Anyone ever tried this?

[Wildcat]

As I was riding through some sand the other day, this idea came to me. I wanted to keep going through soft sand instead of bogging down. A pair of 2.125 beach cruiser type tires together would give 4.25 inches of width, like a fat tire cruiser. The total weight of bike and rider would be spread over 3 points instead of two. The idea is to mount the wheels on the forks and make a brace to go around to support the other side of each axle. The brace would be mounted or welded to the forks. I would think this has been tried already but couldn't find any pics.

 

[LukeTheJoker]

Turning may be an issue...

Luke.

 

[horsefarmer]

As I was riding through some sand the other day, this idea came to me. I wanted to keep going through soft sand instead of bogging down. A pair of 2.125 beach cruiser type tires together would give 4.25 inches of width, like a fat tire cruiser. The total weight of bike and rider would be spread over 3 points instead of two. The idea is to mount the wheels on the forks and make a brace to go around to support the other side of each axle. The brace would be mounted or welded to the forks. I would think this has been tried already but couldn't find any pics.

View attachment 17744

Build a prototype and keep us informed! I think the idea is to get the tire contact patch bigger to reduce psi on the surface. I have observed my Dually truck rear wheels have more flotation in sand and soft ground than the fronts.

 

[Wildcat]

One thing I thought of that might be a problem is the balancing when going from trike configuration to bike 2 wheel. You balance just the opposite when on 3 or more wheels than on 2, so as one front wheel comes off the ground in a turn, it may cause some confusion. I'll visit the junk guy down at the old market and see what I can come up with. Maybe a 4 wheel build, the 2 wheels up front side by side, and the rear wheels one after the other. It may just work out for the annual build off. I'll just get parts together then try to get it to work later.

 

[CrazyDave]

I am function before form kinda guy, so bear with me. I think it would be infinitely easier to swap out to a fork that would hold one 4" tire. As stated, turning that thing in the deep sand, you better have strong bars or they may bend! If you do this, do the same to the back and run a chain to the front wheel, then it will be the first 4x4 bicycle i ever seen hehehe.

 

[The Renaissance Man]

You might have better steering if you angle the front wheels in at the bottom side by side making a V like on farm tractors. Still not sure if it would be rideable though.

 

[Duchess]

You have more weight on the rear, so that's where it would be of more benefit.

But, if you mean a trike, you could use a threaded fork locked into a straight position. The wheels would mount to a strong stationary axle of your chosen length, probably with buttresses running from near the wheel ends to the upper part of the fork blades for strength. The wheels would be mounted to the axle in a kingpin setup with trailing arms that would couple via small ball joint to steering rods that go to a central steering shaft that would go back up through the fork and attach to the handlebar. Come to think of it, you might be better off using the headset bearings for this central shaft with a modified legless fork and mounting the wheel-end axle buttresses solidly to the headtube itself. I hope that makes sense—I have a head cold and I'm not sure my communication skills are all that great right now.

 

[Wildcat]

I am function before form kinda guy, so bear with me. I think it would be infinitely easier to swap out to a fork that would hold one 4" tire. As stated, turning that thing in the deep sand, you better have strong bars or they may bend! If you do this, do the same to the back and run a chain to the front wheel, then it will be the first 4x4 bicycle i ever seen hehehe.

Someone in Minnesota came up with a bike a few years back using a cable from the cranks to a worm gear on the front wheel making it all wheel drive.

 

[Wildcat]

You might have better steering if you angle the front wheels in at the bottom side by side making a V like on farm tractors. Still not sure if it would be rideable though.

I'll have to do a prototype to see how it handles. An angle would be possible by a slight bend on the fork blades and axle slots on the brace that allow for adjustment. I always wondered why tractors wheels are at an angle.

 

[The Renaissance Man]

I always wondered why tractors wheels are at an angle.

It think it had more to do with keeping the wheels between the crop rows than anything and it also kept mud from packing between the wheels, but I'm no farmer. However, I did stay at a Holiday Inn Express.

But in your case, it would keep the contact patch closer together and (possibly) help lessen the problem with leaning the bike to steer.

 

[kingfish254]

@gsc tried something sorta along those lines a couple of build offs ago.

 

[Wildcat]

You have more weight on the rear, so that's where it would be of more benefit.

But, if you mean a trike, you could use a threaded fork locked into a straight position. The wheels would mount to a strong stationary axle of your chosen length, probably with buttresses running from near the wheel ends to the upper part of the fork blades for strength. The wheels would be mounted to the axle in a kingpin setup with trailing arms that would couple via small ball joint to steering rods that go to a central steering shaft that would go back up through the fork and attach to the handlebar. Come to think of it, you might be better off using the headset bearings for this central shaft with a modified legless fork and mounting the wheel-end axle buttresses solidly to the headtube itself. I hope that makes sense—I have a head cold and I'm not sure my communication skills are all that great right now.

I've seen a lot of those I think, but it's the extra weight and engineering that I'm trying to avoid. Is this what you were explaining?

 

[Wildcat]

I found a couple of pics similar to the configuration, so I'm a little more hopeful it will work.

 

[Wildcat]

@gsc tried something sorta along those lines a couple of build offs ago.

On his, it steered a little different, but he didn't like the looks of the bike with it.
"So.... after looking at it a long time and doing a rolling test drive, it steered ok , you would just pivot from wheel to wheel to steer and it was heavy when in the turn, while I may have to deviate from my original vision , I decided to scrap the twin wheel set up, plus I wasn't happy with the way the bike flowed ,too stubby in front"

 

[Duchess]

I've seen a lot of those I think, but it's the extra weight and engineering that I'm trying to avoid. Is this what you were explaining?

That looks exactly like it. They stole my idea out of my head and went back in time! I hate it when they do that. There really are no new ideas in bikes.

I designed a narrow track like the other style, too, but I designed it to lean kind of like that Piaggio MP3 or whatever, but different mechanicals. It looked like it was going to be too heavy, too expensive, and of limited advantage, so I never built it. But I still like the idea of the extra wheel. Interested to see what you come up with.

 

[gsc]

I still have the wheels in the pile...lmk,....cheap.

 

[Wildcat]

I still have the wheels in the pile...lmk,....cheap.

But I'm in the Philippines, halfway around the world. Thanks though.

I'm thinking as one wheel is off the ground, the wheel doing the work will be getting a lot of stress.

 

[Wildcat]

I checked it out and see how the angle must be different because one wheel is following a different (longer) path from the other. The inside wheel is following a tighter circle. That makes sense.

However, I'm guessing the tread width of both wheels together as being about 10 inches total, which would be the same as having one very wide front tire. When turning, the tread of the two tires will be in the same spot as the portion of tread of the 10 inch tire.

I'm studying and taking pre-finals right now, but this weekend is free to go to the old market to see what they have in wheels and tires, so I can give it a try on one of my existing bikes, or maybe they have enough junk for a prototype.

 

[Duchess]

The inside tire will just scrub a little. The narrower track will reduce the scrub vs. a wider track, but will also worsen the effect of it. How much of a problem this could be depends on your traction and cg (and how you alter it as you ride).

 

[CrazyDave]

If the purpose of this design is to go through soft sand better, I am not sure a extra wheel is going to help. All the designs I am aware of involving more than 2 wheels is for added stability or carrying capacity. The extra weight and drag of this extra wheel I suspect will hinder more than promote better sand manners on your peddled machine, however it may be extra cool and unique! Just my 2 cents.