It's likely you're going to come across this if you haven't already.
Let's look both at prevention and cure of cramp.
First of all make sure that the riders have an effective bike setup. If handlebars are higher, the rider can end up using calves more and larger muscle groups less. Coupled with incorrect pedalling technique you can be more at risk of cramp. Make sure the rider is not riding with toes pointing downwards – encourage riders to pedal so that...
Perfect for Christmas. Or UnChristmas. Whatever.
Give each rider gets a reindeer name (or double up if you’ve got more riders than Santa has reindeers - Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Donner and Blitzen).
When you call out a reindeer, that person has to attack, or climb, or whatever challenge you set.
If you call out ‘Rudolph the Red Nosed Reindeer’ everyone has to attack. We play this a lot over Christmas – and we have one rider who is referred to by everyone else as ‘Cupid’ all year round. It’s fun and it gets giggles.