Originally Posted by Skewer
How important is wheelbase for load stability? Does it make a huge difference? I am trying to choose between using a 1982 model year steel bike that I have toured with before, which I know carries a load well, but has very old components, including 27 inch wheels and down tube shifters, and another 1998 model year steel bike I have which has newer components but a slightly shorter wheelbase. The 1982 bike has about a 40.25 inch wheelbase and the 1998 bike has about a 39 inch wheelbase. For comparison purposes, I noticed that the wheelbase on the new Trek 520s are about 41.5 inches.
I know there are lots of other considerations besides wheelbase, but I am wondering how much differerence wheelbase makes when it comes to stability?
Think of the bike as a rather elaborate leaf spring. The longer the leaf, the smoother the ride and the better able the bike is to handle loads. The cost of this better ride is quickness. For example, a short wheelbase bike will respond quickly to rider input and will steer and ride like a bug-eyed Sprite (an Austin Healy sports car). It's going to be a lot of fun for zipping around town and for short trips. A long wheelbase bike will ride more like an old Cadilac. It won't respond that quickly to corners and it certainly won't be a sports car but it also won't beat the crap out of you.
To continue the car analogy, if you are going across the country with all of your stuff, the sports car isn't going to be comfortable. With all your stuff, the car (or bike) will need constant attention to keep it going down the road and not running off into a ditch. Hit a bump and that sporty ride is going to translate it right up your spine and you'll be worn out by the end of the day.
The Caddy is going to glide over the bumps and soak up the roughness. It may not have sporty handling but the handling will be predicable and not need constant attention to keep it moving down the road. In other words, you can relax and enjoy the trip.
For touring bike, a 39" wheelbase is pretty short. You probably have 16" chainstays on the bike. If you don't hit the bags with your heels, you must either be mounting the bags as far back as possible or you have tiny feet
Moving the bags rearward will move the center of gravity of the bike further back and make your bike even quicker steering...not something you want on a loaded bike
