Bicycle engines and the law
 

Hi all, I haven't cycled for many years as my commute to work is only a few miles, and after going through all the hassle of getting the bike loaded up (panniers) and putting on my helmet, clips, trainers, etc. and then changing into my work clothes, it's taken longer than it would have to drive by car (5 minutes, though there's a really steep hill on both my to and from journeys). I also got fed up of paying almost as much for bicycle tyres as for CAR tyres!

To cut a long story short, I'm interested in using my old bike more, and I'm really interested in getting a petrol powered engine. I was interested in electric bikes, but they are in my opinion currently next to no help - the hill I have to go up on the way to and from work is a killer, and electric bikes only give out 200 to 300 watts, which is almost useless. I want a bike engine that will give out 1500 watts when I need it, and then I can pedal when on the flat. I've seen these on Ebay for approximately £120 plus shipping, which is a steal: the only problem is, I believe it's going to be a ridiculous process to get this thing legal in the U.K., after reading an excellent article by Frank Auton here:
http://www.users.globalnet.co.uk/~pa...cc/arc0497.htm

One would be forgiven for thinking that the government doesn't actually want people to stop using their cars - the current laws around bicycle engines are absolutely ludicrous.

I weight 11 stone. I could quite legally weigh 30 stone (I presume they haven't made that illegal yet), and ride a bicycle down a hill at 40 mph. The energy contained in such a moving object is obviously far more than three times as much as the enegy contained in my and a bicycle with a petrol engine on it, going at 20 mph. (I don't particularly want to travel at 30mph as I know it's not a safe speed to ride a bicycle at - at least, not all the time. Once in a while when going down a hill is okay, but even then it's pretty hair raising, and I know that if a car pulled out in front of me, I'd go straight over the bonnet because I couldn't possibly stop in time, no matter how good my brakes were.)

The law treats petrol assisted bicycles as if they are somehow the same as a moped that weighs 80kg (or whatever the average moped weighs). Obviously they aren't. The average bike with petrol engine won't weigh more than 30kg.

So I'm thinking of being a criminal and breaking the law - I'm planning on buying a petrol engine, fitting it to my bike (I'm going to buy the type that's been designed so it fits in the triangle of the bicycle frame, instead of above the back wheel. I think this is a bad place to put it (because it makes the bike more top heavy and prevents you from using a top box on a pannier rack, or even using a pannier rack at all!), and hiding it by putting two big pieces of perspex or coloured plastic around the triangle of the bike frame, so at a glance you'll just think it's some sort of streamlining (I'll put some trendy bicycle accessory logo on it so that the police won't even notice it). I hardly ever see a police car when I'm driving my car any way, so I'm sure I could turn off the engine if (big if) I saw the police, and even if I didn't I doubt they'd notice it.

The question is: what sort of penalty would I face if I were caught? Let's remember that if I weighed 30 stone and could pedal my bike at 30mph, I'd be far more dangerous than if I ride a petrol assisted bike at 11 stone. I expect the police will give me a warning of some sort, and then I'll get punished far worse than a car driver who drives without insurance - who can only be fined £150 or something ridiculous like that.

Basically I'm advocating the use of petrol engines on bicycles to at least get a few more people on bicycles who otherwise can't face the hassle of hills, and arriving at work sweaty. If the current legislation were changed, far more people would use bicycles. We need bicycles that can propel us up a hill without any pedalling at all - I can't see why one would need to if the engine can give out 2hp - a human can't give out more than 0.75 for any length of time, so the engine should breeze up the hill. Electric motors are useless in this regard - they only give you a tiny helping hand, and the batteries weigh a ton.

For a commute of only a few miles/Km, and if you don't want to get "sweaty", you could wear your regular work clothes and walk the bike uphill.

I don't like the new little "motorbikes" we have here in the states(a current "fad", for kids and folks with too much money), and I assume you would use a similar engine-they are incredibley noisy(my gosh and annoyingly so). Here, the law applies to the size of the engine used-above a certain cc(?49) it's a motorcycle. I'd be a bit hesitant to use the statement "if the current legislation were changed, far more people would use bicycles..."-can't recall the last time I saw a moped commuter(again in the states).

What's a stone equivalent to?

Funny you should mention that. Saw one idiot riding one of these (electric?) 'motorbikes' on the sidewalk with pedestrians. I didn't realize at first it was motorized until I saw that his legs weren't moving and the bike was shaped very oddly.

I was half a heartbeat away from yelling at the idiot.

those little gas engines pollute more than cars. Yeah, the cheaper way would be to just push it up the hill.

You don't mention your gearing, but have you considered putting on a new cassette or freewheel (depending on which you have) with larger cogs?