Interesting front suspension setup...

So, I like different. I seen this model model Ural at a bike night. It fist caught my attention because it was fitted as a military servicar. Theres lots to look at in person. It also has an optional 2wd option to engage the sidecar wheel.

Anyway, check out the front suspension. With some practical planning and engineering, it looks fairly straight forward. Now, I have got to assume that it won't be as nice as standard forks but I Really like the look of it. Plus, very little upkeep!

A few points:

The red arrow is directed at the down tube, just below the bottom triple. If you look carefully, you can see there is a slight bend here. I would imagine that this is to keep the shock in a more upright orientation so as to not lose any motion of the shock. Also since the impact on the shock will not slide back on the down tubes, this bend may be to prevent a bend from heavy impact.

The yellow arrow points out what I will call the "stabilizer". This unit is actually one piece that wraps around the back of the tire. Of course, this is the piece that allows the shock to flex. However, I believe that it also serves to stabilize the wheel and ensure that both shocks work together. Since both shock are separate entities, they would allow the tire to flex off center if it both sides of the axle were not joined at some point.



Check it out, give me your thoughts. IDK with the right shocks maybe it could be a decent set up. I feel like the angle of rake could be played with also if the length of the down tube is altered accordingly.

 

For some reason, i cant help but think that would be a little but rougher of a ride. Im no engineer though, or even an experienced rider, lol. Definately an interesting concept, im sure theres a good reason you dont see that setup anymore though.

 

Don't know the technical name for that type of suspension but the design practicly eliminates front end dive while braking. as braking is applied it will pivot the lower arm raising the front syspension. Someday would like to ride a bike with that setup.

 

That's Ural's version of what's called an Earle's Fork, and they were a feature of the early ('55~'69) BMWs. It's also a relatively common "retrofit" for a bike that will be dedicated to sidecar use.

A buddy of mine has an old BMW, a '66 I believe, with one and it takes some getting used to the complete lack of front end dive no matter how hard you brake. Ride-wise, it's fine; the steering is a bit "truck-like" because of all the mass you're slinging about down there.

 

I have had 'leading link forks' on two of my bikes and sidecars (but not the Venture). The suspension is much better over bumpy ground than telescopic forks and there is far less flex. When you design/set up the front end you can reduce the trail which makes for much easier steering too.

A downside that I have found is that any 'wobble' on the handlebars is accentuated as there is much more weight at a distance from the steering axis than you would have with teslescopic forks - at least that's how I explain it to myself. This is easily resolved with a steering damper though.

A lot of people use a different front wheel so they can use a car tyre on the front as well.

Generally they are really common in the UK and the rest of Europe and there are a number of companies who make them, although as was said above, you could make up a set yourself - just make sure that you use pretty substantial material for the fork legs.

 

http://www.youtube.com/watch?v=dN5PAwc1ns8

At about the 2:40 mark you get some good riding scenes.....

Ural bought out the old BMW tooling a while back, thus the very teutonic looks.

He should mount a 50-caliber machine gun on the sidecar deck, it would look just like it came out of the movie The Great Escape.

 

After watching that video, I don't know what to think. Those guys are really working those things through the woods and hills, not to mention how they are launching them off those ramps. I don't think a standard set of XJ forks could handle that abuse, not without bottoming out anyhow.

I'm thinking I may have to start making some plans. It would certainly make running a wider front tire a lot easier, maybe like a 110/120 so it still pulls in the corners.

 

History of the Ural. Back at the beginning years of WW2 (40-41) when Germany and the USSR were at peace, Germany sold some BMW (Bavarian Motor Works) motorcycles to the USSR. The Russians liked the bike and didn't have a motorcycle design for their military at the time. The Russians copied the design and the Ural was born. The name actually comes from where the motorcycle was manufactured, The Ural mountains. Not much has changed in the design over the years.
The front suspension was BMW's version of a springer front end and hasn't changed much either.