Recumbent - EZ Sport 24" Front Wheel

EZ Sport 24" Front Wheel
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I've had my EZ Sport since 2003 and have always loved riding it.
The only complaint I ever had was with the twitchiness and rough riding of the small front wheel.
I hadn't kept up with the latest recumbent models for several years now.
A few months ago I decided to search online to see if they still make and sell the EZ Sport.
In my search I ran across the Rans XP , the Lightfoot Ranger, and the Cycle Genius Falcon all which had a larger front wheel.
At first, I thought about buying one of these new style recumbents.
This thought progressed to the idea of upgrading my EZ Sport to a larger front wheel instead.
I searched the internet for feedback from other EZ Sport owners who had already done this.
I only found one picture of an EZ Sport with a 26" motorized front wheel, but no feedback on handling.
And from the picture it looked like a strong possibility of pedal/toe interference.
So, I took some accurate measurements of the frame, fork and wheel and put them in my CAD program.
This allowed me to play with different size wheels and forks to see how they would fit.
I found that with a 26" fork and a 24" wheel I would get the same pedal/toe clearance as the original 20" fork/tire setup.
However, either a 26" fork and 26" wheel or a 24" fork and 24" wheel would have probably fit, but would have been very close to having pedal/toe interference.
I also read up on bike geometry and how this modification would affect the bike's handling.
I found from my CAD program that the 24" trail would increase about 36% from about 72mm to about 98mm.
From what I read, this larger trail would increase the bike's straight line stability, but also might increase wheel flop.
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So, I decided to give it a try in steps.
My first step was to find a 26" fork and try it with my 20" wheel and see how it handled.
I was pleasantly surprised.
I liked how the bottom bracket was raised up a couple of inches and the seat bottom tilted back a couple of degrees.
The handling and stability felt better.
I guess the change in headtube angle giving an increase in trail maybe account for this.
It was a better riding position for me.
I rode this way for about a month while I looked at wheel options.
I debated whether to try 26" or 24" wheel first.
Certainly, 26" wheels have better tire selection.
And I could use the V-brake posts on the fork.
So, it would be an easier modification.
However, to me the 24" wheel fit better on the EZ Sport as far as pedal/toe clearance.
But, this would mean I would have to go with another brake system, because the V-brake posts wouldn't be aligned.
Even so, my gut told me to go with the 24" wheel.
Also, I went with a 507 rim instead of a 520 because I like slightly wider tires rather than skinny road tires.
And the Schwalbe Marathon 24 x 1.75 was available for the 507.
This is the tire I would eventually like to upgrade to on both the front and rear.
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Brake Modifications:
I carefully cut off the V-brake posts and filed the fork tubes smooth.
I installed a 3/4" metal pipe into the fork steerer tube to provide the down drop for the calliper brake.
I installed 1/2" x 5" x 3/8" metal bar to bridge between the two fork tubes to give added stabilization for the brake.
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So, what I ended up with was the following parts.
ATB Hybrid Black 1" Steel 26" Fork $12.95
WTB Dual Duty FR Alloy 24 X 1.75 36H Front Wheel (507) $17.74
Slime Smart Tube Schrader Valve Bicycle Tube (24 x 1.75-2.125) $5.93
Kenda K52 Street BMX Tire 24 x 1.75 $9.19
Planet Bike 7018 Front Fender (26-inches /50-mm width) $13.30
Odyssey 1999 Sidepull Caliper Brake $8.82
So, for $67.93 plus shipping I got a recumbent with a larger front wheel.
Quite a contrast to the $1500 I was tempted to spend on a new Cycle Genius Dual 26"
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Conclusion:
I am a very happy camper.
I love the way my EZ Sport handles with this 24" wheel.
Both the low speed and high speed handling are much more stable.
The ride over rough road spots is much smoother.
Turning sharp corners is a lot easier and smoother.
The seat bottom tilt back and bottom bracket elevation is more comfortable for me.
As far as increased wheel flop, I really don't know.
I certainly haven't experienced anything while riding that I could describe as wheel flop.
I only wish I would have done this wheel change years ago.
And the more that I ride with this wheel size, the more I like it.
For me, the 24" wheel really makes the EZ Sport more comfortable and more stable to ride.
In fact, I am so happy with my EZ Sport wheel change that I decided that I wanted to share my experience with other EZ Sport riders.

It wasn't the small front wheel that was the source of your problems, it was lack of trail. What you accomplished with that change was to give yourself more trail. And yes, I'd expect the result you got. It's good to hear it worked out for you.

What's "trail". bk

Trail is the distance between the head tube center line extended to the ground and where the tire contacts the ground.
Almost all bicycle wheels contact the ground behind where the extended steering axis centerline intersects the ground.
The distance varies among bicycles from 1/2 inch to about 6 inches.
The more trail the more stable the straight line riding.
However, heavy steering and wheel flop can result with too much trail.
If you google "bicycle geometry" there are lots of articles on trail.

I also have a homebuilt CLWB with a 26" rear wheel and a 24" front wheel. In January, I discovered it was supposed to be built with a 20" front wheel. I had just used a 24" because that's what I had. So I figured replacing it with a 20" front wheel. However, I since changed my mind, and decide to keep the 24" wheel simply because it will give a smoother ride over potholees. The only good replacing it with a a smaller front wheel would be moving the weight distribution closer to 50/50. Right now, the weight distribution is 37%F, 63%R. I have had no real handling problems with the bike, other than faulty components that I eventually replaced. So, I'm happy to hear about your experience with the EZ Sport, even though I don't have an EZ Sport. I'll measure the trail when I get a chance.

I measured my trail at 4.1875in (+- 1/8) which is 106mm (+-3). I extended the line from the center of the top of the fork stem through the center of the bottom of the fork stem to the pavement. I think that's the way it's supposed to be measured.

Yes, extend the axis of the head/steerer tube all the way to the ground, then measure back to the point directly below the front axle. BTW, 37/63 sounds pretty good to me for a LWB.

37/63 sounds pretty good to me for a LWB.50/50 is even better - unfortunately, overall length then becomes a problem.

Contrary to popular belief, adding a larger diameter front wheel to an LWB makes low speed balancing and maneuverability more difficult, not less. The same conditions also applies to rear biased weight distribution, excessive trail and tiller.

"Twitchiness" is a rarely used word among LWB owners. The few who do express it, either haven't learned how to relax at the controls, ridden the likes of a RANS Rocket, V-Rex or similar SWB platform in which to draw an accurate comparison, or have not installed the correct tires and/or used the recommended inflation pressure. There is many excellent tires available to fine-tune handling, without resorting to extensive and expensive geometry altering modifications.

Contrary to popular belief, adding a larger diameter front wheel to an LWB makes low speed balancing and maneuverability more difficult, not less. The same conditions also applies to rear biased weight distribution, excessive trail and tiller.

"Twitchiness" is a rarely used word among LWB owners. The few who do express it, either haven't learned how to relax at the controls, ridden the likes of a RANS Rocket, V-Rex or similar SWB platform in which to draw an accurate comparison, or have not installed the correct tires and/or used the recommended inflation pressure. There is many excellent tires available to fine-tune handling, without resorting to extensive and expensive geometry altering modifications.
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For me, this was all an experiment.
When I talked to one LBS about doing this he told me I was crazy to mess with my bike geometry.
That's when I started reading as much as I could about bike geometry as I could before I undertook this endeavor.
And my basic rule was to make sure I could go back to the original 20" setup if I didn't like the 24" wheel.
I really didn't know how this would work out.
And boy was I pleasantly surprised.
And the more I ride with the larger wheel, the more I love it.
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By twitchiness I mean when going at slow speed there is a tendency to constantly move the handlebars back and forth.
Yes, you are right that relaxing can help reduce the twitchiness but it's still there.
It's not like I haven't gotten used to my bike, because I've ridden it for 5-6 years.
I had the same problem with my Burley LImbo SWB configured which I had before the EZ Sport.
So I know what a SWB feels like.
And my tires are the Kenda Kwest at 100 psi.
That being said, I found that with the 24" wheel there is very little, if any, twitchiness as I described it.
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In addition, the high speed handling is much more stable.
I've actually been able to ride no-hands a few times just to see if it was possible.
Certainly, not as easy as an upright, but with the 20" wheel I couldn't even attempt no-hands.
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And turning is much smoother.
With the 20" wheel, I always felt like half way into the sharp turn like a u-turn, that the bike wanted to fall over on me.
With the 24" wheel, I'm amazed at how smooth and stable the turns are.
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And rough roads are smoother now.
I'm sure the lower pressure tire is part of it.
But, it's my opinion that the larger wheel rides over the bumps better.
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All in all, I'm one happy camper with this 24" wheel.

Papa, yeah maybe a 20inch wheel would improve climbing. (I know it would improve aerodynamics.) But I think maybe a new chainwheel might be a better first investment. My two existing chainrings are 40 tooth and 52 tooth. So, in the smallest gear, the diameter ratio of the 40-tooth chainring to the largest cog is 171mm/114mm or 1.5. Too big for climbing hills.

By twitchiness I mean when going at slow speed there is a tendency to constantly move the handlebars back and forth.What you just described (quite accurately, I might add), is a very real and necessary input requirement to sustain a vertical position on single-track-vehicles. Nearly all single-track-vehicles, (including LWB recumbents), are balanced by laterally repositioning the front tire's contact patch beneath the vehicle's center of mass (CoM). We do this by repeatedly turning the handle bars to the left and right - much like balancing a vertically positioned broom in the palm of one's hand. Most riders don't notice it because its usually learned at a very young age and retained subconsciously. But apparently you do notice it, and view it as some strange abnormality or design flaw. And why you apparently tolerated it for 5-6 years then suddenly decided to make major changes, is beyond me. My guess is that after scanning the current 'big wheel fad' 'bents, you just decided to join the crowd - and save a few bucks in the process.

I don't mean to burst your bubble, but when you install a significantly larger diameter front wheel on an LWB recumbent, you also altered the ability to balance the vehicle in a negative way - especially at low speeds. This happens because you not only increase the mass along the steering axis, but you also increased the force necessary to turn the handle bars by lengthening the size of the front tire's contact patch. The larger front wheel also moves the CoM rearward. This means that steering inputs must be increased and initiated more abruptly. Not usually a problem at higher speeds, due to the increase in forward velocity, but at lower speeds, it forces the rider to magnify steering inputs to maintain balance. You obviously think that the changes you made somehow magically improved low speed handling, but I can assure you that the laws of physics dictates otherwise.

I don't mean to burst your bubble, but when you install a significantly larger diameter front wheel on an LWB recumbent, you also altered the ability to balance the vehicle in a negative way - especially at low speeds. This happens because you not only increase the mass along the steering axis, but you also increased the force necessary to turn the handle bars by lengthening the size of the front tire's contact patch. The larger front wheel also moves the CoM rearward. This means that steering inputs must be increased and initiated more abruptly. Not usually a problem at higher speeds, due to the increase in forward velocity, but at lower speeds, it forces the rider to magnify steering inputs to maintain balance. You obviously think that the changes you made somehow magically improved low speed handling, but I can assure that the laws of physics dictates otherwise.

PaPa,
I've read your post several times and don't quite understand fully what you are saying.
I just came back from an hour+ ride up and down hilly roads where at times I'm using the lowest gearing.
And I thought about what had been previously said about low speed handling.
As far as the correct physics theories go, I have no idea.
But I did pay attention to how the slow speed handling was on my ride.
All I know is that the low speed straight line riding is more stable and the slow speed turning is smoother and easier with this 24" wheel.

iconoclast,

Please excuse the OT, but what's the significance behind your chosen moniker? iconoclast (http://www.google.com/search?hl=en&client=opera&rls=en&defl=en&q=define:iconoclast&ei=QYaxSe22E4KEsAODhdF-&sa=X&oi=glossary_definition&ct=title),

From Wikipedia, the free encyclopedia
An iconoclast is someone who performs iconoclasm — destruction of religious symbols, or, by extension, established dogma or conventions.
It was a nickname given to me by a lady friend years ago because I liked to question everything especially established truths that you are not allowed to question.

Hi,

I've been riding my EZ Sport CX since 2004. I've upgraded everything but the frame, seat, headset, and handlebars. I've never had problems with twitchiness. I can take my hands off the bars and it coast straight on. At intersections, I'll slow to almost a stop before I have to place my feet down.

List of changes to my EZ Sport CX
• Shimano LX M570 Brake Lever/Shifter 9 spd (known as Mega 9).
• Shimano LX M570 V-Brake, Cool Stop pads
• Shimano LX M570 Rear Derailleur.
• Shimano LX M570 Front Derailleur.
• Shimano HG50 (105) 9spd Cassette 12-28, modified (12,13,14,15,17,19,21,23, 28)
• Shimano HG73 chain.
• Truvativ ISOflow Crank, modified to140mm, 44-32-22
• Shimano LX UN-73 BB 68x113mm
• Ritchety Logic WCS XC Rear Wheel (2006 model)
• Shimano XT Hub and Alex Rims DA16
• Schwable Marathon 20 X 1.50 and 26 X 1.50
• Windwarp fairing
• Speedplay Frogs Pedals

All the best!

Angelo

You probably could have borrowed a 26" front wheel from someone and slapped it on your bike to check for clearance.

Congrats on some good thinking and nice results. Don't let the detractors bother you.

I can take my hands off the bars and it coast straight on.
Angelo

Perhaps, they changed the EZ Sport geometry after my LE model.
I know they changed the headset size.
All I know is I could never have ridden no hands on my original EZ Sport LE.

Congrats on some good thinking and nice results. Don't let the detractors bother you.

I must admit I've been surprised about all the negativity.
Sometimes when I'm riding and appreciating how well my EZ Sport handles, I have to chuckle over the responses this forum has given my post.
That's okay.
I've ridden many many miles since I've made the change to the 24" wheel and I couldn't be happier with how it's improved the handling.
I'm a happy camper.
That's all that matters.
Thanks for the positive post.

For crank clearance you can always op for shorter length crank. Checkout http://bikesmithdesign.com/Short_Cranks/index.html

Mark is a great guy, his work is top-notch!

For crank clearance you can always op for shorter length crank. Checkout http://bikesmithdesign.com/Short_Cranks/index.html

Mark is a great guy, his work is top-notch!

Yes, this is true.
Also, I could bend the forks with a tube bender and give more fork offset.
This is probably what I'll do to spare fork, if I decide to try the 26" wheel in the future.
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Crank length is another one of those debates where people have arguments for both sides.
When I decided to change my crankset from 52-42-30 to 44-32-22 I read a lot of posts here and there about crank length.
Funny thing, I decided to go from 170mm to 175mm despite all the talk about the merits of shorter crank lengths.
I guess that's why I have the nickname Iconoclast.
And to tell you the truth, I don't think I can notice the difference between 170mm and 175mm.
But, I'm glad I had the extra clearance that allowed me to use the 175mm.

I must admit I've been surprised about all the negativity."Surprised about all the negatively" huh? Well, you can start by doing a RANS V2 search on BROL - a proven 20/26 sweet handling LWB design, which was later offered with a 26" front wheel and dubbed the "V26" - and when shod with Big Apples, as one user reported, "handled like a semi".

You are not the only 'armchair' designer who suffers from the placebo effect.