Drafting Lorry/Buses

[Deleted User]

Hi,

Been comutting a while and now and again I get a nice tow behind a bus or van at around 30mph. Is this considered bad practice or frowned upon? Dose anyone else do it?

I am respectful of the highway code/traffic lights ect.

willy b

As long as it is safe, fair play. I certainly will happily do it although not too closet due to stopping distances etc...

rolf_f

Are you respectful of the buses stopping distance? I'd hate to be drafting a bus or lorry at 30mph if it decided to do an emergency stop........

Kieran_Burns

http://youtu.be/ZH5b2Ol_qYM?hd=1

iPete

I wouldn't recommend it but certainly do it you can certainly mitigate much of the risk by knowing the route [bus stops and so on], riding to the side to see whats ahead [traffic etc] and leaving a reasonable distance.

daviesee

Your gamble, fair game.
Back off as far as you can while keeping within the draught (keep some braking distance).
Hands on brakes.
Listen for throttle changes.
Stay to the left or right for an out (whichever is safest, never central).
Morally and legally no different to tailgating.

If it goes wrong you are at fault and you are the one that will get hurt. Your choice.

(Somebody may pick up on a legal basis. Is there a legal braking distance for cyclists? I don't think so.)

iPete

Motorpacing, looks like fun training.. http://www.youtube.com/watch?v=hnk4_9GnAU0

Canny Jock

Watch out (if you can) for potholes - nothing worse than seeing the bus slow and then suddenly have one in your way.

daviesee

Canny Jock wrote:

Watch out (if you can) for potholes - nothing worse than seeing the bus slow and then suddenly have one in your way.

Oh! So true. Know your route.
Clubmate was doing well draughting WVM who cut him up until he hit a speed bump. Nasty!

The Rookie

daviesee wrote:

Your gamble, fair game.
Is there a legal braking distance for cyclists? I don't think so.

There isn't for any road user, in fact I have no idea at all what your on about!

Simon

daviesee

The Beginner wrote:

daviesee wrote:

Your gamble, fair game.
Is there a legal braking distance for cyclists? I don't think so.

There isn't for any road user, in fact I have no idea at all what your on about!

Simon

Google shows that you are quite correct. There is no specific offence for being too close.
I suppose it woould fall into dangerous driving if in a car. Can you get done for dangerous cycling?
Better?
Google says no.

Topaxci

I've done it on occassion when I have a safe enough out on a wide piece of road. Would always stick to the outside edge though as buses tend to swing to the kerb when they stop. Usually leave them behind after the first bus stop.

Around here we're more likely to draft tractors, they shift alot of air and tend stick to 25-30 mph.
Though not without thier own risks, one of my friends took a draft on a tractor towing slurry last summer for several miles. We had to keep him to the back of the group for the rest of the day, he stank

gbsahne001

I do it on my route from time to time and provided you're listening for engine noise have never had a problem.

The biggest issue I've found concerns other road users, whilst you're glued to the back of the bus / lorry drivers at oncoming junctions cannot see you. The tendency I've found is for them to time their move out of the junction to coincide with the bus going past, if you're not ready for this it could be messy.

iPete

Yup, have to be careful for cars or people jumping behind the bus/lorry as it passes thinking its clear, need to know your road and pick your side to be seen.

Canny Jock wrote:

Watch out (if you can) for potholes - nothing worse than seeing the bus slow and then suddenly have one in your way.

Been there, done that, bought a new wheel :oops:

CiB

I do it occasionally on the Bicester bypass along by the gliding club. It's billiard smooth, no junctions for a mile from one r/bout to the next and if a slow-accelerating vehicle like a Land Rover + horsebox or a full cement wagon hovers into view it's fair game from my PoV. PB = 46mph until I gave in, last time.

Pay attention to engine note and keep the brakes covered and you should be ok. If it all goes pear-shaped you have a bike doing 30+mph running into the back of a vehicle braking from a faster speed. The closing / impact speed won't be that great (hopefully).

rick_chasey

CiB wrote:

I do it occasionally on the Bicester bypass along by the gliding club. It's billiard smooth, no junctions for a mile from one r/bout to the next and if a slow-accelerating vehicle like a Land Rover + horsebox or a full cement wagon hovers into view it's fair game from my PoV. PB = 46mph until I gave in, last time.

Pay attention to engine note and keep the brakes covered and you should be ok. If it all goes pear-shaped you have a bike doing 30+mph running into the back of a vehicle braking from a faster speed. The closing / impact speed won't be that great (hopefully).

Indeed.

Also, I'd be surprised if you bike can't stop in less distance than a car/lorry for the same speed.

bails87

I do it. I know it's probably a bit naughty, but I keep as safe a distance as possible, easily done with a double decker bus or really tall HGV. Drafting something like a normal van means getting pretty close to get the benefit, which makes it riskier.

EKE_38BPM

I'm not sure if a bike has a shorter braking distance than a motor vehicle and I can't be bothered to do any research, but I think a large part of the problem is the reaction time/thinking distance. If what you are slipstreaming slams on the anchors to perform an emergency stop, even if you are watching the brake lights and listening for engine note changes, by the time you notice and react, you could well be eating large chunks of metal.

I enjoy the idea of slipstreaming more than the reality and rarely do it. I think I'm getting old.

notsoblue

Canny Jock wrote:

Watch out (if you can) for potholes - nothing worse than seeing the bus slow and then suddenly have one in your way.

+1 When you're that close you can't see potholes to avoid them in time. I once hit a nasty one while drafting a lorry at 34mph and had a bit of a wobble. Its quite a risk. Fun though :oops:

rjsterry

Soem data on stopping distances here http://www.ukspeedtraps.co.uk/stopping.htm.
This site - http://www.exploratorium.edu/cycling/brakes2.html - reckons a bike can stop in about 10m from 30mph. Seems a bit optimistic to me, but much less than a truck.

Obviously, things are different on wet roads.

rick_chasey

rjsterry wrote:

Soem data on stopping distances here http://www.ukspeedtraps.co.uk/stopping.htm.
Will try and find comparable data for bikes.

Bikes will vary quite a bit, depending on how much the rider weighs, since the bike is such a small proportion of the overall weight.

DonDaddyD

Saw someone do it along Clapham and happyily face planted the van. Another guy did it behind a car, same thing.

Your shout, but in London where vehicles are known to stop suddenly I'd rather not.

veronese68

I rarely do it, but then I rarely get the chance. I sit right out to the off side so I can slide alongside if necessary. I do worry about my brakes, canti's.

bigmat

rjsterry wrote:

Soem data on stopping distances here http://www.ukspeedtraps.co.uk/stopping.htm.
This site - http://www.exploratorium.edu/cycling/brakes2.html - reckons a bike can stop in about 10m from 30mph. Seems a bit optimistic to me, but much less than a truck.

Obviously, things are different on wet roads.

Is that stopping distance with the aid of the now stationary lorry you were just drafting?! I might get in the draft of a motor vehicle, but usually will be on its right wheel so I can pop my head out to see what is ahead and have an escape route if they slam on the brakes. Tend not to get too close either .

sketchley

As rule I don't. Although it is tempting. I would never ever do it unless I can see the road ahead of the vehicle and I had an escape path. For example a few weeks a ago on the highway, I drafted a truck at around 30mph by sitting on the far outside where I could see through (it was container on flat bed type things) and round the truck to see obstructions it might face, plus the truck had not long pulled away first from set of rights so I knew not much would be in front, plus if it did break then I could simply of gone down right hand side. When the gap to the right was blocked I backed off to give more time.

mudcow007

i do when i get the chance, there aint nothing like the warm fuzzy feeling of been dragged along in the wake of a bus/ artic

i always hover around the near side edge though so A. the driver has seen me B. if he brakes suddenly i can see it an stop my self

also allowing enough room between the truck an you to stop is essential - im pretty squishy compared to the arse end of a bus

EKE_38BPM

I've done some research. I couldn't help myself.

From the Highway code: Thinking distance at 30mph is 9 metres
From Science of Cycling: Stopping distance on a bike on dry concrete (not tarmac) of a "bicyclist" (but it doesn't say what kind of bike, what kind of brakes, what kind of tyres etc is, but gives an answer of 10.4 metres. I think its fair to assume that that doesn't include thinking distance.
So, using those figures, the stopping distance of a "bicyclist" at 30mph is 19.4 metres.

UKspeedtraps says a lorry's stopping distance at 30 mph is 26.8 metres, so a "bicyclist" can stop in a shorter distance than a lorry can, but, if the cyclist is less than 9 metres behind the lorry when the lorry slams on the brakes, the cyclist will ride into the back of the lorry at full speed because they will not have reacted to the lorry braking.

Ouch!

notsoblue

Like BigMat says, you should be back and to the side if you want to draft. Bit silly to be right behind without being able to see anything ahead of the vehicle.

rick_chasey

EKE_38BPM wrote:

I've done some research. I couldn't help myself.

From the Highway code: Thinking distance at 30mph is 9 metres
From Science of Cycling: Stopping distance on a bike on dry concrete (not tarmac) of a "bicyclist" (but it doesn't say what kind of bike, what kind of brakes, what kind of tyres etc is, but gives an answer of 10.4 metres. I think its fair to assume that that doesn't include thinking distance.
So, using those figures, the stopping distance of a "bicyclist" at 30mph is 19.4 metres.

UKspeedtraps says a lorry's stopping distance at 30 mph is 26.8 metres, so a "bicyclist" can stop in a shorter distance than a lorry can, but, if the cyclist is less than 9 metres behind the lorry when the lorry slams on the brakes, the cyclist will ride into the back of the lorry at full speed because they will not have reacted to the lorry braking.

Ouch!

But you're always anticipating right?

I've drafted countless times and never been caught out.

Then again, I tend to stick to vehicles I can see through, or hang far enough to the right that I can pop my head around to see what's going on, or worst case, slip down the side if I'm going to run into the back of them.

jonny_trousers

Never really tried it, but tempted now. Most busses on my route, however, stink so I don't want to be anywhere near them.

EKE_38BPM

Rick Chasey wrote:

I've drafted countless times and never been caught out.

Yet.
Sounds a bit like the bloke who says its OK to clean his gun whilst its loaded.