maddogandnoriko

I recently bought a used adult tricycle, I think it was cobbled together. Anyhow, went to grease the steering bearings and the fork threads were stripped. I proceeded to make it worse by forcing the nut on. The tires are 20" and the tube is 1", the forks are curved. I would like to apologize now for any incorrect terms I am using, it has been 20-25 years since I have been near a bicycle.

So obviously I am looking to fix my new toy, asap. Can I buy a used 'bmx' type kids bike and and put the straight forks on? If I do what will the ramifications be, if any? And what should I watch out for? I also know the brake set up will differ, but I have a set of cantilever brakes to switch with.

Thank you for your time,
Todd

HillRider

Forks are "raked" so the dropouts are somewhat forward of a line through the center of the steerer tube. Rake can be obtained in two ways, first by curving the fork blades as your now-defunct fork was made or second, by attaching the fork blades to the crown at an angle. Either method can give the same results.

maddogandnoriko

So essentially either will be the same? Just asthetics?

HillRider

Yes. The amount of rake, measured in mm, for either type can vary depending on the designer's intent, but the conceopt is the same.

dsbrantjr

I think that on a tricycle the amount of rake on the fork is less critical than when trying to balance on two wheels. Steerer compatibility and esthetics may be the deciding factors in this case.

fietsbob

I'll guess you need a longer steerer tube on the fork, for the trike
than cannibalizing a Kids BMX bike offers.

maddogandnoriko

Fletsbob- I bought a junker an found this out the hard way, thanks for the help though.

I am shopping online for forks and am bufuddled by the numbers I am seeing. Maybe some one can help me out. I need 20" forks with a steerer length of 6 3/4 from top to bottom of race and 1" steerer tube O/D.

I looked at bike parts USA(and a few other shops) and saw numbers like these: 185x100x21.1x27.0BK.

Could someone please explain what those mean, so I can order the correct part?


Thank you for you for your patience,
Todd

fietsbob

Bike shops will be helpful , walk into it and let them help.

100 is normal front fork tip width for the hub.

Other than that, no idea without seeing the dimensions on a blueprint graphic.

Al1943

Not sure what threads you stripped but think that a machine shop should be able to chase the threads.

Kimmo 

Or - as on BMX forks, simply mounting the dropout on the leading edge of the tube.

As fietsbob said, 100mm is the standard front hub OLD (over locknut dimension). I suspect that fork has a 185mm long steerer. The 21.1x27.0BK is likely the steerer diameter and thread pitch, but I'm not sure how those work. If you can verify it's standard BMX 1" threaded, and your current fork's steerer is shorter or equal to 185mm, you're good to go.