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20" wheel

I have a P-38 with a 17" front wheel. The front fork on this bike has a shock absorber. Can this fork be changed to accept the newer 20" wheel? If this can be done, would there be any negative effects fromt the modification?

The fork you have now cannot be used with the 20" (ISO 406) wheel, because there will not be enough room for the bigger wheel to squeeze in. If you want to use the bigger wheel, you will need to buy a new fork from Lightning, or some other front fork with a fairly long (say 10 inches or so) 1" threaded steerer tube. I think a new rigid 20" fork from Lightning will cost around $200, but you will have to contact the factory directly to make sure. A new 20" shock absorbing fork will be more money.

The main advantage of the larger wheel is that it will give you a somewhat smoother ride than the smaller wheel, and this means you can crank a little harder and go a bit faster. There is also a much wider selection of tires in the 20" size, and they are easy to find. The 17" (ISO 369) size is kind of an oddball, even by recumbent bike standards.

The main disadvantage (other than the obvious cost in $$$) of the 20" wheel is that it will make it harder for height-challenged riders to plant their feet flat on the ground at stops. Shorter riders take note.

So what should you do?

You already have a shock absorbing fork. If it is working properly (see the Lightning website for maintenance tips), it should already give you a smoother ride than a rigid fork with a 20" wheel.

The Lightning shock absorbing fork is nice, at least when it is adjusted properly. It is only a little bit heavier than the Lightning rigid fork. Most other shock absorbing forks are boat anchors.

So if I had your bike, I would not make the fork switch. Just buy an extra tire or two in the 17" size to keep on hand, just in case you destroy your present tire.

Safe riding,

So Joel, 20 inch rides a bit smoother, but with shock absorbtion
about the same smoothness as the 17.

How about speed differences? Climbing differences? And slow and high speed handling differences?

thanks in advance for you input.


This is one of the things that recumbent cyclists love to obsess about. Endlessly.

Should I switch from a 16" ISO 349 wheel to a 20" ISO 406 wheel? Should I switch from a Schwalbe tire to a Continental tire? Should I replace my older 7 speed components with newer, up-to-date 9 or 10 speed components? Shimano or Campagnolo or SRAM? And so on and so on forever...

My advice: the differences we are talking about here are subtle. They are so minor that you have to pay VERY CAREFUL ATTENTION to notice that there is really any difference at all.

As a venerable ancient Greek philosopher (was it Plato or Aristotle?} said:

"The harder it is to tell the difference, the less difference it makes."

If you ride rougher, less-well maintained roads, suspension (and fatter tires, the poor man's suspension) will make a real difference for the better. A larger front wheel will help, but only a tiny bit.

I would just ride the bike the way it is. Do not mess around with component and wheel and fork choices. Focus on getting comfortable on the bike, and getting used to the way that it handles. Make sure the brakes and shifters work smoothly and reliably. After all, this is your very first recumbent bike. You started out with a classic machine. Smart move.

At some point, perhaps when the weather gets nice, you can try to improve your athletic performance. Keep track of your speeds on a favorite regular course, and try pushing yourself. Maybe do interval training if you really want to work. Find a group of riders you get along well with, and who are a little bit faster than you. That can make you work harder than you might when riding alone.

The only thing that will make a MAJOR difference in bike speed, other than the performance of your motor, is putting a fairing on the bike. Either a factory-made F40 fairing, or something you build yourself. Playing around with different sized front wheels, different components, so-called aero wheels, and the like... I guess some people think it is fun. But it is AERODYNAMICS that really count. The rest is just the (usually trivial) details.

There is a good book addressing these questions called BICYCLING SCIENCE by David Gordon Wilson and another guy named Whitt.

I will now descend from my soapbox.

Safe riding,

i'm taking my OCD medicine now. ha. I am kind of a gear head and love tinkering, but i'm sure that's the norm, hardly unusual. but your advice is grand. i shall take it to heart.

Comments forthcoming after receipt, assembly and a few hundred miles.


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