SPROCKETS, CHAINS AND ALL THAT JAZZ

Nothing beats a good old grilling, so we fired a few extra questions at the B&W boys on chains, sprockets and everyday maintenance. Here’s what they had to tell us…

FB: How often should you change a chain and sprockets?

B&W: There’s no categorical answer to that one. It’s a pretty individual case with some people achieving over 20,000 miles from a chain in some instances. In reality, the more you maintain a chain, the longer it will last you. That means regular adjustment and lubrication. As a result of doing so, you’ll also prolong the life of your sprockets. One thing to note is that if you change your chain it’s good practice to change your sprockets at the same time. Otherwise you’ll be coupling worn sprockets on a new chain, or vice versa, which will exaggerate wear on the new component.

FB: Rivet links vs split links – which is for what? B&W: Any bike over a 125, assuming we’re not talking of MX bikes, should be fitted with a rivet link. The truth is that a split link simply can’t cope with the stress and strain forced upon it by bikes of any potency, so they’re likely to fail, which in turn will lead to a chain failure. That’s not a problem you want to have so don’t ever be tempted to fit a split link if it’s not appropriate for your bike.

FB: What’s pitch got to do with it?

B&W: Pitch refers to the size (width) of a chain. Manufacturers produce their bikes with a specific pitch in mind, designed to cater for a particular model’s power and the nature of the machine’s purpose. Typically speaking, the bigger the pitch, the greater the rolling resistance, which is why trackday riders and racers tend

to reduce the pitch of their chains. For instance, a litre bike will probably come fitted with a 530-pitch as standard, but most race bikes get converted to 520-pitch, as there’s less mass to move around and less area in contact, which will reduce frictional losses.

FB: How do you work out gearing ratios and why are they important?

B&W: By altering the number of teeth on the front or rear sprocket you’ll alter the rate of acceleration and wheelbase of your motorcycle. If you reduce the number of teeth on a rear sprocket it will give you taller gearing, and slower acceleration. But when you reduce the number of teeth on the front sprocket, it has the opposite effect – giving you lower gearing and sharper acceleration.

To work out what ratio you’re running, simply divide the number of teeth on the rear sprocket by the number of teeth at the front. This will give you a figure to work with as a reference – a gearing ratio. Once you’ve got a gearing ratio you can work out how to achieve finite enhancements to your gearing, possibly changing both, just the front, or even just the rear to achieve the maximum performance you desire – which is particularly helpful on track.

FB: Can you re-rivet a used chain?

B&W: Yes you can, but only if you have that specific chain’s exact rivet link. Rivet links aren’t universal, regardless of whether they’re the same pitch or brand, so never make that mistake. With this in mind, it’s never a bad idea to buy an extra rivet link or two when you purchase a new chain – you never know if you’ll need it.