What percentage of FTP for a 20k TT?

I’m doing the local TT tonight. It’ll be my first time racing with power and my first time racing since doing some triathlon 4 or 5 years ago, so I’ve got nothing to guage my effort off. I’ve heard on the podcast a bunch of recommendations for longer things (Ironman etc) being 65-75% of FTP but what about shorter things?

I reckon I’m going to be out there for something around the 40 minutes, so what %age of FTP should I aim for. As I read it FTP is your hour power and as I’m doing 2/3rds of an hour I should be able to give it some more, what’s the concensus on this, are we talking 5%, 10%?

I would start 95% for about 15 min and then go up to threshold and then turn on the boosters for the last 5-10 min.

It also depends quite a bit on the course. Are there hilly sections that you need to save some effort for?

20k isn’t that far if the course is flattish. Break it down into quarters. Something like:

First 5k - a bit easier than you think you should go. Say 90% FTP

Next 5k - push it now somewhere around 100% FTP

Next 5k - Just over ftp. Say 103% to 105%

Last 5k - Push it as fast as possible and in the last 2k absolutely bury yourself.

Alter the above based on whether there are some hills. More power up the hills. Ease off slightly and take a slight rest on any down hills.

Don’t shoot for a specific FTP mark IMO

20km is somewhere in the high 20 to low 30 minute range.

Start a little low for the first 5 minutes, and then notch it up from there until you feel like you are surfing the edge. As others have said, burn the juices in the last 5k.

You’ll learn more about yourself and your abilities this way.

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This totally depends on the course whether flat or hilly etc.

True. Usually the ones that are longer time wise are classified as hill climb TTs though.

Here’s the course:

It’s “rolling” at worst. Pretty flat really. There’s going to be a slight south/south-westerly breeze which may or may not help on the flat roll in to the main up-hill heading north on the A61.

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So the key stretch is the one going up the long drag that heads north. This is where you can save or lose the most time. So stay focussed and realise that once you get to the top point of the course it is mainly down hill after that.

So more effort going up that long drag heading north. Get round the bend and heading back south-west you can hammer it once you have recovered after the climb up.

But also bear in mind that the prevailing wind may make the downhill not as downhill as you would have liked. Stay as aero as possible whilst maintining power when hitting headwinds…

Good luck.

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If you want to get super nerdy, plug the course into bestbikesplit it will tell you where to go hard and where to ease off


Last year I ride to.power on shorter TTs (10 miles) and on a couple I was disappointed as I finished feeling like I could’ve done more.

This season I’ve ridden to feel for 10mTTs and have PB for the distance. The key is not going crazy for the first couple of minutes, then just riding right at the edge of what you think you might not be able to sustain. Last mile or so is desperate but you will surprise yourself what you can do.


If you’re pretty experienced with sustained power efforts you shouldn’t have too much trouble holding 100% FTP for the duration of the TT in my opinion. Coming up any little climbs you can put a little more power down (but keep a good handle on it - 120-130% ftp) and use the back of the rollers to recover a little bit then settle back into threshold. If your FTP is tested correctly you should be feeling like its way too easy at the start, then arrive in the last 5km with just a tiny bit more left in the tank to push up above threshold to the line.


… and here you have it.

That was bags of fun.


Is your 400w FTP correct on your device? 0.60IF seems low for a short TT?

Nice work! Looks like you let up when you got to the top of the climb when you should have kept hammering as you crested and things flattened and recovered on the downhill portion. There is a HR peak there too so maybe you went a bit too far into the red?

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Ah, no…

First time out with a real power meter. Didn’t know there was an FTP set on the head unit. The IF on TR was 1.1 which seems right because I sacked my FTP test off early last night but I was pretty close to failing.

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What did you learn from the ride?

What would you do differently to improve your time?

don’t start too hard, whatever you do…and the power meter can let you do that, if you aren’t having a stellar day. Sometimes you plan to do X watts, but the body allows X - 10 Watts.

Get out the gate and get the bike to speed, then rip it by feel. Get halfway there and not dying…really ramp it up towards the end.

Afterwards, look at the power and use the data to continue to get faster and learn what #s you put out.

Let us know how it goes! I’d love if you tag me in the reply

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I managed to stay aero for about 90% of the ride which I was surprised at. I was also surprised by how little speed 240/250w gets you out on the open road.

I think my biggest area of improvement is just plain old ability. I’m reasonably “fit” but still not cycling fit after only a few months back on the bike.

It was an interesting and exciting experience which I’m keen to repeat, hopefully this Thursday.


Keep at it.

Obviously training and power improvement is vital but so too is aero improvement.

The more you do it, the more data/knowledge you will get to help you prioritise things for faster times.

Good luck.

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