Introduction

When you have narrowed down the field in your search for a motorcycle you will probably come home with a hand full of brochures or notes. One thing is for certain - there will be tables and tables of numbers. Numbers you need to know something about right? (We do not want to choose our motorcycle based on the colour only now do we?!)

The right engine capacity for you

This can range between 50cc and 1800cc. Generally, bigger capacity means big power, big weight, big fuel bill and big bucks. 

Anything below 250cc is considered a small motorbike. Anything from 250cc to 650cc, mid range; 650cc to 1200cc is a big bike while anything bigger than that is a monster!

Bikes bigger than 300cc are not suited to radical off road conditions as they are too heavy.

Pillion passengers should not be accommodated on anything less than 500cc if distance is involved.

Screaming, nimble performance is found between 650cc and 1000cc

Comfortable long distance road touring is found between 900cc and 1200cc

Comfortable long distance off road trial riding is found at 600cc.

Anything bigger than 1400cc is all style and attitude and is only found in cruisers. In cruiser design, big engine capacity does not translate into huge power or acceleration.

For radical off road racing or travelling an off road bike of less than 400cc is needed. This is especially true the faster you want to go.

A cruiser style tourer with a V twin engine. Note the tank bank and the leather and studs panniers. The large bag at the rear attaches to a vertical steel frame bolted to the bike - convenient, but ensure that only the lightest of items is in the top half of the bag.

How many cylinders?

You have a choice. You can either have the "growl, grunt and thump" or you can have maximum performance - but you cannot have them both. Fewer cylinders sound great and are associated with biker attitude and popular cruiser culture. Fewer cylinders however limit the motorcycle's maximum rpm. This impacts performance, acceleration, horsepower and torque at the top end of the rev counter. At lower revs however there is little to choose between 2, 3 and 4 cylinders - in fact 2 cylinders delivers more torque at low revs.

The fewer the cylinders in the engine, the more the bike is suited to trails, off-road and MX conditions because of the need for more torque at low revs.

The more cylinders there are, the more the bike is suited to long distances on tar road due to the increased smoothness of the engine.

Vibrations generally decrease with an increase in the number of cylinders. Important for long distance touring.

Screaming, howling performance is more characteristic of a four cylinder motorcycle where the engine is able to rev up to 10000rpm and beyond. 

Seat height

Ensure that the seat height allows you to reach the ground comfortably with at least one foot flat on the road surface. This does not sound that important but it is when you are riding at slow speeds, in traffic, on uneven road surfaces or in confined places that you will appreciate its relevance. Most bikes can be lowered a little so speak to your dealer. 

Cruisers generally have lower seats around 70cm from the ground. The average bike is 80cm while the off road motorbikes are over 90cm in height

How rake angle affects handling

Some motorcycles, especially cruisers have an amazing straight line stability. It is easy to point them in the general direction and open up the throttle. They are not so easy however to whip around the sweeping bends of a mountain pass at high speeds.

Other motorbikes by comparison, especially sportbikes are easy to throw from one curve into the next. Their handling however it twitchy and they have to be "driven" even when the road is dead straight.

This nimble handling characteristic (or lack of it )is derived from the rake angle among other things.

From "Proficient Motorcycling" David L Hough.
Bowtie Press. (see bike schools page)

The greater the rake angle the greater the straight line stability. The less the angle the quicker the handling response. In extreme cases a damper has to be fitted to a sportbike where the handling is so unstable as to be a problem. (See wheelbase below for more)

Generally sportbikes have a rake of 24 degrees while cruisers are closer to 30 degrees.

Wheelbase

Strongly related to handling and rake angle is the length of the wheelbase. This distance tells a lot about the intention of the bike designers as flickable, responsive handling deteriorates the longer the wheelbase becomes. Conversely put, the bikes straight line stability improves as the wheelbase gets longer.

Sportbikes have a wheelbase of between 135 and 145cm and naturally have the quickest handling characteristics. Sport tourer's wheelbases are between 146cm and 155cm. Dual sport (enduro bikes) are found in a narrow band between 147cm and 150cm. Big tourers and cruisers have similar wheelbase lengths of between 160 and 168cm and therefore display the greatest straight line stability.

Standard motorcycles  by definition have an a midrange wheelbase length of around 150cm.

In theory anyway a motorcycle with the same rake angle as another but with a shorter wheelbases will therefore be slightly more 'flickable' when it comes to riding those twisty canyon roads.

If you intend to travel long distances with a pillion passenger your motorbike should have a wheelbase of more than 150cm

Just how heavy?

The weight of a motorcycle is very important. For one thing it should not be so heavy that the rider cannot manoeuvre it in and out of confined spaces at the local shopping mall. The rider should also be able to pick it up should it fall over (and it will!!)

If you buy a bike approaching 220kg you will find that your wife/girlfriend will generally find it too heavy and will not want to learn to ride herself. The motorcycle will also be unsuitable for off road even if it has an off-road appearance.

Scooters are to be found at the bottom of the scale at 80kg. Most motorbikes fall in the 160 to 220kg range. Big bikes like cruisers and sport tourers can be anything from 220kg to 360kg.

Pay load (GVWR)

This refers to a bike's total weight carrying capacity i.e. rider, pillion passenger (if present) and gear. If you know that you will generally have a pillion passenger and perhaps camping gear, you will need to ensure that the motorcycle has the necessary permissible gross weight carrying capacity for your needs. Some 'big' bikes have a surprisingly low rating e.g. The Harley Davidson  FXSTD/1 Deuce and the Kawasaki Vulcan 1500 Drifter are both big cruisers. The HD can a take a payload of 200kg while the latter can only take 160kg

Compare the more upright ergonomics of this BMW R110RT to the Yamaha opposite. Note the higher rise of the handlebars relative to the seat, the shorter reach to the grips and the forward position of the footpegs. This results in the body weight being transferred to the butt. The full fairing displaces a lot of air thus protecting the rider from the wind blast.

Suspension

Suspension is a complex topic and varies greatly from bike to bike. 

Off road bikes have suspension systems with a lot of travel, maybe 27cm on the rear wheel. Street bikes have about 12cm of travel while some cruisers have very little offering a hard ride especially at the tail end.

Sportbikes have complex adjustable suspensions systems to match a variety of variables including tyre choice, weight of the rider and road surface.

More modern systems have a single adjustable monoshock at the rear while more conservative motorcycle designs have dual shocks with little or no adjustments possible.

Gear Boxes

Motorcycles designed for fast acceleration have 5 or 6 speed gear boxes with gear ratios closer together. This includes small Motocross bikes as well as sport bikes. These bikes have to be driven hard with frequent gear shifts.

Bikes designed for a more leisurely pace like tourers, cruisers and even dual sport bikes have a 5 speed box with the gears spaced further apart.

** Top of Page **

Special protective gear

Depending on the bike you chose there is protective gear specifically designed for that type of bike. This is particularly true for sportbikes and off road racing.

Torque and horsepower?

Sport bikes have high revving engines in excess of 10000 rpm while cruisers, touring bikes and dual sport are low revving engines offering maximum torque around 5000rpm. A basic understanding of the difference between torque and horsepower is a good thing. Follow this link for more **Torque/Horsepower**

Long distance road touring

A trip of 1500km should be done on a quiet bike with at least three cylinders, an engine of around 1000cc or more, a large windshield, full fairing and a comfortable moulded saddle. The bike frame should offer lots of space for a top box, panniers and a tank bag. The exhaust system should not obstruct the bike's payload capabilities. The wheelbase should be more than 150cm if you intend to tour with a pillion passenger.

Generally the quieter the motorcycle is the more relaxing for the rider after hours and hours on the road.

The longer the travel is on the suspension, the more relaxed the driver when touring long distances.

For touring, an aftermarket moulded seat is often a necessity. The larger the seat is, the more comfort it offers.

The more one is exposed to the wind, the more tiring the trip becomes. Many bikes have optional wind shields and fairings that offer more protection.

** Top of Page **

Big trail bikes

Motorbikes between 300cc and 650cc with single cylinder, four stroke engines are better described as trail bikes rather than off-road (also called thumpers)  They can easily handle sand roads, even well defined paths but are too heavy for very uneven rocky terrain that requires both speed and manoeuvrability. In short, they can handle anything that a general purpose 4 x 4 vehicle can when ridden by an experienced rider although deep water river crossing may be an exception to this. 

"Big trail bikes of more than 650cc are not trail bikes at all but tourers with a trail bike appearance."

This statement always causes some reaction from BMW 1100GS, 1150GS and 1200GS owners. It is true that well trained riders successfully ride difficult trails. Despite this, rallies like the Roof of Africa and the Paris to Dakar attract bikes of around 600 and not 1100cc. Careful reading of Ewan McGregors and Charlie Boormans much published round the world trip on BMW1150 Adventure bikes reveals that although the bikes were an excellent choice most of the time, they were too heavy when the roads ceased to be 'roads' and became 'trails'.

The off road event called the GS Challenge attracts large numbers of big GS owners. An unreasonably large amount of these riders however drop their bike (more than once) during this event.

Long distance travelers like Gideon van Oudtshoorn, Chris Scott, Nik Boseley and Simon Thomas all reveal in their own way that trail riding with bikes more than 600cc is not always the best choice.

** Top of Page **

Sportbikes

Modern sportbikes are a combination of high revving engines and lightweight construction. 

Bigger is not better! and sportbikes walk a middle road - usually four cylinders and less that 1000cc. This makes them smaller and lighter. They demand a crouched riding position to reduce wind resistance. Racing fairings and a small windshield further reduce drag and enable it slip through the air. Their lightweight frame and complex adjustable suspension are inherited directly from the race track.

Customisation is common but only to increase speed. The quest for ultimate performance brings sportbike riders together and biker clubs are a common phenomena. 

Cruisers  

Cruiser riders want a complete motorcycle package that makes a big statement. This package excludes performance but focuses on an attitude and a lifestyle. The bike is an holistic work of art combining colour, sound, texture and flowing lines.

Genuine cruiser owners never ride a stock bike off the showroom floor but customise it into a unique fashion statement. Ironically the uniqueness is to be found in a very narrow band of icons e.g. skulls, flames, leather and chrome to name a few.

'Hi tech' is not part of the cruiser package with everything from biker apparel to brake technology being from an era when things were a lot more simple and down to earth. All of this compromises rider safety a little  but this is OK  . . . the cruiser rider is aware of this and rides accordingly? 

Because this is a complete lifestyle-package riders who own cruisers are very gregarious, even more so that sportbike owners.

See dedicated Cruiser page for more

** Top of Page **

I would give you the sound of the pipes of this big American cruiser but that would destroy the download time! The rest is there from bandana to tassels.

Motocross

Light weight bikes (80 - 95 kg) built for speed and manageability. For this reason the engine may well still be a two stroke although four strokes are now quite common. Engine sizes fall between 125cc and 600cc with the bigger engines being more trail and enduro bikes than true motocross. The bikes are single cylinder because of the need for lots of torque at low revs

Non essentials are dispensed with to keep the weight down and therefore kick starters are still the norm. Few are street legal. Everything about these bikes is high i.e. seat height and ground clearance. Wheel rims are large i.e. 21" on the front and suspension travel long e.g. 30cm on the rear and 27cm on the front to soak up the rough terrain.  Seats are small and uncomfortable as they are mainly ridden standing up or for short periods of time. 

Fuel tanks are very small at between 7 and 8 litres. 

** Top of Page **

Ergonomics

The ergonomics of this Yamaha YZ600R shows us why it is a sportbike i.e. the higher footpegs, the flatter seating position and the longer reach to the handlebars. The fairing is designed to smooth the bike and crouching rider through the air causing as little displacement as possible.

Standing on the footpegs to negotiate a bad piece of road is not really an option with this style of sportbike.

(Diagrams from the January 2001 Edition of "Motorcyclist")

Helmets     Riding Safely     Protective Gear   Tyres     DIY     Touring    Motorcycle Articles

Top Of Page

Navigation Page