If the roads are iced and you're not a fan of the mountain bike, you can always use a turbo trainer. Jodie Stimpson (jodiestimpson.co.uk), winner of the 2011 Virgin London Triathlon, recommends using programmes and setting goals to keep you engaged. "If it's possible, invest in a computrainer because the programmes on it can mix up sessions, you can set your own bike courses and race a computerised training partner. It keeps it interesting."
Stimpson used this approach when training for the 2011 ITU World Championships. "I set up a course that matched Beijing [where the grand final took place] so it had a hill, descent and flat, which made the hour fly and kept me focused on the session."
Hayes recommends longer reps when doing a turbo session in winter. "Try a warm-up of 10-15 minutes, then complete 4 sets of 15-minute repetitions, with 3-minute recoveries, or 4-6 sets of 10-minute efforts, with 3-minute recoveries. If you use a power meter you can come back each week and try to beat your best average watts. This will beat the boredom and give you some goals to smash."
Miles logged on the turbo or rollers can build a good winter base, but don't overdo it. Paula Dewar, BTF level three coach from V02 Maximum (vo2maximum.com), says, "If you let your cadence and heart rate drop, it becomes a junk session, and won't help you get faster. I wouldn't recommend spending over 90 minutes on the turbo."