Why a Chain Is Worth Ten Minutes of Your Attention

A chain is the cheapest, most exposed and most neglected part of most hire bikes. It has one job — to turn engine output into forward motion — and it does that while sitting in road spray, grit and rain. When it is clean, correctly tensioned and properly lubricated, you will barely think about it. When it is dry and slack, you will feel it in every gear change, and in the worst case it can snap or jump the sprocket at speed, which locks the rear wheel.

The good news is that chain care takes about ten minutes and needs no special skill. Whether you have hired a 125 for a weekend or a big tourer for a fortnight, a quick check before you ride and a tidy-up afterwards will keep the bike feeling sharp and save you an awkward phone call to the hire company.

Start With the Handbook, Every Time

Manufacturers do not agree on chain slack. Some want 20mm of movement, others 30mm or more, and some shaft-driven or belt-driven machines need none at all. The handbook in the top box or under the seat is the final word, and hire firms usually keep a copy with the paperwork.

• Slack figure: usually given as 20–30mm, measured midway between the front and rear sprocket.
• Measurement point: most handbooks specify whether the bike should be on the side stand, centre stand or with the rear wheel off the ground.
• Chain type: O-ring, X-ring and plain chains need different lubricants. Never fit a chain you have not checked fits the sprocket pitch.
• Service limits: the handbook will tell you how far you can pull the chain off the rear sprocket before it is worn out.

If you are unsure, ask the hire company before you set off. It takes thirty seconds and it protects you. Fiddling with tension without knowing the correct figure is how people wreck chains and wheel bearings.

Checking Tension and Wear Properly

Push the chain up and down at the midpoint of the bottom run. You want a firm but noticeable amount of movement — enough to feel a clear gap, not so much that the chain slaps the swingarm. Then rotate the rear wheel and check again in three or four places, because chains wear unevenly and a tight spot can hide a loose one.

While you are down there, look along the chain from behind the bike. It should sit square on the rear sprocket, with no sideways kink. Hook a finger under the chain at the back of the sprocket and pull gently: if you can lift it more than a few millimetres and see daylight underneath, the chain is stretched and it is time to tell the hire company rather than keep riding.

Look for stiff links too. A seized link will not bend around the sprocket, and it will make the whole drivetrain feel rough and lurchy.

Cleaning and Lubricating Without Making a Mess

Clean first, lubricate second. Spraying fresh lube onto a gritty chain just grinds the grit deeper into the seals. Use a dedicated chain cleaner or paraffin on a stiff brush, work along the bottom run, then wipe with a rag. Take your time — a chain has around a hundred links and every one deserves a pass.

• Do it after a ride, while the chain is warm. Warm metal lets the lubricant creep into the pins and rollers.
• Apply to the inside of the chain, on the run between the rear sprocket and the bottom of the loop, so centrifugal force pushes the lube outwards through the links.
• Rotate the wheel backwards and spray a steady line. One full revolution is plenty.
• Wipe off the excess and let the bike stand for ten or fifteen minutes before riding.
• Keep it off the tyre, rim and rear brake disc. Lube on a tyre is a crash waiting to happen; use a rag as a shield behind the chain.

Avoid using old engine oil as a cheap substitute. It flings everywhere, coats your rear tyre and collects grit. If you are caught out on a long trip with nothing else, a light smear will get you home, but clean it off and do the job properly when you can.

Adjusting Tension and Keeping the Wheel Straight

If the slack is out of spec, loosen the rear axle nut, then turn the adjusters on both sides by equal amounts. Half a turn at a time, then recheck. The adjuster marks on the swingarm are a rough guide only — use them to keep the wheel straight, then confirm by eye that the chain runs true on the sprocket.

Once you are happy, hold the adjusters in place and torque the axle nut to the figure in the handbook. This matters: an under-tightened axle can shift under acceleration and a rear wheel that steps sideways mid-corner is genuinely dangerous. If you have no torque wrench and no handbook figure, tell the hire company and let them do it.

A straight wheel also means a straight chain. If the wheel is cocked, the chain wears fast, the sprockets wear on one side and the bike can feel vague at the rear.

If Something Feels Wrong, Stop and Report It

You are riding someone else's bike, so the rules are slightly different. If the chain is dry, slack, kinked or making a rhythmic clunk, do not nurse it for another two hundred miles — pull over, check it, and ring the hire company. Most will talk you through a quick fix or swap the bike. A chain that fails at motorway speed can lock the rear wheel or whip through the crankcases, and neither is covered by a cheerful shrug.

Keep a small can of chain lube and a rag under the seat, check the chain before each day's riding, and re-lube after wet or dusty runs. Ten minutes of care turns a hire bike from something you tolerate into something you actually enjoy riding.