Wet roundabout with a cyclist and a blind exit
You are riding a 650 cc naked bike in steady rain on a two-lane approach to a large roundabout. Your speedometer reads 55 km/h in a 50 km/h zone and the road surface is glossy, with standing water in the right-hand wheel track. A cyclist in a yellow jacket is 15 m ahead of you, riding on the right edge of your lane and signalling left with an outstretched arm. Two cars are already circulating: one is in the outer lane level with your entry point, the other is in the inner lane approaching the exit just past your entry. Your front tyre has 2.5 mm of tread in the centre, and you braked hard yesterday on a dry road without incident.
1. What is your priority and speed plan in the last 50 m before the give-way line, and why does the cyclist change it?
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First, correct the speed: at 55 km/h in rain you are above the limit and, more importantly, above the speed at which you can stop on a wet, glossy surface. On a wet road, braking distance grows substantially compared with dry tarmac, and standing water in the wheel track reduces grip further. Roll off the throttle early and use both brakes progressively, avoiding a sudden grab that could lock the front.
Priority: traffic already circulating on the roundabout has priority. The car in the outer lane is level with your entry, so you must give way to it. The car in the inner lane is approaching the exit past your entry; if it stays in the inner lane it will cross your path only if it changes lanes, but you cannot assume that, so treat it as a hazard and be ready to stop.
The cyclist changes the plan because a cyclist signalling left on the right edge is likely to move toward the centre of the lane or into the roundabout. You must not overtake into that space. Hold back, keep at least a 2-second gap (more in rain), and let the cyclist establish position before you commit. If the cyclist enters the roundabout, you follow at a safe distance and do not squeeze past on the left.
2. How does the 2.5 mm front tread depth and yesterday's hard dry braking affect your decisions today?
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Tread depth matters most for water clearance. At 2.5 mm the tyre is legal but close to the limit, and its ability to channel water away is reduced, raising the risk of aquaplaning in standing water. You should therefore reduce speed further, avoid the wheel track with standing water, and use gentler steering and braking inputs. Consider having the tyre replaced soon.
Yesterday's hard dry braking is a reminder, not a guarantee. Grip on dry tarmac is far higher than on wet tarmac, so the same brake pressure today could lock the front wheel. Squeeze the lever progressively, let the fork settle, then increase pressure. If the front locks, release and reapply smoothly. Keep the bike more upright through the roundabout and avoid braking while leaned over on the wet surface.
3. The cyclist enters the roundabout and stays in the outer lane. What line do you take and what do you watch for?
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Stay behind the cyclist in the outer lane until you can see clearly that the inner lane is free and that no vehicle is about to cross your path to exit. Do not overtake on the inside: a cyclist in the outer lane may drift outward or be forced wide by a car exiting.
Watch for: the inner-lane car's indicators and lane position, any vehicle waiting at the next entry, and the cyclist's head checks. Keep a gap of at least 2 seconds, larger in rain. Signal your exit in good time, check the mirror and blind spot before moving out, and accelerate only once you are past the cyclist and the exit is clear.