A Guide to Motorcycle Modifications: Part Three – Wheel In The Changes

April 24th, 2015 | In: Custom Bikes, Modifications

Whether for cosmetic or dynamic reasons, changing the wheels on your motorcycle can be one of the most rewarding experiences. Both in the way that it makes the bike look, and in the way that it rides too.

In as far as performance gains are concerned, aftermarket lightweight wheels or, indeed, later model factory fitment wheels can give gains in acceleration, quicker turning and improved suspension performance. Remember, modern wheels are significantly lighter than those produced even a handful of years ago.
And, for older models, they also give the opportunity to fit gripper and stickier and, perhaps as notably, popular (ie easily available and more competitively priced) rubber.
And this is the very reason why we see later model cast (or forged) aluminium wheels fitted to bikes such as big air-cooled Kawasaki and Suzukis. But we mustn’t ignore the fact that many people opt for different wheels for stylistic reasons. A bike from the Eighties, with an eighteen or nineteen inch front wheel, and maybe even a fifteen or sixteen inch rear (certainly on ‘factory custom’ bikes) will not only benefit from the improved traction of modern seventeen inch radial tyres, but also look a damn sight cooler with the newer wheels and rubber. And a set of contrast-cut, anodised and polished rims add as much style and poise to a factory cruiser as carbon fibre or magnesium race wheels do a race-rep.

Expensive new wheel
It looks fantastic, and is easy to fit, but a wheel change needn't involve the cost of this billet beauty

But a wheel swap, despite its advantages, isn’t without its issues.

Starting with the simplest and easiest – although not necessarily the cheapest – we have bikes with spoked wheels that can simply have a different rim laced on to the hub. This is the principle behind most supermoto conversions in which a motocross, enduro or trail bike has it’s off-road sized wheel rims (normally 21” front and 16” rear) replaced with slightly wider 17” diameter rims. As the standard hubs are retained, the standard brakes, whether they’re drum or disc, are still used, and the only real issue is whether there’s enough chain clearance at the rear, as an ex-dirt bike will usually only have just enough room to squeeze in a 150 section tyre, although occasionally a 160 section will fit.

Spoked wheel
Spoked wheels are the easiest to change rim size, with just a caliper bracket adaptor needed on this 17” conversion

The end result of a supermoto conversion is a bike that has a lower seat height, has quicker steering, and enough cornering grip to create some serious footpeg / tarmac interference issues. And is more fun than a weasel in gym socks.

The extremest form of upgrading in the tyre width stakes is one that is especially popular on the other side of the Atlantic, and also has a few followers in Europe too – that of  the fat-tyred sportsbike. A 240 section tyre is common and thought of as being the sportiest option, although 300 or even 330 section tyres are being used. Occasionally a 360 section ring will be fitted, but they’re really not recommended for anything with a power output capable of pulling the skin off a rice pudding.

Fat sportsbike tire
Going as big as this at the rear will mean more than just a couple of new spacers...

Although tyres wider than those on an average saloon car can be used, it’s the radical ‘wagon wheel’ hoops that’re currently proving popular in the US of A, particularly in the current fad of baggers. They’re not especially wide in section, but boy are they tall! Wheels as large as thirty inch diameter rims are being used at the front, which means that, even with off-the-shelf bolt-in wheels, there are further issues in the form of clearance between the wheel and bottom yoke, meaning that some suspension modification will also be necessary.

Big wheeled bike next to small wheeled bike
This shows just how much of a difference a big wheel makes to the aesthetics!

While actually fitting different wheels into the standard forks and swinging arm isn’t generally much more fuss than changing the bearings to suit the axle, or using spacers to account for any difference in size or width, further issues can occur, for example at the rear thanks to swinging arm clearance, and chain alignment and clearance.

The internal width of a swinging arm is only really going to be a problem if you’re attempting to shoehorn a 180 section rear tyre into a skinny single cylinder bike. Chain clearance is far more likely to be of concern. Offset drive sprockets can be acquired, and rear wheel cush drives / sprocket carriers can be machined to suit, but you also have to be aware that the lower rear frame rails may be in line of the intended chain run too. It’s something of a juggling act, but far from an impossibility for anyone with a engineering bent!

Motorbike swinging arm
An aftermarket swinging arm is often the easiest way to fit a later model rear wheel into a twin shock chassis

There’s also the factor of brake discs. If the standard forks are being used, standard discs may not fit the new wheel and, in turn, the standard calipers probably won’t fit either. It’s not so much of an issue at the rear, as a standard caliper hanger can be modified to suit, or a bespoke one fitted.

Motorbike rear disk brake
Aside from wheel spacers, a new caliper mount may be needed

At the front it’s rather more complex, but it can be resolved by using bespoke caliper brackets. Although, of course, it is an issue that doesn’t exist if you happen to be fitting a complete front end, which is something that we’ll be looking at next time…

Bespoke caliper brackets on a motorbike wheel
Some clever engineering may be needed if a variety of components are to be used

 

IMPORTANT NOTE: It’s essential to speak to your insurer before you make any modifications to your motorcycle so you can understand the policy implications. Some modifications will dramatically increase your premium, and other modifications might make it very difficult for you to find a company that will insure you at all. Failure to disclose any modifications can also result in your insurer refusing to pay out on a claim, especially if the modification contributes to the claim.

Always do your research properly, consult an expert, speak to your insurer and make sure you’re fully informed of the risks involved of your proposed modification. Modifications should always be done to a professional standard and maintained appropriately.

 

Spending a childhood in the Isle of Man was only ever going to have one result – a lifelong fascination for motorcycles of all types, that pervaded each and every moment of his waking life. Self-claimed as a ‘motorcycle anorak’, Dave Manning’s particular penchant is for the daringly different, the wild and wacky, the cool and custom. Modified is where it’s at, whether it be classic or brand new. Standard is for showrooms.

Want to read the full modifications guide? Just click on the links bellow!

Part One of A Guide to Motorcycle Modifications

Part Two of A Guide to Motorcycle Modifications

Part Three of A Guide to Motorcycle Modifications

Part Four of A Guide to Motorcycle Modifications

Part Five of A Guide to Motorcycle Modifications

 

Please note, Devitt are not professionals in bike modifications, so before you decide to make any changes to your motorbike we do advise you to carry out thorough research and always speak to your insurance company to find out your policy implications.

  • Jonny

    Eeek ! Try telling your insurer you’ve just modified your bike by putting different wheels and brakes on it !!! Not so straight forward (or cheap !)