Front Fork Suspension

[spdas]

Aloha, All. OK educate me.....

For my Whgelchair driving pod, i have BMX 16" wheel front fork with suspension. There seems to be no damping, only springing, so there is a hard thud on the rebound. Before i take it apart, do some of the cheaper "BMX" forks come only with springs and no shocks? If there is no shock, any ideas to minimize the harsh rebound? (maybe install a short tailgate/back window shock/spring from a car?)
thanks
francis

 

[dogman dan]

Yes, the economy fork is just a spring, no oil, no damping. They are often called pogo stick shocks. No way to upgrade this kind of shock.

Since a shock fork for a 16" wheel is a bit of a rare item, It might be that you are stuck with the harsh ride, but at least it beats a bent wheel, with some fork travel.

 

[Chalo]

I can't think of any conventional suspension forks for wheel sizes under 26" that have dampers. The next best thing I can think of is Ballistic forks with elastomer springs, which have a small amount of inherent damping.

There are suspension forks from Moulton bikes with 16 x 1-3/8" wheels, but they aren't cheap or straightforwardly compatible with non-Moulton bikes.

You might be able to remove the shock and swingarm from a BOB Ibex trailer and transplant it onto a sort of leading link arrangement.

Gas springs from car hatches won't work. They have spring and damping rates that are way too high, and little means to dissipate the waste heat you'd generate trying to use them as shocks.

 

[spdas]

Ok, this be a big "never mind" as youtube shows me the different types of suspension. Mine seems to be a cheap-ass one that resembles a Ballistic 600 XL, no shocks. I will just need to make and replace the "non-existant" upper bushings with new ones and call it a day.

Update. The top bushings are mostly non-existant. Making new ones will do the trick, (until i upgrade my entire front forks). But what material to use?? At Hone depot, there is a PVC coupling 1.00 x 1.25 which is perfect, but

Do you know of a different material (like UHMW or more sliding than PVC) that I could use......off the shelf, not at a plastic supply store.?

thanks Francis

 

[amberwolf]

If there's clearance, you could take a good fork for a 26" wheel and add clamped-on dropouts (cut off a non-shock BMX fork perhaps, along with the tubing they're welded to, split and then placed on either side of the fork legs).

I did something like this once to get a 20" fork with suspension, and though it wasnt' a very good suspension, as mine was just the pogo stick kind, it was a bit better than not having any at all, at the time. For mine, I welded rear dropouts to the front edge of the fork legs, because they were cheap and steel.

But just about any good fork is gonna be aluminum legs so you can't really do that on them. But you can clamp them on with U-bolts or other types of clamping.

The original dropouts and extra leg length would just need to clear the ground.

 

[Lurkin]

I hate cheap shocks with a passion. I've experimented with foam sections, rubber bungs, filling with oil and/or water... long story. All were ineffective at fixing the lack of damping in cheap forks. All I achieved was wasting good materials and money.

I have and would replace a nasty, cheap, damping lacking fork with a fixed fork and plusher, larger tyre any day of the week. Yes, efficiency loss from larger tyre run softer is the price paid. But the difference in comfort is notable and the suspension is effective, reliable and cheaper than a fancy fork. 8)

 

[dogman dan]

OK, I agree with all that.

Where do you get that better fork in 16"?

Are any better forks around in 20"?

AW may have the best idea. Take a semi decent 26" fork, and put home fabricated dropouts on it that clamp to the tube. As long as the bottom doesn't drag the street.

 

[Lurkin]

I'd be looking to folding bikes if you were dead set on it, but I still doubt you are going to find something affordable and of a decent quality....

 

[motomech]

The PO might look at Chinese scooter forks, very affordable and they appear to have damping rods.
I couldn't find stearing stems, but they must be on the site somewhere.
http://www.motopartsmax.com/index.php/main_page/index/cPath/268_166/tID/3

 

[spdas]

Aloha, the chinese scooter fork is a great tip. thanks. I got my forks fixed (somewhat) by making a bushing for the top of the "pogo stick"

thanks again.

 

[motomech]

While speaking of scooter forks, some 1980's scooters(Honda Spree) and the "No-peds" (Honda Express, Yamahopper, etc.) used a couple of table-spoons of grease w/ a plunger/bung to add a bit of viscosity to the damping.

Some folks that wanted a "real" fork w/ damping would "graft" a set of forks on the Spree stearing stem;
http://hondaspree.net/wiki/index.php5?title=Front_Fork_Change_for_Spree_to_Elite_Fork

BTW, I believe most of the No-peds used 16" wheels.