Oversize front wheel?

[Plazebo]

Hi,

Has anyone tried putting an oversize un-suspended fork and wheel on a frame that used to have front suspension?

EG:
24" wheel on a 20" folding bike OR
26" wheel on a 24" kids mtb

I figure the frame orientation would be maintained if the original shocks had 2" travel. And there would be more rubber on the road for traction.

Cheers,
Pete

 

[Charles.Plager]

Hi Pete,
The amount of rubber

Hi Pete,

The amount of rubber on the road ( i.e., contact patch size) is completely determined by the amount of weight on the tire and the air pressure (area = weight / pressure). I recommend riding with wide slicks so that if you need to, you can lower the pressure in the tire to increase the contact patch size.

If you keep the angle of the bike the same by swapping out forks, then I don't really see any harm in doing this besides it looking funny . (You'll need to carry two different size spare tubes, but that's common for a lot of long wheel base recumbents). The only advantage of the larger drive wheel in my opinion would be to get higher gearing.

Cheers,
Charles

p.s. Going to a 24" wheel with appropriate fork is going to be 4" different than the 20" wheel and I think you'll find that the bike will be tilted back (maybe too much). 26" to 24" is only a 2" difference and with the right fork, this might not change the angle too much. This is all speculation on my part, so take it for what you want.

 

[John Tolhurst]

Funnily enough, increasing

Funnily enough, increasing the contact path doesn't increase traction, but it does prevent loss of road contact, and that does aid consistent traction, which of course is rather important when shove comes to slip. You can explore this in the equasions around traction and it is indeed true.

Its a valid suggestion, if the axle is in the same place, what does the wheel care if there is a sold structure or suspension structure above it?

 

[Charles.Plager]

John wrote:
Its a valid

John wrote:

Its a valid suggestion, if the axle is in the same place, what does the wheel care if there is a sold structure or suspension structure above it?

I'll point out that on rough roads, a wise man* once said that suspension helps the wheel stay on the road.

Cheers, Charles

* O.k., it was you, John.

 

[floridabike]

Un-suspended Fork

I started with the Conversion kit and the V2/K frameset and a fork with suspension. I later modified a fork without suspension and eliminated the triangle pieces and having to reverse the fork and saved considerable weight. The fork is setup to accept both 700C and 26" wheels. I switch between 1.75" and 2.25" tires on the 26" wheels, depending where I ride. Most of my riding is done with the 1.75" on the 26" wheels and seems to accommodate both street and some trail riding. Just having the rear suspension seems to be adequate for my rides. I have tried the 700C wheel in the front with the 26" wheel in the rear, just for fun.

 

[Charles.Plager]

Hi FB,
Very interesting.
Can

Hi FB,

Very interesting.

Can you post a close-up picture of how the triangle attaches to the fork?

How did you get the fork wide enough to allow the drive wheel?

And what's your opinion of with versus without front suspension?

Cheers,
Charles

 

[floridabike]

Fork Triangles

The triangle plates come with the kit and instructions on mounting them to the fork.

I didn't like the looks or the weight so I modified a CrMo steel fork designed for 700C wheels. Using a torch to heat and spread the legs near the top and then applied heat about a third of the way down and closed them to match the width of the axle. I then brazed the tabs on to attach the front arms, tabs for the 26" brakes, and the hanger for the derailleur. By using the conversion kit and the V2/K frameset and the Free rider handlebar kit I have a Cruzbike Freerider. Did I save any money ? probably not but I've had lots of fun and this is a great bike, not only for riding but for anyone that likes to experiment.

I'm sure there is a great engineering explanation but if you are riding on a rough worn textured surface or hit a sharp edge like riding on a sidewalk, suspension doesn't do much, especially the front. I found that going to a wider tire was more effective in absorbing this type of surface. If I were to ride more on rough trails, I would prefer the front suspension.

It would be nice if Cruzbike sold the Sofrider fork, with or without the suspension.

 

[Charles.Plager]

Hi FB,
I know how the

Hi FB,

I know how the conversion kit attaches, I'm hoping to see how you attached the triangle to your new fork.

I agree that front suspension doesn't do much for sidewalk-sized bumps. I find that it helps on rougher roads to take the edge off.

Thanks,
Charles

 

[Doug Burton]

26" wheels in 24" frames

I've done this with every Tiara frame I've used. (Tiara's are all 24" (ISO 507) bikes).

One of John's early conversions for his wife was done this way, and that was an excellent bike.

If you can adapt the rear brake mounts or use an alternate rear brake, it works very well and results in a small frame with good tire choices in the 26" range. There are many ways to get the rear brakes right.

650C forks and wheels can also work (but the tire choices are very limited)

 

[floridabike]

Fork Triangles

Hi Charles,

I eliminated the fork triangles by spreading the fork and brazing the tabs on for the front arms and the fork doesn't have to be turned around. Here's a better picture. Looks something like the Sofrider fork but I have the advantage with brake tabs for both 26" and 700c wheels. I may add the disk brakes but this works for now.

Phil

 

[Charles.Plager]

Hi Phil,
That fork looks

Hi Phil,

That fork looks fantastic. It looks both lighter and much cleaner than the conversion kit. Ready to take orders?

Cheers,
Charles

 

[Plazebo]

A flawed idea?

I've reached the conclusion that an oversize front wheel is flawed because there are easier ways to achieve the same effect. Specifically, the main advantage would be to get a lower center-of-gravity without sacrificing front wheel size. Which can be achieved with frame design.

So for better ride characteristics I need a proper V2/K frame. And given that I'm time and budget oriented (and not a tinkerer) I am now seriously considering a Sofrider, which will be a much better ride than I could ever come up with using a conversion kit.

It was definitely a fun thought experiment though.

Cheers,
Pete

PS: Excuse me while I go get some exercise and try to justify buying a Sofrider