Protocol for slipstreaming another cyclist?

Question

I have a nice 12 km commute where lots of different bicyclers travel. The entire stretch is only for pedestrians&bicycles, no cars to worry about.

I ride a regular old 5-speed bike (not a racing bicycle or mountain bike), but I'm a very fast biker compared to the general bike traffic I see (average 25-30 km/h). I'm only overtaken by people on electrobikes, and by fanatics (all the right gear, but no bell because it weighs 12 grams?).

It might be interesting to ride closely behind someone whose speed matches mine, but what's the protocol for doing this, apart from road safety concerns? Should I address people first, ask their permission? Or do I just approach from behind and stay close to them, without specifically indicating that I'm there?

At my speed, I won't be stalking a granny -- it would probably only ever be a lone hobby race cyclist here or there. Note that I am steering clear of team bicyclists; they probably have their own patterns that I don't want to interfere with.

I've noted someone following me a few times (without any indication) but it doesn't bother me because people who can keep up with me usually overtake me after a while anyway, so at best I've given them a moment's pause. As long as they don't crash me, they're welcome.

Add-on question:
It's clearly more polite to take turns leading, but does it cost you more energy when someone is following you, compared to cycling alone?

Answer 1

I've found it courteous to come up beside the person and ask permission. I usually say "how far you going?" or "mind if I join you?". The real key is to take turns drafting. If the person says yes, I usually take the first pull in front just to show them I'm not a wheel sucker.

As an avid cyclist, I've found very few things more annoying than riding for a good chunk of time, only to look back and find someone just sitting on your wheel with no announcement or indication that they are there.

Answer 2

It might be interesting to ride closely behind someone whose speed matches mine, but what's the protocol for doing this, apart from road safety concerns?

In my experience, if you can keep up then you can draft someone. There's no asking involved, but it is appreciated if you switch up to lead for a little while.

At the speeds you're talking, with the exception of those on electric bikes, most of those cyclists will be involved in some form of cycling (track or road, mountain less so) so they aren't as bothered as others might be. Some will get "cat 6" on you, and try to drop you if they notice.

The real issue is that the person leading needs to communicate their movement, like avoiding obstacles (glass, people, holes, etc). Drafting really close (wheels are close -- within 1 inch/2.5 cm, or far worse - overlapping) gets more dangerous at the higher speeds because as the person drafting, you don't have the time to react to quick braking/etc. As the person drafting, you should not be relying on the leader/person ahead to point stuff out - you should be looking ahead and around to anticipate as much as you can for yourself.

does it cost you more energy when someone is following you, compared to cycling alone?

No. The leader is working harder, breaking the wind for those behind them. Having people behind you doesn't change that.

Answer 3

There is more to consider than just whether you're slowing down the lead rider. I find someone drafting on me annoying, because it forces me to consider them and their actions. Particularly when I'm on my commute home I find it selfish that they're imposing that on me.

For example when I approach a slower bike to overtake, I do a head check to make sure the coast is clear behind me. However, then I see the drafting bike and have to assess whether they're attempting to overtake me or just sitting on my wheel. If I knew them and trusted them I'd probably be safe in assuming they're going to stay on the wheel, but for a random person I can't trust that they won't be trying to overtake me.

I've also had someone ride into the back of me because I've had to slow down due to foot traffic on the bike track. When it's safe I use hand signals and call out changes, but it's not a responsibility I want or have asked for.

There are other examples, including turning corners and none of them are that serious, but put together they add up to a bunch of small inconveniences that aren't welcome. In summary, on a commute I don't think it's okay to draft at all.

This all changes on a weekend blast, as I suspect more riders are willing to get in a line on a looooong stretch into a headwind :)

Answer 4

When people do this with me, I indicate after half a mile or so that I'll let them take the lead for a while, and then without much further discussion we tend to rotate like that until one turns off - and generally we'll wave.

Never really formalised this though.

Answer 5

I would think that the safest approach would be join on behind for enough time to adequately work out the person's speed (30-60 seconds) then to pass them slowly and deliberately, slowly, move back in, offering your wheel in return (i.e. take your time, don't massively accelerate and then brake - if you've a computer, you know the speed they were at, match it when you're in front as quickly as possible). They would probably not have noticed you, but by deliberately swapping places, you're explicitly offering to share the work - and they can then show their answer:

• slackening their pace and letting you go
• sticking to you and then passing you
• dropping the hammer and leaving you for dust (strictly an attempt to drop a perceived Fred)

I think it's the safety angle that would most concern me; riding in a paceline, swapping the lead duties, but mostly the riding close to the lead rider's rear wheel is tricky and not everyone can do safely at speed. An organised line will have signals and protocols borne from shared experience and these are important in avoiding obstacles and reacting to events - you'll be missing these, and you'll be in a potentially more target rich (i.e. many slower peers) environment.

As to the question of expense, there are some references, e.g. http://www.exploratorium.edu/cycling/aerodynamics2.html, http://www.bicyclesource.com/slipstreaming, suggesting that the lead rider could actively benefit from being drafted due to the effects of the air closing back around them.

Answer 6

Racers might call it "slipstreaming", but normal road users call it "tailgating". Other than in controlled conditions (like a race, or a cycling club ride), you shouldn't attempt it. It's dangerous, and no less rude than if you do it in a car.

If I catch you doing this behind me, I'll slow down until you back off, just like with any other tailgating vehicle. And if you "invite" me to tailgate you by overtaking and cutting me up, I'll probably respond with a rude gesture.