Solid Forks 2 Sus. Forks

I've fitted suspension forks to a few bikes, once I used a high end set but usually fit the ones like you pictured. I think they are known as Zoom forks and come fitted to average quality supermarket bikes.

The zoom forks are usually 1" threaded and most modern forks are 1 & 1/8 non-threaded. These different setups are not easily interchanged. Also 1" threaded forks of high quality are rare.

I'll try to answer your questions as best I can:-

Q. Is thread-less forks better then threaded forks? And what has to be changed to go from threaded to thread-less?

A. Threadless is newer tech and has a larger diameter steer tube. Thread-less forks are available in more choices of travel, construction and cost. You can get adjustable damping, lockouts, different springs ect.

You will need a bike frame that takes a 1&1/8 steerer to fit them or cut the threadless steerer of your new forks and press in or braze on a 1" threaded steer tube (what I did). You could also order a custom made set or change the bike frame.

Q. How do I go about choosing the right suspension forks for my bike?

A. Research the MTB sites. It depends on your riding style though. The zooms are fine for pavement. You might want a better set for off road though. Get them with disc mounts.

Q. How do I correctly measure my forks and what to measure to get the correct suspension forks.

A.Fork measurements include terms like trail and castor. Also their length is important. I'm no expert on bike geometry maybe someone else here can expand. Heres a link with some info.
Fork Lengths, by Damon Rinard. Carbon forks and steering geometry changes.

Q I have been told that going from solid forks to suspension forks will screw up the angle of the forks and make the bike not handle, is this true?

A. Depends on frame and fork geometry, In my experience, using a MTB originally fitted with straight forks then swapping to suspension forks increases length giving slower steering witch is a good thing at higher speeds. Results will vary with cruiser frames I guess. The only way to know for sure is to try it.

I went from solid forks on my cruiser delmar to suspension forks from a roadmaster mountain bike and they fit perfect,maybe a little longer but steers just fine and i now have front brakes and front suspension. i also changed my rear coaster brake wheel for a mountain bike wheel,a little wider but got it to squeeze inbetween the rear frame,this wheel is quiet and my wide cruiser peddal chain fits one of the right side gears on the wheel, i still use it like a single speed. Even my cruiser tire fits the mountain bike back wheel.

The only situation where I would not want a 1" threaded fork is for rough, off road riding. It's easier for the handlebars to get out of alignment with fork.
I use a 1 inch threaded suspension fork on the road with no problems.

The short story is, unless you can come by an old Marzocchi coil and oil fork (real suspension fork) with the old 1" threaded tube, the only thing even worth considering is one of the Schwinn type springer forks (no damping but they use your weight to counter against "topping out" too fast).

All the Walmart type 1" slider forks suck and have no adjustment, and may even come apart
Failure of top-out washer of Pacific bicycle suspension fork -- photos

Dave i have used threaded and threadless on my cruiser, measure the outside diameter of the fork stem, if its 1 1/8 then your frame wil support a variety of 1 1/8 threadles forks and if you fit it together the only thing i needed was a couple of spacers, i used the old frame races and the new fork races and i have never had any problems and its always tight. if your stem is a one inch than you are probably going to have to find a decent cheap set of threaded forks that work just fine, they still do the job the only problem i have had is that they wear out cause my bike only has front breaks and its hard on the fork seals. Good Luck