Average power drop while drafting

Quadsweep said:

For you guys with power taps etc.

When riding at a high speed ie: hammering in the saddle in a pace line, how much does your wattage drop when right behind the leader if he is of typical size?

You're talking about a line. From the front position all the way back to a 5 or 6 rider line there's a huge difference. And then as you move your way toward the front of the line, the power requirement increases.

I'm sure RapDaddyo or others would have a more precise answer to your question. But for me I don't know. It could go from 350 in front of the line down to near 200 at the end of the line, depending on the winds and the grade.

Quadsweep said:

For you guys with power taps etc.

When riding at a high speed ie: hammering in the saddle in a pace line, how much does your wattage drop when right behind the leader if he is of typical size?

I've used my PT during TTT's (2, 3, and 4-up), and bearing in mind that all riders in the teams had varying output, when I was in front I was doing 280-300w for 30-60 second periods, when I was drafting my power was anywhere between 150-220w. This is club level stuff so there's not much practice, except for 1 or 2 10's before the event. The other area I found a regular output occuring was getting back on a wheel after a go at the front, and this sometimes uses ~400w even though only for a few seconds. This can probably be smoothed out with more practice, but these are generally the figures I've been seeing.

Quadsweep said:

For you guys with power taps etc.

When riding at a high speed ie: hammering in the saddle in a pace line, how much does your wattage drop when right behind the leader if he is of typical size?

From Broker et al. (1999), data from team pusuit: 1st position 100%; 2nd, 70.1%, 3rd 64.1%, 4th 64.0%. The paper used to be available here: http://www.midweekclub.ca/articles/

asgelle said:

From Broker et al. (1999), data from team pusuit: 1st position 100%; 2nd, 70.1%, 3rd 64.1%, 4th 64.0%. The paper used to be available here: http://www.midweekclub.ca/articles/

you beat me to posting that!

ric_stern/RST said:

you beat me to posting that!

Do you know what happened to the link?

This will depend on speed and gradient- high speeds downhill will give more % advantage to the drafter, low speeds and + gradients will give less advantage.

AndROOb said:

I've used my PT during TTT's (2, 3, and 4-up), and bearing in mind that all riders in the teams had varying output, when I was in front I was doing 280-300w for 30-60 second periods, when I was drafting my power was anywhere between 150-220w. This is club level stuff so there's not much practice, except for 1 or 2 10's before the event. The other area I found a regular output occuring was getting back on a wheel after a go at the front, and this sometimes uses ~400w even though only for a few seconds. This can probably be smoothed out with more practice, but these are generally the figures I've been seeing.

asgelle said:

Do you know what happened to the link?

when i said you beat me to it, i meant the data, not the article link.

ric

asgelle said:

Do you know what happened to the link?

The URL is incorrect (.com instead of .ca) it should be

http://www.midweekclub.ca/articles/broker98.pdf

Here's a file from a fast group ride I did today. Just so happens we had a 6-man rotating paceline going, so should give you a pretty good sampling of what happens power-wise while rotating through. The terrain here was rolling and drops a few hundred feet from start to end going through a canyon. There was a headwind, so the pulls are a bit exaggerated, but really effective at illustrating the differences in power output, from 0 watts up to spikes of about 600 watts.

How come pace slows when you are putting power down? Did you lead on the risers a lot?

Alex Simmons said:

How come pace slows when you are putting power down? Did you lead on the risers a lot?

Power will increase like that on a rise for all riders, not just the leader. The more level playing field is what makes hills such a good opportunity to drop the wheel suckers.

asgelle said:

From Broker et al. (1999), data from team pusuit: 1st position 100%; 2nd, 70.1%, 3rd 64.1%, 4th 64.0%. The paper used to be available here: http://www.midweekclub.ca/articles/

And even before that, there was this:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=2318782&query_hl=6&itool=pubmed_docsum

acoggan said:

And even before that, there was this:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=2318782&query_hl=6&itool=pubmed_docsum

been a few years since i read that paper!

Fortunately, this group was working well together. There was only one guy who passed on one pull, and I could hear him sucking wind; he needed a break, and was still important to the success of the group if he could recover. He came back around and pulled on the next rotation.

I was pulling on some of the risers, but if there are some suspect riders in the group, I'd just as soon be at or near the front on the risers if the timing works out. If any riders don't respond well on the climb, I don't want to be stuck behind them and have to put in a harder effort just to get my position back in the group. You are still going to do some harder work when the road goes up regardless, and the draft benefit decreases with the lower speed as well.

Cheers,

Ethan

frenchyge said:

Power will increase like that on a rise for all riders, not just the leader. The more level playing field is what makes hills such a good opportunity to drop the wheel suckers.

Understand that but the file shows speed dropping coinciding with power increases, so if that's the case I can't readily see in the graph where the power was different drafting vs on the front? It's there I think - the section between 17.0 and 19.0 miles which looks like a flatter section, as compared with the latter half of the graph where the consistent power rises are much more obvious (and seem to be related to climbing, not necessarily pulling on the front - but could be both - hence my original question).

Don't get me wrong, I know the effect is real - I'm a wheel sucker from hell😄 I'm just trying to see if this example actually highlights the point well. Maybe some data smoothing would help.

I'll try to find a file or two myself. Team pursuit efforts might be worth a look....

Alex Simmons said:

Understand that but the file shows speed dropping coinciding with power increases, so if that's the case I can't readily see in the graph where the power was different drafting vs on the front?

Yeah, terrain tends to drown out any drafting effect around here, too. Certainly it's there, but it's hard to see without comparing every rider's files at the same time.

frenchyge said:

Yeah, terrain tends to drown out any drafting effect around here, too. Certainly it's there, but it's hard to see without comparing every rider's files at the same time.

Good point, gents. Probably not the best file for this as a flatter ride would eliminate the terrain variables. There is a pretty consistent pattern in relative terms throughout the ride file, however, and it might serve to as a good real world example for that reason. I'd be curious to see a flat TTT or something from the track as Alex suggested for comparison.

Cheers,

Ethan

wattsup? said:

Good point, gents. Probably not the best file for this as a flatter ride would eliminate the terrain variables. There is a pretty consistent pattern in relative terms throughout the ride file, however, and it might serve to as a good real world example for that reason. I'd be curious to see a flat TTT or something from the track as Alex suggested for comparison.

Cheers,

Ethan

I had a quick look at our Team Pursuit final file from Feb this year. Ignoring the first km where you have an acceleration phase and a turn pretty soon thereafter (I was rider #2, which I discovered was a pretty hard place to ride, not to mention the pacing mistake I made but that's another story), I note that in the final 2km my average power when on front was approx 400W vs 260-280W in the paceline. Guess what, that is 65-70% of power when on the front. That was at 53km/h.

Attached is the CP power chart.

The horizontal power lines are set at 280W and 400W and the speed line is 53km/h.

I applied 10 sec smoothing to make it easier to see the effect - the raw chart is pretty ugly:eek:

I didn't bother with the qualifier file - we passed the other team twice! And being on the front both times really stuffed up our qualifying time (not to mention my legs).

And if you think you need to ride close to get that level of drafting, see attached photo - that's me in third wheel - so you'll get some idea. You absolutely have to have confidence in everyone on the team. See how rider #1 has drifted high - that is inefficient riding for everyone.

Alex Simmons said:

And if you think you need to ride close to get that level of drafting, see attached photo - that's me in third wheel - so you'll get some idea. You absolutely have to have confidence in everyone on the team. See how rider #1 has drifted high - that is inefficient riding for everyone.

Cool photo. It's also awesome to see a disk front wheel with deep-V rear to make room for the PM -- sweet! 🙂