h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

When I were young a big bike was a 500 - 650cc motorcycle. Anything bigger was considered huge.

A medium sized bike was a 250 to 350, with anything less being smallish.

Big bike riders did not look down on smaller bike riders. Each to his own, likes and pocket.

There was an era when the medium bikes ruled the roost. The bike to have was not a car size engined monster but a Yamaha 350 that could see much else that was on the road.

Today I ride a medium sized motorcycle, by today standards. It has a 660cc single cylinder four stroke motor. Oh how we used to laugh at the poor Panther with its enormous 650cc motor.

Is all this for the better?

Well, it certainly is for the manufacturers. I doubt if the cost of manufacture increases with size as much as the selling price does.

Today the choice of motorcycles between 125cc, the learner size, and 600cc is probably in single figures. Honda still have a 250cc road bike, there are some models from China and Korea, and of course the Enfield 350/500s from India.

This is a consequence of the motorcycle being promoted as a 'leisure' vehicle. One which requires the rider to be outfitted in a full leather suit and regularly in our climate waterproofs. Also a helmet fully covering the head is a must. Getting this lot on for a ride on a Sunday is fine, but everyday to work? Easier to get in the car.

I have never ridden in full leathers. I normally wear an open face helmet with goggles. Of course I wear waterproofs when needed, over my normal clothes. As for the helmet. After a few scares on wet days with a steamed up full face, not to mention the sunny days with no peak it was back to the clear vision and shade of my open face.

Since being retired at 50 my only commuting since has been a year I spent on a university course. Got paid for doing a one year MSc course! Before the axe fell I commuted for around 20 years, the last few involving over 40 miles a day. Always from the suburbs, or latterly the countryside into a city. Compared with the car journey my journey time was half, or less. I also had parking at no cost right outside my place of work. On wet days I was always dry under my suit, unlike my car driving compatriots who ended up wet with the walk from a distant car park.

I have never really understood why my colleagues never wanted to understand the benefits I accrued through motorcycling to work. These included: setting off later, getting home earlier, no parking problems, smaller running costs. When the weather was not the best for two wheels I always had public transport as a backup. Even when we moved further away I made sure the railway was not to far away. In fact cycling to the station and then taking the train into the city was not quite as quick, or as convenient as the motorcycle but was definitely better than using a car.

Has the motorcycling industry ever sold on these benefits. Well, there might have been some half hearted efforts, but generally, no. probably because they felt that trying to attack the perceived danger was too difficult. Better to sell over powered machines to born again bikers, who then started killing themselves a bit to often at the weekend.

As an engineer I can appreciate the Triumph with its 2200cc motor for its technical prowess. Personally I would liked to have seen the efforts applied to a nice everyday 350cc machine capable of 100mpg.

There has recently appeared a chink of light in the form of the super scooters. 250 - 400cc machines with automatic gearboxes. Even so size has raised its ugly head with machine of up to 650cc appearing as well. Accompanied of course by the usual press platitudes that such machines are to be preferred to their smaller brethren.

Once again though they are promoted as an alternative leisure vehicle and not as a means of reducing traffic levels on the daily commute to work.

In a few years my 660cc machine will become a bit to big. I will then revert to a 125cc machine. If such sized machines worked for me when the traffic densities were less than today, then on todays crowded roads I will be King of the road to the end of my days.

I know this sounds like a bit of a rant, but it is a serious question. Should not motorcycling be promoted on smaller machines as a means of reducing road congestion and the carbon footprints of traveling.

Thanks for reading.

I can agree that for commuting to work a smaller or "mid" sized bike would most likely be more benneficial to someone who doesn't do much motorway commuting. For leisure purposes I'd still go with a bigger bike espsecialy if going two up.

You'd think that if the goevernment (red Ken and such) were that really concerned about congestion then they would be promoting bikes and biking for commuting to work on the very points you've raised. Instead all we get from government is more and more measures trying to get more people off bikes (and out of cars though less so) and onto public transport which more often than not is overpriced, overcrowded and inconvenient.

I also used to commute to work on a bike (and in a car when the weather was really bad) but as my work was not in the centre of town to commute by public transport wasn't an option.

I think more could be done to promote biking as a good alternative to the car when commuting but no-one from the government is going to do that.

There are numerous 125, 150 and 250 cruisers. But most ofthe major manufacturers have actually stopped doing them, in fact Honda and Suzuki are the only big manufacturers, aside from Kymco but they're notin the same league, whom I can think of that still make little cruisers and for people like myself cruisers and scooters are the only option.

I see the problem as motorcyclist organizations always reacting to government policy. MAG was created because of the helmet law, and were a total failure. The BMF seams to promote bikers riding machines with worse green footprints than most cars. Then they wonder why they are not taken seriously.

Now I am an individual member of the BMF and on the whole they do a pretty good job on promoting my interests. However, there is this blind spot on size. No doubt a psychologist might be able to explain it. Motorcyclists are spending their time justifying machines that twenty years ago would have been outright winners of any motorcycle race or have engines of a size greater than many family cars.

I think that size has to be an issue when promoting utility over leisure use of bikes.

MAG were hardly a total failure. They may not have suceeded on the helmet law, but it was very unlikely they would. On the other hand they have very much been instrumental in bloking type approval, the 125bhp cap and the eu noise legislation. Lets not have a 'my rights group is better than yours' thing here. And yes, I am a member of MAG, although not particulkarly active in the social scene.

For many years there was a voluntary bhp cap on bikes between the big four, but that got blown out the water quite a while ago with the triumph 1200 with 150bhp.

It's also worth noting in the debate on size the impact that the super sports 400 had in the early 90's where suddenly you had small bikes capable of the same sort of speeds as much bigger machines. And that was down to the size limits of the japanese home market.

For general riding I find the most telling factor to be torque. And small bikes just don't have it. Although I've noted a few v-twin 250cc chinese bikes of recent and not sure what they are like.

Torque is a function of the efficiency of the engine. So a small engine, breathing well and burning the fuel efficiently will produce sufficient torque for the needs of the rider. Torque at high revs at the engine is converted to torque at low revs at the rear wheel by means of the gear box.

Power is the torque multiplied by the radial velocity of the motor.

As for MAG, my national bike club gave them the boot a few years ago. The matter comes up at every AGM and the vote is always an overwhelming majority against re-affiliating. Around 80/100 to 1, maybe 2 if Dennis has a mate present.

I must admit no personal experience of MAG so I can only go on what others tell me and MAGs own promotional efforts. Nothing I have seen of the latter suggests I am being fed porkies by those with personal experiences, negative and positive.

The BMF always seems promote a more professional aura. From what I understand this has been maintained in spite of the internal squabbles. I feel it is a bit like deciding on who to vote for at an election. Rather than which one is the best, which one will be better for me in spite of all their faults.

As for bike sizes. I reckon a 350/500 is more than big enough. It is the predominance of car engined monsters that could ultimately be the undoing of motorcycling as we know it. Hopefully others pressures shift the trend downwards before the bureaucrats and politicians do.

That Dougie Lampkin is the greatest motor sport champion in the UK is undeniable, and generally unknown.

He rides a 250

http://www.dougielampkin.co.uk/machine.htm

OK, firstly torque as a function of engine efficiency is a bit disingenious since any power output of the engine is necessarily dependant on the efficiency. A more efficient version of the same engine may well output more torque. Or not. So we can pretty much ignore that and assume we have an 'efficient' engine, whatever that may mean.

Which brings me to my second point which is that 'efficiency' and 'sufficient torque' are relative terms and undefined in your argument. Which means that you are making an assumption behind your argument which may not be the same one I am making. So we could actually agree but since I don't know what you mean by 'sufficient' nor 'efficient' I can't tell. 'for the rider' is also a bit hazy since each rider is different, so this will also change the meaning behind your argument.

But putting that aside, the torque an engine develops is down to the surface area of the pistons, the force exterted on those pistons by the combustion of the fuel and the radius of the crank. Hence why a big V-Twin develops more torgue than a similar sized in line 4. The power is indeed calculated by the rotational speed (not radial velocity) times the torque. (there's other clever stuff done with exhuasts - eg the EXUP valve and ports and so forth ).

"Torque at high revs at the engine is converted to torque at low revs at the rear wheel by means of the gear box"
What the gear box does is to trade speed against torque. So in low gears we have higher torque but lower speed, so we can get up hills and accelerate faster. Whereas in high gears we get less torque but higher speed so we can zoom along nice and fast on long flat sweeping roads.

"That Dougie Lampkin is the greatest motor sport champion in the UK is undeniable,"
No it isn't. Which means that the argument predicated on it is thus questionable at best. And anyway, it's a trials bike so completely different design requirements for a road machine.

"It is the predominance of car engined monsters that could ultimately be the undoing of motorcycling as we know it."
I'd have to disagree with that.
It is attitudes that could be the undoing. Attitudes of those in power who see motorbikes and their riders as apart from the rest of society, attitudes of those who ride being either apathetic in the pursuit of their rights or pessimistic about the future and having a 'do it to ourselves before someone else does' stance. And lack of responsibility on the part of those who use public roads as a race track or stunt arena. Plus those who revel in the outsider identity and don't want to lose it.

Having said all that
"Rather than which one is the best, which one will be better for me in spite of all their faults."
I agree with totally. And the peterborough rally used to be really good in the days I went to really big rallies.

Torque is the force applied multiplied by the distance from the force to the centre of rotation. In an engine this force is generated by the pressure of the combustion process. Technically known as the BMEP or brake mean effective pressure. For a given size of engine for a given BMEP the torque will be the same for a long stroke or a short stroke variant. Power is the radial velocity multiplied by the torque and as short stroke engines have the ability to rotate faster than long stroke engines they tend to be the more powerful engines.

Radial velocity is the correct technical term. RPM is the more common term, but in the power equations pi and 60 are there to convert the rpm to radians per second, the unit of radial velocity, to be multiplied by the torque so that the value of power is derived.

This is why the modern trials bike is a short stroke engine. Torque is a function of the BMEP and with a good gear box the higher revolutions of the engine are translated to effective torque at the back wheel.

When people refer to a 'torquey' engine they mean one that pulls at relatively low revolutions. With modern computer controlled ignition and fuel injection not quite the difficult trick it used to be. A well designed short stroke four cylinder engine can be more 'torquey' than a big single. My 998cc Toyota Yaris with fuel injection and computerised ignition pulls happily from around 1000 rpm. My 660cc single cylinder Yamaha engined bike with a carburettor and electronic ignition control needs around 2500 rpm to pull away.

It is an unfortunate fact that the majority of popular literature on the topics are very much dumbed down.

I'll apologise first. I'm writting this at the end of several night shifts. It may not present itself as intended.

When it comes to bikes beating the queues then smaller is better. However, longer journey's mean that a bigger bike makes it easier for the rider, bet less economical on the wallet.

It's us, the buying public that is the drive behind what is being sold. If we don't buy, then there's no profit in making it.

I want a multi purpose bike. Something that is fine for the 10 mile commute to work through town but, that also tempts me into turning that commute into a 50 mile trip so that I can blow the cobwebs away. I don't mean three figure speeds either. Just a ride in the country, sometimes sedate, sometime pacey (yeah, maybe a touch on the illegal side too). It needs to give me some weather protection, but I don't want to be coccooned like when I drive the car. If it also allows me to throw a ton of luggage over it and tour europe, yet turn back into a sport/tourer role when I get there, great.

I thought the VFR800 would be my ideal for that role, and it is....up to a point. The fuel consumption I consider to be poor,. ranging from high 30's mpg on the TT circuit, to low 50's cruising. That's not bad for a modern bike but when I think that my 70's Four4 would get up into the 80's touring and rarely, if ever, dip below 50 when tripping the light fantastic I think it's poor for a modern bike (especially when you consider two of the selling points for injection fuelling, economy and reduced pollution).

I don't need it to do 150mph+. If I use that performance I will surely lose my license (that could be the least of my concerns). I'd happily trade some of that top speed for increased mpg.

One last point: Whatever the size of the bike, there's far less tarmac needed to park it up than ANY car. Considering the price of land in the larger cities you would think councils might latch onto that thought. Imagine the profits they could make.

G'night all

"Torque is the force applied multiplied by the distance from the force to the centre of rotation"
I'm glad we agree.

"Radial velocity is the correct technical term. "
No it isn't, rotational velocity is, unless you're dealing with astronomy. But it is a common misuse. It also has SI unit of radian per second.

"Technically known as the BMEP or brake mean effective pressure. For a given size of engine for a given BMEP the torque will be the same for a long stroke or a short stroke variant."
Um, but that's because the torque is used in the calculation of the BMEP. So if BMEP is the same, and the displacement is the same then the torue *must* be the same since you are talking about the same theoretical engine!
The reason that the stroke makes little difference is that BMEP is calculated on displacement, which is bore x stroke. So if the displacement is the same and the stroke is shorter then the bore must be bigger. Which means what you lose on the possible crank radius you gain in available piston head area for the force to act on. Although, of course, stroke is not really any indicator of crank radius.

"Power is the radial velocity multiplied by the torque and as short stroke engines have the ability to rotate faster than long stroke engines they tend to be the more powerful engines"
The assumption implicit in that argument is that the torque is the same. As power is indeed torue times rotational velocity, vary EITHER of them and you will vary the power. So yes, higher revs with the same torque will produce more power, but equally higher torque with the same revs will also produce more power. Smaller engines usually rev higher, but larger engines have more torque (due to increased capacity and increased crank radius).

"with a good gear box the higher revolutions of the engine are translated to effective torque at the back wheel."
Yes, exactly what I said. Although I'd say 'traded' rather than translated.

"My 998cc Toyota Yaris with fuel injection and computerised ignition pulls happily from around 1000 rpm. My 660cc single cylinder Yamaha engined bike with a carburettor and electronic ignition control needs around 2500 rpm to pull away."
Well yes, the car is 300+cc bigger and tuned for midrange and bottom end. What's the red line on each of them?

Let's try a BMEP calculation using this Montesa (250cc, 18.7 bhp at 7000 rpm,2006 model) and my own bike (Honda CB1000, 998cc, 98 bhp at 8500rpm, 1995 model). Bearing mind of course that mine is a road bike and his is a competition trials bike, and both tuned for their respective environments.

BMEP = (bhp*13000)/(Displacement in litres * revs of max output)
His: 18.7 * 13000 / .25 * 7000 = 138.9
Mine: 98 * 13000 / .998 * 8500 = 150

So even a modern race bike can't match the power output of my 10 year old, generally considered underpowered, road bike.

"It is an unfortunate fact that the majority of popular literature on the topics are very much dumbed down. "
Very true. And some of the mechanics text books make the same mistakes. Best to work from the physics.

Knowing that I do get my terminology terms a bit out I thought I would check. We are both wrong. The correct term is angular velocity!

I do not know if the world is yet for ready for vehicle specs to be written in the correct SI terminology. Mind you I think that kW and Nm could be used more. Most manufacturers brochures quote them. As Watt and Newton are both British there is a nationalistic element that should be employed.

Back to the small bike big bike argument.

I managed with a 150cc machine as an all purpose machine. Commuter, week end runs, rallies and continental touring. Often two up with camping gear. Now that I no longer have to commute I find the big 660cc a reasonable all rounder, although it is not as convenient for just popping into town as smaller bikes were. On the open road the greatest advantage of the bigger engined bike is to go up hill without slowing down.

Except to bypass towns and cities I tend to avoid motorways. I can read a map so have traveled the length of this island avoiding motorways as much as possible. Not to difficult, and much more fun.

Fair enough, as far as I'm concerned both rotational and angular velocity are correct terms. But hey, it really don;t matter that much and I dunno why I was being so arsy above.

Back to the bikes.

On the issue you raise, I do think that the commuter bike should be pushed a lot more. When i was learning and growing up in my teens and 20s your bike was for commuting, having fun, doing rallies, trip down to the shop, everything. And most of the people doing this didn't have a fortune to spend. And I guess that is why things like CB550s, Z650s, GPz550s and so forth were so popular, cheap and do anything.

I dunno, I do think there's mileage in the idea but I don;t think it should be against the larger bikes.

Maybe take a leaf from the car industry where everyone wants an Aston Martin (or whatever) but the most popular car is the toyotta corola. And mondeos seem to be ubiquitous in certain areas.

I think it all boils down to two basics factions in motorcycling;
Practical motorcyclists, for whom riding a motorcycle is part and parcel of everyday life, and;
Fashion Biker or 'weekend warrior' for whom riding a motorbike is a fashion statement.

The requirements of both types are, IMHO, poles apart and there's the rub. The differences will never be reconciled, as each looks for something different in motorcycling. The practical motorcyclist will be prefectly happy with a fairly utilitarian machine of modest capacity and own it for a long time. The fashion biker must have the latest thing that suits his/her particular style and will be happy until something newer comes along.

Naturally, the manufacturers prefer the fashion biker, as it means they will sell more stuff. The poor old practical motorcyclist has to make do with a dwindling pool of useful machines.

I see what you're saying, but I don;t think it works. I've ridden bikes since I was 17 (mid 30s now) I used to use them all the time but economics forced me onto the train for work. That's just to give my background.

I've known long distance dispatch riders who use 750cc sports bikes (one had a 100thou+ zxr 750 when I knew him in the 90s). I know die hard bikers, with no car, riding things like modern z1000s or hayabusas. I think your binary definition is missing a category - bikers.

RUBs will have the latest wizz-bang zzcbfjrr-xj1900xxsp1. But then so will some bikers. Practical bikers which I'm not sure how you defined but to me means someone who just wants something that gets A to B reliably and cheaply will either be a) constrained by cash and would buy something a bit better if they could or b) commuters who aren't bikers at all and usually go for scooters or, heaven forbid, BMW C1's or c) bikers who keep their main machine for recreation and run a hack.

As for dwindling pool of practical machines - don;t agree with that at all. There's loads of mid range commuters - look at all the ER-5's on the second hand market. And gt550s/750s and CB550s and bandit 600s. and so forth.

My Twopenneth,
I've got two bikes, a CB350F, Which I rode every day since I got it in 1978, to last august (I hope to get back on it soon) and a 98cc chinese scooter, which I am limited to through Ill health, (I can't get my leg over, I've got a slipped disk...).
The scooter is just about keeping me sane.
The Honda is not a "Superbike" but it picks up a quickly as (or quicker than)most cars, Is cheap to run, and will go at 20-30MPH faster than the speed limit on a motorway.
Why would I want a 1000cc plus engine?
Big bike small tap?

I've been thinking lately about whether or not I should buy the sv1000s or something like it. I still have the sv650s, and it's a great little bike for riding to work on, but I'm over 6' and 90kilos+ and the 650 wobbles like Aunty Hilda's bosoms when I'm trying to go at any pace up Mt Glorious. Most of the time, handles beautifully, grunty enough to zip off from the lights and suprise bigger bikes...but a couple of times when I've pushed it around a corner and made a mistake in shifting my weight the 650's suspension has not handled it at all. This is scary, because Mt Glorious is after all a mountain, and typically has steep drop-offs on the outside of corners, of varying height but invarying in their ability to inflict pain.

I have a feeling the 1000's suspension might be better, maybe feel a bit more solid with the extra weight. Now - before you cry out that I could just upgrade the 650's legs - of course this is not the only reason I want the 1000: the problem is that the 650 is *just* grunty enough. Sure, it's possible to get one wheel in the air, but I miss the rush of a bigger engine.

And yet the 650 is a great bike. So I haven't got around to going to the dealer just yet....

I remember things in very much the same way as the author of this posting. My first 'big' bike was a Velocette Venom (500cc) and would it go! I wouldn't ride one now, even if I was offered the opportunity because modern bikes are so good, and I am still attracted to great design.Performance is relative. I have recently, however, reviewed my own attitude to riding. When I ride 'the' bike I wear armoured fabric clothes, which are much better than those of yore - no towel to stop the water down the neck for starters!The FJR 1300 is a force of nature. A marvel, but, is it what biking is, or should be, about? Probably no. I started commuting by scooter a year or so ago and had to put waterproofs leggings on about 4 times this winter... such a different experience from my youth. Oh, I admit it's a 600cc scooter, but it does it all. I've been forced by circumstances to ride large distances on it, yet find it light and flickable, and most important easy to park on pavements and such. The seat is spectacularly comfortable and it easily covers more than 40 to the gallon, and 140 to a tank. I am ignoring the car because I can wear almost normal clothing... and the bike is more convenient despite the occasional wet day. M&S now offer Stormwear jeans at £25... and the footboards mean ordinary shoes can be worn. Setting off the twist and go gearbox hurtles you forward, and 600cc will carry 2 people at 85 with plenty in reserve. What more do we need?

How can anyone assert that the BMF offers a professional image? It is in chaos, chaos which is self inflicted by its management. MAG was the rascal of the national clubs, but is now mainstream, although it isn't exactly showing it at the moment.

First of all the BMF. Internal problems do not mean the end. It has also maintained a reasonably constant face. I now think things are under control and sense is starting to prevail.
I am involved with a voluntary organisation, larger than the BMF in terms of finance and employees and we had similar problems with certain individuals following their own agendas. It took some effort and we saw them off and since then everything has improved.

As for size, 40 mpg !!! My bike manages 55 to 60 and our car 50 mpg.
How can motorcycling be taken seriously as an alternative to cars when 40 mpg is considered good? By the way, 50 mpg is petrol after 110000 miles. The diesel version does 60 mpg.

Reading a car magazine in the supermarket I noticed that the latest Smart car with a 750cc 45 bhp diesel manages 80+ mpg. As it did not perform like a formulae 1 car it natrually got slated. Now a 45/50 bhp diesl in a bike frame might not lap the TT at 130 mph but could probably manage 100+ mpg. A mile post that any manufacturer could be canny enough to plug, but will they.

Never managed a Velocette 500. Had a 200LE for a while. Mini Goldwing!!! but being ex police was knackered. When it went it was fine. Unfortunately Velocette went bust while I had it. Had to giv it away to get rid of it. Mind you those were the days when I couldn't consider a Vincent for a £100. Isn't hindsight wonderful.