The Zevo Recumbent Bike

Somewhat recently I posted about the ideas behind the semi-novel steering geometry of the Zevo.  But what about the rest of the bike?  What’s it like, in a general sense, to ride this thing?

Before I go further, I should note that I was holding off on finishing this up because till recently I had been using the bike with a temporary fork, and although the two critical dimensions of the temporary fork (axle-to-crown and offset/rake) were quite close to the final, intended design, they weren’t exactly the same, either.  With the new fork now fitted and some miles have passed underneath me since, I feel like I can properly comment on the handling.   I’m also gonna take the time to discuss the design as a whole, because there is more to a bike than how it handles (although that’s pretty damn important, in my opinion).

Before I started down the path of designing a bike, I had articulated the following list of wants and needs in a recumbent bike:

1. Body angle of about 140 deg. with 25 deg. seat:  This is an entirely personal thing, as it’s the position I have gravitated towards over the years as what works best for me, while maintaining a good balance between aerodynamics, power delivery, and comfort.  I worked out that this would require a BB height above the seat of about 9.0 inches or so.  For someone who does a lot of climbing, it’s harder to tolerate quite as low of a seat angle. I spent some time years ago running about 18-19 degrees and while it worked well on the flat and gentle uphills, it didn’t feel good on steep climbs. I felt it also reduced my ability to see traffic, road conditions, etc. For me a good compromise is about 25 degrees. 

2.  Seat height no higher than 23 inches:  Somewhat similar to considerations of seat angle, being able to see and be seen is affected by the height of the seat.  Having ridden both mid- and high-racers in the past, as well as several different very low trikes, I have come to the general conclusion that I feel more confident in traffic situations and other less than perfect scenarios being reasonably high up.  The limiter being a seat low enough to make starts and stops easy by making them flat-footed, not tippy-toe affairs.

3. Low flop steering geometry for excellent low speed handling:  You’ve read enough about that already here:  https://rothrockcyrcle.wordpress.com/2020/09/26/steering-geometry-of-short-wheelbase-recumbent-bikes/  

4. Clearance for 2″ wide 650B or 32mm-700c with fenders, front and rear:  I wanted the versatility of an efficient road going setup, as well as one well suited to gravel / mixed-surface riding.  I have always been most interested in versatile bikes, and the Zevo is not meant to be a specialized, single-use machine.

5. Made of steel or titanium, and very durable and suitable for gravel roads and general abuse:  I don’t want to baby this thing.  If I feel like riding on Rothrock rocks, I’m gonna do it.  If I design this thing right, I’ll want to ride it for a couple decades.  It’s gotta last.

6. Stiff under hard pedaling / climbing:  I find this to be the most important issue for good climbing on a recumbent.  So many recumbent bikes and trikes flex like big bows under chain tension, and you can feel this mush in the pedals.  In my experience this does nothing good for a recumbent’s ability to climb.  I was hoping to achieve stiffness through a combination of three things. First, I didn’t skimp on material usage.  I used wall thicknesses almost double what typically is used in 2″ diameter steel stick bents, for example. I used 1.55 mm thick tubing for the three main tubes instead a more common 0.9mm. This almost accounts for the reduced modulus of elasticity of Ti compared to steel.  Second, I aligned the powerside chain line as close to the main tubes as possible. The angle between them doesn’t exceed 10 deg. or so. This required a second power side idler, but I used high quality oversized toothed idlers and mounted them in a very rigid way to the main tubes. This, of course, minimizes the bending moment on the tubes.  Lastly, I triangulated as much as I could, and at the location of the powerside idlers, so the reaction forces at the idler bolts would produce the least bending.  Another nice effect is that the direction of force during the fat part of the power stroke has the first segment of powerside chain almost exactly in opposition. An FEA model would be a nice thing to do to back up my seat of the pants engineering, but I don’t have access to the software or the expertise to use it. I need to find a college student who needs a project.  Some folks will howl about the extra power side idler saying it sucks up power.  Obviously, I am not so sure about that.  Unscientifically I will note that my Windcheetah has two power side idlers and doesn’t have a lot of drivetrain drag, and climbs very well, partly I think because the power side chain follows the main tube very closely.  Velomo also has a double idler bike (Hi-Fly). I am encouraged that I am not the only arrogant dolt trying this.

7. Ability to take a 50T rear cog:  This also has its roots in wanting to climb well.  But it’s not just about getting a low gear, but by getting a low gear using a reasonable large chainring.  The smaller the chainring, the higher the chain tension.  The higher the chain tension, the greater the frame flex.  I also thought it might be nice to have a bike with a single or, at most, double chainring.  A monster cassette makes that practical.

8. Rear Wheel Drive and Weight Distribution of about 55% rear and 45% front:  I feel this produces the best handling, and this is especially important for non-pavement use.  Both wheels need good weight distribution, and when going up steep hills that may not be paved, or may not be clean and dry, demands RWD.

9. Braze-ons where I want them:  It’s a custom bike.  Why not?

10. All external cable routing for ease of maintenance:  As you can probably tell, I am a pragmatist.  I like the looks of a sleek racy bike with hidden cables, but I don’t really want to live with one of those.

11. Clearance to the rear wheel for a seat bag:  Some dual 700C bikes with reasonably low-elevation, laid back seats can’t take my favorite form of baggage due to conflict with the rear tire.   This wasn’t a deal breaker, but I really wanted to try to sneak this one in if possible.

12. A “Future proof” rear dropout system:  Industry standards, especially for disc brake bikes, are in flux.  I wanted a dropout that could be converted from the QR wheels I currently use to 12mm 142mm TA, or perhaps some future standard that hasn’t been pushed on consumers yet.  The finished bike ended up with Paragon sliding dropouts, as a result.  

You can name any number of commercial bikes that can hit half, 2/3rds, or even 3/4ths of these items. But not all. I also had the urge to just simply come up with my own thing. I had some ideas floating around in my head for quite a while.   So that’s when I decided to see if all of these could be satisfied in a single design.  In the end, I am happy to say the answer was ‘yes’, and became the Zevo.  Of course, if you have perused this blog, you see the types of rides I like to do.  Obviously, the design criteria was shaped by those.  This bike is for me, after all.  I could care less if anyone else wants a bike like this (although folks are more than welcome to emulate the aspects that appeal to them in their own design).

So how does the bike handle?  Initial riding impressions were very good. The bike felt weird for the first minute or two, but that sensation went away very quickly and I really liked how it felt. At very low speed you need to more deliberately steer it. The bike doesn’t flop into the turn at all, you need to guide it fully through the turn. At first I thought this aspect of the handling was odd, and the steering felt a little heavy to me, but that quickly faded and then it just simply felt calm. At 15 mph and higher it feels like a lot of other bikes but below that the handling and feel barely changes, unlike most other bikes which markedly change in their handling behavior the slower you go.  At high speed and in fast turns it’s incredibly solid and confidence inspiring.  In fact, I think it’s a little dangerous because it inspires a level of confidence that my actual skills can’t fully support.   I’ve got about 1,000 miles on the bike at this point, and these initial impressions have proved to be lasting.  The bike is just easy to ride.  It’s the first dual 700c bike I have ridden that didn’t feel clumsy or ponderous. I can claim, without exaggeration, that this is the best handling recumbent bike I’ve ever ridden. It’s just so stable that it makes balancing the bike a mindless task, even at walking speeds.

The bike is a very good overall performer, and is quite fast. I wish I had more hard data to share, but I just have been riding it and not worrying much about speed. I did track my rides for the first month, though. Data from then shows it to be a little faster on mixed terrain rides than the Wishbone RT, which was previously the fastest bike I’ve ever had. On my one benchmark route, I managed averages in the 18.1 to 18.7 mph range, where the RT on that route was typically 17.7 to 18.2 mph or so in the month prior to getting the Zevo rolling. So about 0.5 mph difference. That benchmark route has no major climbs but a bunch of shorter, very steep ones, with an overall climbing rate of about 64 ft/mile.

Regarding frame stiffness under hard pedaling, the bike feels extremely stiff and solid.  On steep climbs and during hard accelerations and the bike just simply goes.  No mush in the pedals at all.  I will say it’s very slightly shy of the rigidity of the Wishbone Classic, but that bike’s stiffness is otherworldly.  On the Zevo, I can see a little lateral movement of the boom when pushing very hard.  Doesn’t seem to be twisting or moving down at all – just side to side a little.  I think the flex is real because I can sight the BB and f. derailleur post against the head tube as I am held very still in the seat.  It isn’t enough to be felt in the pedals, so it doesn’t strike me as a bad thing.  I get the impression that might even add to a nice, springy feedback sensation I experience at certain cadences and power outputs when climbing. Speed-wise, it’s every bit the equal as the previous climbing Champ, the Reynolds Wishbone. The Zevo might have and edge. It’s too close to call. The Zevo is pretty clearly a bit better uphill than the P38, though.

That said, the bike better be stiff.  It’s not light.  I knew it would be a little chunky, as I very much wanted to err on the side of stiffness and strength. I am a firm believer that even a couple extra pounds that makes a frame stiffer will pay back more than the weight penalty will take away.  Now, I do think it’s possible to have a frame so stiff that the extra weight is simply wasted and offers no benefit. I am not sure if we are at that point here or not. Might be close, but not quite. I think I’d have to build a lighter version of it and see if the stiffness is compromised too much.   However, logically, even if I am carrying around 1 or 2 lbs of extra/unnecessary weight in the frame, it’s not going to slow me down much since it’s slightly less than 1% of the total system weight. Here is where I remind myself that I need to lose about 15 lbs.

I also need to remind myself that this is actually a prototype.  Even with some small flaws there and there, all of the major design goals were achieved, and I feel a big weight off my shoulders. I had risked so much time, effort, and money into this gamble. I knew it was possible it would turn out to be a dud. I have generated  a list of things that I would change, but they are all minor things so far.  I am a perfectionist which is both a blessing and a curse.  The probability of me personally commissioning another one anytime in the next 5 years is low.  V1.1 is up to someone else to finance.  If that’s you, I’d be happy to do the CAD work to revise the design to suit your slightly larger x-seam, weight/stiffness priority, seat height / BB height relative to the seat preference, and preferences related to braze ons or other features.  

I would be remiss if I finished this write up and I didn’t give some credit to the bikes of George Reynolds that partially inspired the Zevo.  George’s bikes are super stiff, climb amazingly well, and handle great.  The Zevo’s steering geometry took the design of the Reynolds Wishbone and extended it to a relative extreme. The steering angle on the Zevo being a good 6 degrees steeper, and with more negative rake.  Hats off, George.  You really were onto something with your designs.

Further Information:

For the insomniacs in your life, here are some videos of me on the Zevo:

If the inbedded links below don’t work, go here: https://youtube.com/user/SuperKettMan

Also, compare the beginning of this video of me on the Zevo… (which you’ve seen already)  https://youtu.be/age43S0kwD4   …to this video from 5 years ago of me on the same section of road on the Metabike:

The difference in handling is plain to see, actually.

Here is a BROL thread about the design evolution: http://www.bentrideronline.com/messageboard/showthread.php?t=149640

Here is a Google picture folder of the Zevo in various states of completion and environs:

https://photos.app.goo.gl/Y4J9THYjwF7Vt5RW7

And lastly, here is a video of me talking about the bike:

About rothrockcyrcle

I am an endurance cyclist always looking for new ways to maximize fun and minimize BS.
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4 Responses to The Zevo Recumbent Bike

  1. For some information about the amount of tiller, use of OC steering, and issues of pedal steer related to the design of the Zevo, see this: https://rothrockcyrcle.wordpress.com/2020/12/25/tiller-distance-effects-in-swb-recumbent-handling-and-design/

  2. Pingback: Steering Geometry of Short Wheelbase Recumbent Bikes | The Rothrock Cyrcle of Hell

  3. David Wills says:

    Glad to see this initial review up. I’ve been curious to see how the build would go. The climbing videos look more stable than any bent videos I’ve seen, and more stable than what my minds eye sees when I climb on a bent. Congratulations, and I wish you many happy miles.

    • Thank you David. I’m liking the bike more and more as I continue to tweak my setup.

      The next experiment to to try the bike with a 26″ front wheel, keeping 700c in the back.

      There might be a Zevo 1.1 on the horizon. Someone I know is thinking about it. We’ll make some snall adjustments in the design for that one.

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