Differences between 2 wheels and 4+

[SammyTheSnake]

After mentioning it in another thread, I thought I'd start a bit of discussion of what's different between bikes and other vehicles. Having never driven anything larger than a white van (and that was only for a few yards to get it out of somebody's way) I can't comment on artics and such with much authority, but I know there are those here who can, so I'll leave it to them

Most bike riders have a fairly good idea how cars drive, through driving them themselves, or at least seeing them all the time on the road, but the same isn't really true the other way around.

The aim of this post is to help car drivers appreciate something of what it's like to ride a bike on streets populated more by cars than anything else, hopefully giving an insight into how bikes behave on the road and why I'm not really intending to go into the aspects of bikes that don't affect how car drivers perceive them (gears, brakes, etc.)

Anyway, here are just the first few things that spring to mind in the hope that others will contribute.

Size: a bike can squeeze into or through gaps that no car driver should contemplate. Some bikers seem to forget that a lot of the time it's the safety zone around the vehicle rather than the vehicle itself that takes up the space, but the fact remains that bikes can nip through a gap that a somebody used to cars wouldn't think much about.

Acceleration / Braking: the power/weight ratio of even a modest bike (like mine) will leave the average car red-faced some distance behind (I can do 0-60 in about the same time as a Lambo and I have what is occasionally refered to as "A bi t of a Girl's bike") and this can again easily challenge the expectations of those who're thinking in terms of larger vehicles. On the braking side, the same applies to a point, but it is limited somewhat by balance, it's pretty easy to get an ABS equiped car to stop in something pretty close to its theoretical minimum distance, the same is not true of a bike as the slightest loss of grip has a large effect on balance.

Balance: A car doesn't often have any difficulty balancing, but a bike rider has to pay a lot of attention to balance and this is of course intimately linked with steering. If I want to slalom back and forth, I can't do it in much less space than a car, because I have to countersteer*, and the sharper I want to steer, the more countersteering is needed. Also, in windy conditions, a car will have only minor difficulty maintaining a straight course. A bike can easily need the entire width of a lane in gusty crosswinds.

Visibility: A bike, simply because it's small, is easier to miss, visually, than a car. Add to that the fact that the shape of the bike doesn't trigger the danger response of the human brain as readily as that of a car. Add to *that* the fact that most people are thinking "Car" while driving (and artics etc. are hard to miss!) and many people therefore don't register bikes (or pedestrians for that matter) as quickly as they register cars, simply because their brain isn't looking for them as actively.

Leaning: When a bike corners, it leans into the corner, up to about 40 degrees can be expected on the road (more is possible, but rarely advisable) and this affects their visibility further, as the height of the bike is nearly halved! Also, the headlight is designed for upright operation, which means a bike can inadvertently (and unavoidably) dazzle a road user on the outside of the turn, or have less-than-perfect illumination of the inside of the corner.

There are probably a hundred other things that are relevant, but that's hopefully enough to initiate a bit of discussion

Cheers & God bless
Sam "SammyTheSnake" Penny
PS yes, I have insomnia. Great served with Lurgie

[manilva15b]

Well done Sammy.

I would also add grip. Cars have four tyres of flat profile, whereas bikes only have two rounded tyres. This means that bikes only have 1/4 of the amount of rubber on the road. Super-sticky rubber compounds can increase grip (anyone know how much?).

Bike tyres are designed to cope with the enormous accelerative and decelerative forces placed on them, which is why they last such a short time, as short as 2,000 miles though 6-8 thousand is more the average.

Also because bike tyres are rounded, the grip available is pretty constant (ignoring multi-compund tyres) even when leant over. The same is not true of cars where loss of grip is very significant if one or more tyres lift during cornering. The effect is that bikes can corner at quite high speed relative to the amount of tread on the road.

Poor driving conditions however, can drastically reduce the grip available to bike tyres - how many bikers are out there in the snow and ice? Where I live it all too common to see inexperienced scooter riders steam up to roundabouts, bends etc. and lose it. The lucky one's manage to regain grip after a serious wobble, the unlucky fall off - probably right in your path if you're a car driver. See the 'Danger is also behind' video posted this morning as to the stopping distance a fallen rider has - very short!

The point of all this is that motorcyclists need just as much space as a car, their safety zone is larger relative to the size of vehicle. Give them the space!
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[SammyTheSnake]

Well done Sammy.

I would also add grip. Cars have four tyres of flat profile, whereas bikes only have two rounded tyres. This means that bikes only have 1/4 of the amount of rubber on the road. Super-sticky rubber compounds can increase grip (anyone know how much?).

Many road tyres on bikes are quite capable of cornering at 1g, which is about the same as you're going to get out of road tyres on a car. I have cornered at a leaning angle of about 40 degrees on numerous occasions and have never felt that grip was an issue in those circumstances. On the other hand, I wouldn't do that in wet weather

One factor that goes the other way, interestingly, is that bikes are far less prone to aquaplaning than cars, due to the curved surface of the tyre and higher typical pressure (my rear tyre takes 40psi, for example) which allows them to cut through the water when a wider, flatter, lower pressure tyre would start aquaplaning...

Bike tyres are designed to cope with the enormous accelerative and decelerative forces placed on them, which is why they last such a short time, as short as 2,000 miles though 6-8 thousand is more the average.

I get about 6000 miles from my rear tyre (Bridgestone BT45) but my front tyre seems to last much longer, more like 15,000 miles.

I remember the first time I replaced my rear tyre, there was very heavy rain right when I was trying to wear off all the release compound (they recommend 100miles of dry driving before using any power while leaned over) Out of curiosity, I tried some power while setting off from a traffic light, while sat in a puddle about an inch deep. Even with the most adverse conditions above freezing, I managed a wee wheelie, so there's something to be said for the soft rubber

Also because bike tyres are rounded, the grip available is pretty constant (ignoring multi-compund tyres) even when leant over. The same is not true of cars where loss of grip is very significant if one or more tyres lift during cornering. The effect is that bikes can corner at quite high speed relative to the amount of tread on the road.

I have multi-compound tyres, so theoretically, I can do even better...

Poor driving conditions however, can drastically reduce the grip available to bike tyres - how many bikers are out there in the snow and ice?

I think the significant factor here isn't actually the grip, so much as the balance. As I mentioned in my post above, loss of grip in a car is far easier to cope with safely, whereas loss of grip on a bike can rapidly lead to a complete loss of balance. How many car drivers oversteer and end up unhurt? How many bike riders end up tipped off the bike in the same circumstances? Remember also that many bikers also have cars and are wusses in cold weather

The point of all this is that motorcyclists need just as much space as a car, their safety zone is larger relative to the size of vehicle. Give them the space!

Absolutely.

Cheers & God bless
Sam "SammyTheSnake" Penny

[manilva15b]

Some interesting points. As you've probably guessed I've ridden bikes , from a C90 to a VFR 750.

I get about 6000 miles from my rear tyre (Bridgestone BT45) but my front tyre seems to last much longer, more like 15,000 miles.

I remember the first time I replaced my rear tyre, there was very heavy rain right when I was trying to wear off all the release compound (they recommend 100miles of dry driving before using any power while leaned over) Out of curiosity, I tried some power while setting off from a traffic light, while sat in a puddle about an inch deep. Even with the most adverse conditions above freezing, I managed a wee wheelie, so there's something to be said for the soft rubber

I forgot, I was referring to rear tyres only. Your wet weather antics (I've never pulled a wheelie) remind me of giving the VFR too much fist away from a roundabout and fish-tailing the bike for about 50 yards Something I've never achieved in a car.

I think the significant factor here isn't actually the grip, so much as the balance. As I mentioned in my post above, loss of grip in a car is far easier to cope with safely, whereas loss of grip on a bike can rapidly lead to a complete loss of balance. How many car drivers oversteer and end up unhurt? How many bike riders end up tipped off the bike in the same circumstances? Remember also that many bikers also have cars and are wusses in cold weather

That would be me then. Out here I have a Kymco Venox 250 (cruiser style) which hibernates when the rain comes. Then again, if you've seen the storm drains in Spain...