I want to run a marathon, is biking a good substuite?

Question

I know running is the most important think to get me ready for a marthon but sometimes after i run my knees hurt a lot, so i've been biking between 15 and 20 miles a day, will this hurt my over all performance if i replace a day or two a week with biking instead of running?

Answer 1

It won't hurt your performance.

A road bike, plus rides with the road club will increase your lung capacity and endurance.

Riding with the club, you will be pretty safe; and, that's a fun sport all on its own.

You also may become interested in the Triathlon sport that way.

For the ultimate in knee relief, check out combining "shoe attachment" with "spinning" because this is where you are lifting the opposite leg (just enough to lift its own weight) while the "working" leg is merely resting its weight on the pedal. . . alternating left and right, of course. . .going on at about 95 rpm, yet no force on the knees. It is sort of like trying to keep your feet off the pedals. . .one at a time. . .very, very quickly. ;)
Shoe attachment isn't required, but without it, the pedals sort of feel slippery when there's no pressure on them (that would be one at a time, whenever a pedal is at the top 12:00 position).

I mention this because while you're "resting" on the bike, it might as well be spinning a road bike, truly giving your knees a break, cycling with others, enjoying the trip. . .

As far as exercise goes, 15 to 20 miles on a bike is about like a trip to the grocery store. Even the elderly road cyclists go from 30 to 50 miles. Well, that is about the same as 15 to 20 miles of mountain biking on gravel and whatnot. But mountain biking won't give your knees a rest because those lose traction if you "spin" pedal.

Lastly, put the seatpost up, up, up too high so that you know what that feels like and then lower it back down so that you have comfortable leg extenstion. I mean, of course, that you should have the seat into the right place within the hour.

It is just that a slightly too low seat will harm knees, and as far as height goes, the only thing you can tell about it is: "You never know if you have enough till you have too much."

I mention that because knees are sensitive to seatpost height differences as small as 3/16 of an inch. So, crank it way up and then put it back down about 1/4 inch at a time--until you have found the sweet spot. . .then mark it with a sharpie or bit of white paint.

A seat too far forward and/or long cranks will make a pain at the front of the knee, sort of inside the lower part of the kneecap. The cure for both is moving the saddle rearwards 1/4 inch. If it happens again next time, go for 1/4 inch more. (rearwards = farther from the handlebars)
If necessary, and it usually is, install a shorter extension handlebar stem to compensate. About 80mm (previously a standard) is quite relaxing to "reach" with no loss of speed.
My favorites are the Profile Designs stems from 60mm to 90mm. Although if you end up with a 60, then you know for sure that your bike is too large. ;)

So, protect your knees with good cycling fit and habits. Chances are that you can get a good lifelong sport out of the deal.

Answer 2

Sure.

I ran a couple marathons and cross training on my bike was part of my training regimen.

Be carefull though. I got creamed by a car and broke my leg on a day I was giving my knees a "rest".

All better now.

Answer 3

in biking your lungs wont expand much while in running its your lungs which expand so i dont think its a good alternative.