hot soak in epsom salt bath, use plenty, minimum 2 cups and I've heard of ppl using a lot more. I also like to add an aromatic bath soap like Dr Teal's Eucalyptus Spearmint which can be found at Walmart, drug stores, the Christmas Tree Shop & Amazon. Don't use the combo stuff, buy separate salt and bath soap, this way you can use a lot of salt and just a little soap. Walmart has the best price for epsom salt. soak for 20 min minimum. the magnesium in the epsom salt is a natural muscle relaxer. massage your large leg muscles and lower back while soaking. you can also take an oral magnesium supplement but take just a tiny bit, too much can cause loose stools. supplements before, during and after long rides such as calcium, sodium, potassium and magnesium can help reduce muscle soreness and cramping. a small glass of red wine while in the tub helps too, just don't fall asleep and drown.

good luck!