuming non exceptional conditions) a time advantage a course like those above gives vs a more "normal" one for the same power? Is it of the order 2-3 minutes or just some 10s of seconds?

xavierdisley

P613 isn't used any more (for quite some time now ...) due to traffic lights at the turn.

No real point comparing riders unless you know their CdAs*. But for example at my current weight and aerodynamic drag I could do a ~19:59 with 285w on the V718, which for the same atmospheric conditions would give you ~21:25 on the H10/8, ~20:15 on the F11/10, ~21:45 on the P311, or ~22:25 on the K41/10, etc.

*say, for example, that you had a massive list of all the top riders' CdAs

Alex_Simmons/RST

bahzob wrote:

It's obviously about the course as well as the power. V718 is obviously such a one though its not obvious as to why looking at its profile.

Apart from the terrain which may or may not be favourable, in the UK in particular the courses are variable in terms of traffic flow and how much air flow assistance riders receive. Most other countries wouldn't dream of running TTs on many of the roads used there.

bahzob wrote:

How big, if any, is the difference between the power you put out in the most comfortable position possible vs aero. For me its around 10% less and feels a lot less comfortable but I have never spent any real time working on it. One goal this winter is to sort this out

It varies by individual. My best power output was on my TT bike (very motivated as it was a world cup), but my road bike power was pretty much the same. For others they experience power loss. Adaptation may take longer for some than others and high quality bike fitter can aid in that process on minimising power loss. The challenge is to work out what's fastest and that's an iterative process.

bahzob wrote:

- Is it possible to say very roughly (assuming non exceptional conditions) a time advantage a course like those above gives vs a more "normal" one for the same power? Is it of the order 2-3 minutes or just some 10s of seconds?

Pretty sure all you'd need do is look at the top 5-10 speeds attained on various courses to gain an idea of the differences.

Environmental conditions on the day can still make a large difference, let alone different courses. The difference between a cold day and a hot one on my local 25km course is about a minute. And that's with no wind. Wind screws it up even more. Doesn't need to be exceptionally wild or anything.

jimwalsh

F11/10 is quick

a fair few 300w efforts around the 20 mark.

they may all be 50 kg midgets though...
http://www.strava.com/segments/892764?filter=overall

okgo

Look at number 7, low 19 off only 320w!!

I should add my powermeter cut out for long periods of that TT ;-)

bahzob

jimwalsh wrote:

F11/10 is quick

a fair few 300w efforts around the 20 mark.

they may all be 50 kg midgets though...
http://www.strava.com/segments/892764?filter=overall

Gosh yes. strava profile makes it look like you are jumping of a cliff.

bahzob

Thanks for above. Very helpful. I'd already decided to make TT a focus this year which is why I got a copy of Adam Topham's book. This was where I got the 400W figure from, he mentions there are faster courses, I just didn't realise what a difference it would make.

bahzob

Alex_Simmons/RST wrote:

t's obviously about the course as well as the power. V718 is obviously such a one though its not obvious as to why looking at its profile.
Apart from the terrain which may or may not be favourable, in the UK in particular the courses are variable in terms of traffic flow and how much air flow assistance riders receive. Most other countries wouldn't dream of running TTs on many of the roads used there.

Yes couldn't agree more. One of our most popular courses has 2 roundabouts right at the end, made even more problematic by the fact that there is petrol station on the second and some cars need to make a full circuit of the roundabout to get to it. The difference between a good and terrible time can just be down to pure bad luck.

The other big thing about the UK is the quality of the road surface. This may explain differences not obvious in the profile.

I ride in France a lot and there are some beautiful pan flat courses over there that feel as if you are riding on a mirror that make you just want go faster and faster. Its a shame they are not that big into TTing, if they were I think it may be some very fast ones.

bernithebiker

bahzob wrote:

I ride in France a lot and there are some beautiful pan flat courses over there that feel as if you are riding on a mirror that make you just want go faster and faster. Its a shame they are not that big into TTing, if they were I think it may be some very fast ones.

Although there is a thriving race scene here in Brittany and the area produces lots of excellent riders, TT's are almost unheard of.

Grill

I will never hit 400w, but I will ride a sub 20 (not this season but within the next 2 after that). Reckon I only need to find an extra 30-40w (from peak last season which was 275w) and the right day and course. I dropped minutes off all my times last season even though my power was the same and I was riding heavier all due to lower CdA. If you have the power but not the position then it's going to be an uphill battle.

bernithebiker

As a light, low power rider, I've always thought I'm on a hiding to nothing doing TT's. It's hard to compete with the big guys knocking out big power on the flat.

There's also a big investment to be made in equipment and refining your position and everything aero related.

So I think I'll stick to my forte, which is hills!

okgo

bahzob wrote:

Thanks for above. Very helpful. I'd already decided to make TT a focus this year which is why I got a copy of Adam Topham's book. This was where I got the 400W figure from, he mentions there are faster courses, I just didn't realise what a difference it would make.

There are not many people doing 400w for ten mile time trials, there are loads of people doing sub 20 minute times. The top 80, yes eighty did a 19 at the national ten.

jimwalsh

bernithebiker wrote:

As a light, low power rider, I've always thought I'm on a hiding to nothing doing TT's. It's hard to compete with the big guys knocking out big power on the flat.

There's also a big investment to be made in equipment and refining your position and everything aero related.

So I think I'll stick to my forte, which is hills!

there is a lady in my club who must be 50kg dripping wet. in her late 40s she is doing short 21 minutes for 10... slipperiness seems to count for alot as well...

okgo

Aero is everything in time trials, clearly, otherwise there wouldn't be people doing 18 minute times off not much more than 300w. One rider I've linked to above, if he had the power I can produce (which is by far not the top top percentile of amateurs), would be competition record holder such is his slipperiness.

LegendLust

okgo wrote:

Aero is everything in time trials, clearly, otherwise there wouldn't be people doing 18 minute times off not much more than 300w. One rider I've linked to above, if he had the power I can produce (which is by far not the top top percentile of amateurs), would be competition record holder such is his slipperiness.

Exactly. Nigel Goskinski who I know well, is a tiny lad. He doesn't need the same power to push through the air as bigger lads

jibberjim

jimwalsh wrote:

there is a lady in my club who must be 50kg dripping wet. in her 50s she is doing short 21 minutes for 10... slipperiness seems to count for alot as well...

In the UK? Why doesn't she appear in the all time lists?

jimwalsh

dunno its on our club website. her 25 m time is on the vtta site but not her 10 mile time. (she is late 40s and would kill me for saying she is in her 50s)

http://www.hemelcycling.org.uk/club-cyc ... -champions

jibberjim

jimwalsh wrote:

dunno its on our club website. her 25 m time is on the vtta site but not her 10 mile time. (she is late 40s and would kill me for saying she is in her 50s)

http://www.hemelcycling.org.uk/club-cyc ... -champions

That's her only sub 22 and it's not short, and she's in her 40's not 50's, so a bit of exaggeration I'll forgive, you really don't need as many watts as people think which is your main point and that's right. You just need the right course on the right weather conditions (19:03 of Steve on the day she did the 21:28, and he's done a 18:19 on 320 odd watts...

Grill

F11 on a float day, one day! Good on her, strong tester.

jimwalsh

@jibberjim woah cowboy! I made a mistake rather than exaggerated. I don't make a point of asking ladies their age or PBs....

all I know is she kicks my arse up and down our club 10 every week and I could imagine that I might produce more watts then her (my fat arse and brick like aero qualities dont help)

cycleclinic

Also all these fast times are for riders with there position sorted and probably they have a fair bit of the best aero kit as well. If your are a aerodynamic then high power is not needed.

Alex_Simmons/RST

If roads are very smooth and flat then a windless power to aero drag ratio of ~1,650 W/m^2 is required.
For a 320W rider, you'll need a CdA under 0.2m^2.

But once you throw traffic induced wind assistance into the mix like a heavier trafficked DC course, the drop in power demand can be significant.

I have a client with speed 1km/h faster on a fixed gear road 25-mile TT in the UK than their world hour record on the track with a much faster surface. Traffic movement makes a big difference to air flow.

bahzob

bernithebiker wrote:

bahzob wrote:

I ride in France a lot and there are some beautiful pan flat courses over there that feel as if you are riding on a mirror that make you just want go faster and faster. Its a shame they are not that big into TTing, if they were I think it may be some very fast ones.

Although there is a thriving race scene here in Brittany and the area produces lots of excellent riders, TT's are almost unheard of.

That's a real shame. It did occur to me that, given the popularity of European sportives, a nice idea would be for a town in Brittany or similar to run a "Fete de Chrono". Set up some fast courses of various distances, close the roads to traffic (which seems to be no big deal in France) and invite all-comers spend a weekend trying to set PBs and celebrate with some local cuisine.

bahzob

Alex_Simmons/RST wrote:

If roads are very smooth and flat then a windless power to aero drag ratio of ~1,650 W/m^2 is required.
For a 320W rider, you'll need a CdA under 0.2m^2.

But once you throw traffic induced wind assistance into the mix like a heavier trafficked DC course, the drop in power demand can be significant.

I have a client with speed 1km/h faster on a fixed gear road 25-mile TT in the UK than their world hour record on the track with a much faster surface. Traffic movement makes a big difference to air flow.

Hm. Didn't realise this either, at least not to the extent you mention. Another piece of good news to go along with the reduced "actual" power you need compared to theoretical.

So, the more traffic the better (provided it doesn't cause braking)? And I can take solace that the occasional idiot that goes past hooting their horn in anger is actually helping me go faster?

This is also interesting for my aero testing. I do this on one of the courses we use but at a time when the road is much less busy than during our races. So it may not be fully accurate but likely to underestimate speed which is would seem to be preferable to being over.

bahzob

thecycleclinic wrote:

Also all these fast times are for riders with there position sorted and probably they have a fair bit of the best aero kit as well. If your are a aerodynamic then high power is not needed.

I have the kit but not the position. My power is 30-40W down compared to my road bike and in RPE terms the difference is even bigger. Sorting this out is number 1 priority this year so atm my TT bike is the one I use for turbo. Touch wood already making a bit of progress hence enthusiasm at finding out the extra power may be more useful in terms of time reduction than I had expected.

meanredspider

Yes - traffic makes quite a difference. So, forgiving the fact that it's a Strava segment, but if I climb the Kessock Bridge on the side WITH the traffic I'm so much faster than if I cross on the side AGAINST the traffic (for anybody that thinks I've lost my marbles and started riding on the wrong side of a busy dual carriageway, both are on segregated cycle paths separated from the traffic only by 3' of Armco (5' now)). I would think a steady stream of trucks (like the testers who ride on the A14 near Cambridge heading towards Felixstowe and Ipswich docks must see) must make quite a difference.

chrisw12

bahzob wrote:

Alex_Simmons/RST wrote:

If roads are very smooth and flat then a windless power to aero drag ratio of ~1,650 W/m^2 is required.
For a 320W rider, you'll need a CdA under 0.2m^2.

But once you throw traffic induced wind assistance into the mix like a heavier trafficked DC course, the drop in power demand can be significant.

I have a client with speed 1km/h faster on a fixed gear road 25-mile TT in the UK than their world hour record on the track with a much faster surface. Traffic movement makes a big difference to air flow.

Hm. Didn't realise this either, at least not to the extent you mention. Another piece of good news to go along with the reduced "actual" power you need compared to theoretical.

So, the more traffic the better (provided it doesn't cause braking)? And I can take solace that the occasional idiot that goes past hooting their horn in anger is actually helping me go faster?

This is also interesting for my aero testing. I do this on one of the courses we use but at a time when the road is much less busy than during our races. So it may not be fully accurate but likely to underestimate speed which is would seem to be preferable to being over.

Yeah I try to train when the roads are quiet but there's a definite strategy that needs to be practiced to use the traffic situation SAFELY.

I'm not advocating anything extreme like a white line position but as an example if I'm approaching a fast rb then I'll take a wider position earlier forcing the cars not to overtake, you can then use the car overtaking you on the exit of the rb.

There are other examples which if practiced can be safer than normal, but the trick, like all cycling is specific practice.

Alex_Simmons/RST

bahzob wrote:

Alex_Simmons/RST wrote:

If roads are very smooth and flat then a windless power to aero drag ratio of ~1,650 W/m^2 is required.
For a 320W rider, you'll need a CdA under 0.2m^2.

But once you throw traffic induced wind assistance into the mix like a heavier trafficked DC course, the drop in power demand can be significant.

I have a client with speed 1km/h faster on a fixed gear road 25-mile TT in the UK than their world hour record on the track with a much faster surface. Traffic movement makes a big difference to air flow.

Hm. Didn't realise this either, at least not to the extent you mention. Another piece of good news to go along with the reduced "actual" power you need compared to theoretical.

So, the more traffic the better (provided it doesn't cause braking)? And I can take solace that the occasional idiot that goes past hooting their horn in anger is actually helping me go faster?

This is also interesting for my aero testing. I do this on one of the courses we use but at a time when the road is much less busy than during our races. So it may not be fully accurate but likely to underestimate speed which is would seem to be preferable to being over.

Well the occasional car isn't a lot, I'm talking about courses with traffic volume, and also the way the road is set into the environment impacts how that air movement is sustained, and how the regular atmospheric wind interacts at rider height (atmospheric boundary layer considerations, lots of things going on with that). Part of why vehicles affects things so much is they are moving the air at the height on the rider.

Aero testing with traffic is pretty much a waste of time. Any test run performed with a vehicle passing in either direction will be biased to some degree and not comparable to other runs.

Once there is any air movement then the precision of field aero testing drops, meaning that one can probably determine large changes in aerodynamics OK (and which are usually pretty obvious anyway), but once you start refinements (aero optimisation really is an iterative process of working on a lot of small details) you need benign conditions.

Put in this way - on an indoor velodrome a rider riding on the opposite side of the track is sufficient to affect the data such that I would toss it. Unless of course I was testing the impact of having a rider on the opposite side of the track.