Cycling cramps

[Critch]

Hello, can anyone help. I currently cycle for fitness and after around 20miles I start to get cramps in both legs. I take Hydro SIS vitamin B tablets before ride with water and during ride to try to help stop dehydration but the cramps are still there. I stretch before and after ride aswell.
Does anyone else suffer the same and is there anything that works to help prevent these cramps when doing longer cycle rides?

 

[MrsA2]

Have a look at perhaps increasing magnesium?

 

[SimonP78]

I used to get cramps when I just drank water on anything over about 60km, I used to talk little salt packets out with me to deal with it, but have since switched to using electrolyte tabs in my water bottles (I rather like the Wiggle own brand lemon ones if you're in the UK) for anything that will take more than about 4h and (touch wood) seems to be fine now as long as I remember to drink. I did a hundred mile ride last week when it was fairly warm and only drank one 750ml bottle each way (with electrolytes) and had no hint of cramps.