Sponsor Le Jour de France for a chance to win a Bryton GPS

We like a madcap challenge round these parts, and Mike Davis and Stewart Pratt have dreamt up a neat one: to head over to Brittany and inscribe a massive ermine spot (that's the heraldic symbol on the region's flag, fact fans) with the GPS trail from a 480km, one-day bike ride.

480km is a long old way in a day, 300 miles in old money. It's going to take grit and determination. And probably a bit of crying and swearing if our experience of long-distance events is anything like the norm. But it'll be worth it: Mike is raising money for mental health charity Mind and Stewart has chosen homeless charity St Mungo's as his cause. And if you donate to either, you'll go into the hat to win a Bryton Rider 20 GPS worth £100 from us. How? Here's how.

First, make a donation to either St Mungo's or Mind, and be sure to add your Twitter handle to the comment Then tweet it using this link Make sure that the hashtag "#LJDFroadccSchwag" is included in your tweet: without that, you won't be entered into the draw.

If you haven't got a twitter account, just make one for the comp. It only takes two ticks and you don't have to use it again. If you follow @lejourdefrance on twitter from your account we'll enter you into another draw to win a pair of road.cc socks. We have three to give away. Both draws will take place after Mike and Stewart have finished the ride: you have until Sunday 30 June to make your donation or follow the boys on twitter. Good luck to them, and get donating!