Hello all

What is the relationship between frame geometry, speed, and comfort?

I am touring on a vintage mountain bike with an enormous wheel base. The chainstays are quite long, the distance between the front of the rear wheel and the seat tube is almost twice the width of my hand.

The bike is incredibly comfortable. Fits me like a glove. Perfect body posture, everything.

But, I'm slow. Way slower than I ought to be.

I noticed this in a sort of a controlled experiment, when i first got the bike. I would ride with a friend who wasn't in very good biking shape. She rode the same bike, a hybrid, every day. I would ride my mtb, a 1983 Diamond Back Ridge Runner, or a vintage Raleigh 12 speed road bike.

I without a doubt went faster on the Raleigh. WAY faster. With way less effort. And I've noticed this to be true in all sort of different scenarios, the feeling that I ought to be going faster when on the mtb, but not knowing exactly why.

My own, completely unfounded theory, is that the mtb is so comfortable because the frame is designed to absorb shock. And there must be something about the frame geometry, what with the wheel base and all, that makes it harder to engage the right muscles to go faster with less effort. (???)

But I'd love a better explanation!

Thanks!