Sharing the work.

mech_daddy

Can somone please explain to me how this works. I know first hand that it does as it is a technique that me and my cycling buddies use often but what is the theory behind it. Seems to me that everyone has to do the same work (in terms of energy output) so how is it easier to follow???

andrewjoseph

Are you talking about draughting, i.e. riding close behind another rider?

If so, the riders behind the lead person expend less energy due to not being exposed to the air in the same way. They ride in the 'wind shadow' of the lead rider so don't have to push the air out of the way in the same manner.

When you all take turn to lead then everyone should be expending the same energy, but are able to travel at a slightly higher average speed than a rider would do if alone.

At least, that is what i believe happens.

Bronzie

Because you require approximately 20-30% less power to ride in someone's slipstream - this means when you get to the front you can put in a harder effort than you could if you were riding at a constant speed on your own, and when you've done your turn you swing to the back and have time to recover before you hit the front again. You are effectively riding short intervals with recovery time between each effort.

mech_daddy

Wow i didn't know aerodynamics would have such an effect.

felgen

I remember reading this on an Aussie site http://www.bikeon.com.au/ride_mag5.html (am going to Aus in the new year and definitely taking the bike!) and they quoted this table which I suppose may answer your question. I dont know who provided the figures though.

The effect of drafting

Wheel gap in cm            decrease in resistance

150                                      44%

300                                      42%
 
600                                      38%

900                                      34%

Alex_Simmons/RST

mech_daddy wrote:

Wow i didn't know aerodynamics would have such an effect.

It has a huge effect. This is why top road sprinters only stick their nose out into the wind at the very last moment. The higher the relative air speed, the more important it is.

When riding on flatter terrain, the majority of our power goes into overcoming air resistance.

Drafting can reduce the oxygen cost by 25%-40% and is most notable of course on flatter terrain. One you hit the hills, then overcoming gravity is the biggest factor.

Martin et al and Jeukendrup have reported that in one TdF stage, a rider with excellent drafting skills was able to complete a six-hour road stage with an average speed of 40km/h with an average power of just 98 watts! Doing so by riding solo into the wind (for that rider) would have required an average of ~ 275 watts.

In Team Pursuits, the riders folowing the leading rider have power outputs around 65-70% of the lead rider.

It's one of the unique things about mass start cycle racing, that a stronger rider may not always be able to "drop" a weaker rider, simply because of the large difference in power required to ride in front versus behind. It's also why large peleton working together has this great ability to catch a small or lone breakaway rider.

mech_daddy

Thats amazin, so does the effects of drafting increase with more people in a line or is one enough?

Bronzie

The more the merrier 8) - once you get beyond 3-4 riders in front of you, it makes little difference, but then when you also have people on both sides as well...........you hardly have to touch the pedals at all

joeyhalloran

I believe that sitting 3rd or 4th in a line or further back makes no difference, although there is a difference between 2nd and 3rd. Of course it also makes a difference to the recovery time you get while drafting, the more people the longer the break while others take the lead.

GeorgeShaw

Bronzie wrote:

The more the merrier 8) - once you get beyond 3-4 riders in front of you, it makes little difference, but then when you also have people on both sides as well...........you hardly have to touch the pedals at all

As a relative newbie, and pretty crap rider, I can only agree. I did the Vatternrundan in Sweden in the summer, when groups of up to 100 form for long periods. I did 300km in a shade over 10 hours i.e. about 30kph. I've only beaten that average speed once solo for any distance over 30km.

As Bronzie says, at times I was feathering my brakes more often than pedalling, at between 35 and 40kph.

bill57

felgen wrote:

I remember reading this on an Aussie site http://www.bikeon.com.au/ride_mag5.html (am going to Aus in the new year and definitely taking the bike!) and they quoted this table which I suppose may answer your question. I dont know who provided the figures though.

The effect of drafting

Wheel gap in cm            decrease in resistance

150                                      44%

300                                      42%
 
600                                      38%

900                                      34%

Are you sure these figures aren't out by a factor of ten? 900cm is about thirty feet, I suspect you'll get bu**er all drafting effect at that distance! In the few duathlons I've done, I think the minimum gap you must maintain between bikes is seven metres. According to these figures you'd still be getting about 36% drafting effect.

ColinJ

bill57 wrote:

Are you sure these figures aren't out by a factor of ten? 900cm is about thirty feet, I suspect you'll get bu**er all drafting effect at that distance! In the few duathlons I've done, I think the minimum gap you must maintain between bikes is seven metres. According to these figures you'd still be getting about 36% drafting effect.

You're obviously right about that - it should be in mm or divide the cm distances by 10.

There is some good advice on group riding if you follow that link.

oldwelshman

mech_daddy wrote:

Wow i didn't know aerodynamics would have such an effect.

You should draft behind one of those new fast tractors that were out recently harvesting the crops I managed 37mph for a few miles behind one coupe of weeks ago on nice clear stretch.
Not advisable if you are on windy narrow roads tho Better still and much safer as long as you can ride a fixed fast, go to a track and do a derny session
Think they are still on at Newport but not sure if the track league starts next week so it may finish this week!

guv001

I've seen the Derny whizzing round Maindy track on a Thursday towing riders...

oldwelshman

I may be wrong but I haven't seen a derny on the Thursdays, I have been on a Thhursdy as several times. Seen it for the sprinters after the vets sessions on Fridays and also on Tuesdays.
Not managed to get there for training when its there yet

guv001

I'm talking about Maindy not Newport OWM

oldwelshman

guv001 wrote:

I'm talking about Maindy not Newport OWM

I should have read your last post more closely
I think they are now doing road bike racing for a few thursdays on Maindy Track?

felgen

yeah sorry. Those measurements are definintely in mm not cm. And, yes it was quite a good read regarding group riding in general

derekwatts

Raises an interesting question about 'draughting ettiquete'!

If you are out on a solo ride, doing your own thing and trying to avoid cheating in a tow, how do you feel about someone sucking on your wheel without so much of a kindly word or a polite request? I suppose this happens more on a shortish training loop with people whizzing around trying to beat PB's. Happens a lot on my local loop. I did it myself a bit to begin with but then realised I wasn't getting good comparitive data from each ride, and deceiving myself some days that I had rode a great session, so now I avoid sucking wheels.

Also, I notice nobody talks about the benefit to the rider in front as well if you have a long line of riders draughting. May be small, but you do get some benefit with other people draughting you, because they alter the drag profile coming off your bike and also reduce resistance... Never seen any figures for that though.

Alex_Simmons/RST

derekwatts wrote:

Raises an interesting question about 'draughting ettiquete'!

If you are out on a solo ride, doing your own thing and trying to avoid cheating in a tow, how do you feel about someone sucking on your wheel without so much of a kindly word or a polite request? I suppose this happens more on a shortish training loop with people whizzing around trying to beat PB's. Happens a lot on my local loop. I did it myself a bit to begin with but then realised I wasn't getting good comparitive data from each ride, and deceiving myself some days that I had rode a great session, so now I avoid sucking wheels.

Also, I notice nobody talks about the benefit to the rider in front as well if you have a long line of riders draughting. May be small, but you do get some benefit with other people draughting you, because they alter the drag profile coming off your bike and also reduce resistance... Never seen any figures for that though.

I think we are talking about drafting and not draughting. Unless you are planning on doing some engineering design work while riding your bike.

If a rider wants to ride behind me, I think it is polite for them to ask if me I'm OK with that. Most of the time I don't mind but just occasionally I prefer them not to as I want to concentrate on what I am doing and not have to take on the responsibility of picking wider lines around debris, pointing holes etc.

If they don't ask, then I pay them no attention and get on with what I'm doing. Sometimes it acts as a good incentive to keep the pressure on the pedals. So, as with most riding, use the conditions and circumstances to your advantage, whether that be for a training or racing benefit.

As for riders behind reducing your aero drag, I'm not aware of data but it would be very very small if at all and is probably an old coach's trick to get a rider to hang on in team time trials

derekwatts

Alex_Simmons/RST wrote:

[I think we are talking about drafting and not draughting. Unless you are planning on doing some engineering design work while riding your bike. As for riders behind reducing your aero drag, I'm not aware of data but it would be very very small if at all and is probably an old coach's trick to get a rider to hang on in team time trials

Bu**er! Err, no I was indeed talking about draughting. Do you think it's ok for someone to ride along in your wake with a sheet of A4 taped across their aero bars, whilst taking precise measurements of their seat tube / top tube, without paying due attention to the rider in front... Do you think it's dangerous? But Anyway, regards the aero effect of having another rider behind you, I have seen no data relating to cycling (which doesn't surprise me), but its quite well documented in other sports with engines... If you look on high speed ovals in the USA, a pair of NASCAR race cars 'drafting' will lap quicker, on circuits where it's just foot flat to the floor all the way around. A line of them will lap quicker still, if you are looking at pure aero effects. Five riders in line will effectively act as one long aerodynamic body, with a totally different form factor than a single rider, so it should make a small difference, though perhaps not as graphically illustrated as with a race car. After all, it's the turbulence, vortices, eddy currents etc that are shed behind you that creates the 'work' in overcoming aerodynalic resistance...

guv001

So how do a team eg CSC drop everyone by riding on the front surely they as a team are expending more energy than the other teams behind. Does this just come down to fitter stronger riders or is there another tactic I'm missing?

Also how is it harder pulling another rider uphill (except for the draughting effect which must be reduced at such low speeds) is this purely pyscological?

Mettan

derekwatts wrote:

Raises an interesting question about 'draughting ettiquete'!

If you are out on a solo ride, doing your own thing and trying to avoid cheating in a tow, how do you feel about someone sucking on your wheel without so much of a kindly word or a polite request? I suppose this happens more on a shortish training loop with people whizzing around trying to beat PB's. Happens a lot on my local loop. I did it myself a bit to begin with but then realised I wasn't getting good comparitive data from each ride, and deceiving myself some days that I had rode a great session, so now I avoid sucking wheels.

Also, I notice nobody talks about the benefit to the rider in front as well if you have a long line of riders draughting. May be small, but you do get some benefit with other people draughting you, because they alter the drag profile coming off your bike and also reduce resistance... Never seen any figures for that though.

Yes, apparently drafting does marginally benefit the rider in front - something to do with "filling in their eddy" - (only briefly read that though, not seen any data). Regards drafting on solo training rides - don't see a huge problem with it myself - typically you'll only be with someone (or them with you) for one or two miles at most (before someone turns off) - also, if you've already got 30-40 hilly miles in your legs (for example) and you close up behind another roadie doing 23 mph on the flat (on a decent route), it's not as if your going to move up to 25/26mph and sustain that for 3 or 4 miles (some could obviously - but on a "moderate" Sunday...), rather, you might just tuck in and have a rest for a mile or two - and there's the cameradary (spelling?) angle aswell. In the grand scheme of things, it's not a huge issue (all imho). Obviously there's nothing stoping somebody saying hello before tucking in etc,etc, and if your on fresher legs, nipping past and droping someone.

Patrick1.0

guv001 wrote:

So how do a team eg CSC drop everyone by riding on the front surely they as a team are expending more energy than the other teams behind. Does this just come down to fitter stronger riders or is there another tactic I'm missing?

Also how is it harder pulling another rider uphill (except for the draughting effect which must be reduced at such low speeds) is this purely pyscological?

I think the idea is when all the riders are a bit sore and tired, a team as powerful as csc moving to the front and raising the pace, is going to cause problems. If you're a GC contender and you're having a bad day, the last thing you want to see is csc rolling to the front and sending the pace up. It of course means that they expend a lot of energy, too, that's the price they have to pay for attempting to put other riders in difficulty.


It's not harder to pull somebody uphill. However, there is a small advantage to be had, even on a climb, from drafting in behind somebody. That's why you see guys sit there and hold a wheel all the way to the top before nipping out and darting past the rider they've followed all the way up in the last few hundred metres, sometimes only a handful of metres from the line. There's also the tactical advantage of getting the jump on the person in front.

Alex_Simmons/RST

guv001 wrote:

So how do a team eg CSC drop everyone by riding on the front surely they as a team are expending more energy than the other teams behind. Does this just come down to fitter stronger riders or is there another tactic I'm missing?

Are you talking flat land or hills?

On hills it's mostly about power to weight ratio, so if you have more good climbers on your squad, then chances are you'll have the numbers to keep the pressure on. While reduced, there is still a drafting advantage to following a wheel up hill. So what happens often in these type of teams is the team leader's helpers will sacrifice themselves without necessarily the expectation themselves of being able to go the full distance at that pace.

But it is more often about tactics and it depends on the type of rider. Some cope better with accelerations and variable paced efforts (e.g. Pantani), others prefer a more consistent effort level (e.g. Leipheimer, Evans), so often the attacks are made by a leader's team mates, knowing that the opposition rider who is outnumbered must respond (since the team mates are still a threat in their own right), even though it is not his preferred means of climbing.

On flat lands, the team on the front shares the work and drives it hard. Especially effective in strong cross winds at breaking up the peleton since not everyone can fit into the echelon and gain the benefit of a draft, meaning that the riders behind effectively are forced to put in as much effort as the riders driving the pace. Any weakness on that day, and you are in big trouble.

Really good teams know exactly how wide to make the echelon, so that only their team mates get the most benefit from the draft. It is brutal at times and requires one to get good at riding in the gutter. Then the punctures come and so on.

guv001 wrote:

Also how is it harder pulling another rider uphill (except for the draughting effect which must be reduced at such low speeds) is this purely pyscological?

It isn't. It's more to do with tactics.

The rider behind is still getting some assistance, so by towing them you are using more energy and setting them up to overtake you for the win. That determines your tactics. In some cases, the lead rider will do that because they are more interested in establishing a time gap over dropped riders and will sacrifice a win in the process as it is faster overall to ride at a constant effort than play tactical games on the way up.

deal

derekwatts wrote:

Raises an interesting question about 'draughting ettiquete'!

If you are out on a solo ride, doing your own thing and trying to avoid cheating in a tow, how do you feel about someone sucking on your wheel without so much of a kindly word or a polite request?

I would tell them politely to bugger off, the reason being is they will likely tell you the same thing when you ask them to pay for any damage and possibly loss of earnings in the event of a crash.

If part of a group ride and I get brought down by someone else i would not expect nor ask for any damage to be payed for, by being part of the group ride i have accepted the Inherent risks. If they ride along side, say hello and ask for a tow fair enough provided they dont look like they just removed there stabilizers, and like the previous case I have accepted the risk.