Leg Cramping on bicycle rides over 40 miles

[SoCalSurfer]

For about the past month or two when I do really long rides on my bicycle my legs are cramping up. My quads are what cramps up.
At first it thought it was a loss of fluids but I drink at least 1 24oz bottle an hour with Skratch labs electrolyte mix in it.

When I am not riding I drink a lot of water and always have clear urine, so I don't think I am dehydrated before the rides. Ride day in the morning I have a large glass of water 16oz before I have anything else to eat or drink. Breakfast is 1/2 cup oatmeal and a banana and then during the ride I eat home made rice cakes about every hour. I am really at a loss of what could be causing it.

I weigh 260 and ride at a fast pace, 17-20mph with the group I ride with.
I don't have this issue on ride under 30 miles. I have a 100 mile ride coming up in Palm Springs in a few weeks so I need to get this nailed down.

thoughts and idea?

 

[robs2nd75]

Are you taking any vitamins, minerals, weight loss supplements? Are you cramping at any other time? If I recall correctly you are diabetic, is it still well controlled?

 

[SoCalSurfer]

I am taking Gene's stack. No other weight loss supplements.
Its the only time I cramp up and its only on the longer rides. On my 25-30 mile rides that I do by myself during the week I don't cramp at all.
I am diabetic and its well under control and has been for years. A1C is always in the normal range.

I was doing some reading and I think I just need to supplement during the rides with some salt type supplements. when I am done doing the long rides you can see the salt on my face and when I wear black my shirt. The Skratch labs stuff is really good I think I will mix it up a bit stronger and take a supplement for the next ride and see.
From what I have read it like to be not the lack of fluid intake but what I have is not replacing what I am loosing.

 

[Nelson Vergel]

Dehydration, low magnesium and electrolites can cause cramps.

 

[SoCalSurfer]

I might start taking a Magnesium supplement. When I got cramps taking Tums help work them out but the damage was done. it was a hard 20 miles to finish after getting them...

 

[robs2nd75]

Whenever I start getting cramps on a regular basis I double my multi-vitamin and ingest more sodium. Always seems to work for me. Are you, by chance, lactose intolerant?

 

[Gene Devine]

Dehydration, low magnesium and electrolites can cause cramps.

^^^^What the wise one said above.

I raced road bikes for years out of college and this happened to me as well.

Supplement with the highest quality magnesium supplement you can find and make sure your diet is rich in magnesium and other nutrients as well.

 

[Slate]

Magnesium. And before your ride you might want to take 8-10g of taurine as well.