Just do rides in blocks of 20 miles each, then you won’t get the cramps at 30 miles.
Hydration !!!
Assuming that your cramps are not due to lack of food and drink, take a look at your position on the bike. @Oldfentiger was having awful cramps until he had a proper bike fit done which sorted him out.
I’m fat for all my milesIf you're fat for 20 miles, that's 19.99 miles more than I am.
I’m fat for all my miles![]()
It's the same for all of us.
If we start out fast we'll blow up early.
We can probably all say "I can go at speed X, which is fast for me, but only for distance Y".
Actual values of X and Y vary from person to person obviously.
Take those 20 miles a bit easier and you'll be able to last longer.