Barracuda lowracer version 2 plans

Barracuda Low-Racer Design 2

By Warren Beauchamp

11/12/2002
I have been riding the Barracuda lowracer for a couple years now. It's quite fast, handles great, and is stable at 60MPH. The only thing I don't like about it is it's weight. It currently weighs 38lbs bare. Many of the training rides, organized rides and races that I am in are in hilly areas, and winching the bike up the hills is tough. I can't afford to lose any weight personally, so this means the only way to go faster up the hills without blood doping is with a lighter bike. Most of the hammer-heads I'm riding with are getting lighter bikes (and getting faster!), so to keep up with them, it's time to design the next iteration of the Barracuda low racer. 
As a couple people I ride with are now sporting the latest in light weight carbon fiber lowracer technology (RazzFazzen), I decided to design my own carbon fiber lowracer. I really like the ability to carve any shape you want in the foam I would use for a mold, so this bike is highly stylized. Due to a lack of time, I decided not to build this one, but here is a scale drawing. These pictures can be clicked on for a higher resolution image.
Heck, if you are going to spend the time to build the carbon fiber low-racer, you may as well build a splitter plate version. This concept, in combination with really good wheel fairings, helps to fair the wheels and componentry to keep the bike's aerodynamic profile as clean as possible.
After more consideration, I decided that I would have to build it, or have it built out of super thin steel or or another lightweight metal. Both thin steel and aluminum have known problems with fatigue cracking. The only other metal available is titanium, which does not have a fatiguing problem. Custom Titanium recumbent builder George Reynolds came to mind, as I was impressed by his lightweight titanium T-bone big wheel recumbent. I contacted George to see if he would be willing to build a Titanium lowracer frameset for me. He was.
After spending countless hours designing the bike around George's 2"x3" oval titanium frame tubes, and 1.5"x.75" rear stay tubes, I came up with the design to the left. The geometry is very similar to the existing Barracuda. The cantilevered rear stays will give the bike passive rear suspension. I'm hoping to keep this bike down to around 20lbs.
I'm building an offset front fork and matching offset front wheel to get maximum chain clearance without the need for a monoblade fork. The chain stay on the road fork's right side goes straight down from the crown, and the left side chain stay moves out farther to the left to compensate. This means that the front wheel has to be dished heavily to compensate. While the idea for this comes from the RazzFazz, I'll be building mine out of steel, using a road bike fork kit. 

This not-to-scale drawing represents of view of the fork from the front of the bike.

This fork in combination with a re-spoked Pantour suspension hub, should make a good lightweight low-racer friendly suspended front end.

 

12/13/02
After taking a look at my drawing, and realizing how long it would take to make a weld all those mitered tubes, George countered with another drawing using only 3 frame tubes rather than 5. 
While it wasn't what I had originally envisioned, the compromises were acceptable. I redrew it to minimize seat height. This latest design iteration will not fit into the 'Cuda fairing, but it will be a lighter weight non-faired vehicle, and allow the seat to be laid back more. That should translate to FASTER unfaired...
The front wheel is now all built up, and the fork is cut and modified to make it offset. I'll wait until I get the frameset to braze it up to enable frame attitude minor adjustments. 
1/20/03
I received the frame from George last week, it looks great. It has beautiful welds, and is LLL (low, light and long). I weighed the bare bike with all the bracketry George sent, and it's about 5 lbs. I weighed all the parts that I'm planning to put on the bike at about 13.5 lbs. I'm sure there will be more stuff that will go on the bike that I forgot about, so the bike will be pretty close to 20lbs when completed. Very cool!
I got a 2 piece titanium crank set from Garrie Hill a while ago to be used on this bike, it was hand made, had a 3/4" ti spindle and came with no bearings. It took a while to figure out how to retrofit it into a standard 1 3/8" 24TPI BB shell, but eventually I found that BullsEye Bikes manufactures a bearing set for a 7/8" spindle. After obtaining a set of those bearings, I took a trip to the WISIL Skunkworks to make a an adaptor for it. Bill and I had to drill out a 7/8"x.062" aluminum tube to 3/4" ID to get it all to slide together nicely. The next step was to shorten the spindle, because it was way wide. As the left crank just clamped onto the squared off end of the spindle (no taper!), it was reasonably easy to extend the squared off section further down the length of the spindle by machining it with the bench grinder. 

It would have been nice to have it machined professionally, but this did a decent job. Oh, did I mention that titanium is not easy to work with? It's really hard, so you can't just file it (unless you have a looong time). Also, it's slippery like brass so it's hard for a tool to get a bite into it, and it tends to gum up cutting tools. After I machined the flats I had to cut off the excess. I tried a regular hacksaw at first. Ha!. A diamond impregnated round hacksaw blade worked a lot better, but still took a long time. The crank set is all mounted on the bike now and is nice and light (and it matches the rest of the bike!).

2/04/03
Started building up the handle bars. I'm going to use the H style bars similar to those on the steel 'Cuda. That in combination with the remote steering should provide a compact and responsive steering system, as well as the ability to jam the bike into a full fairing. Also if you hold your hands up in front of you, they naturally want to hold a vertical bar that is angled in slightly. I used a straight 7/8" aluminum tube for the horizontal portion of the handle bars, and carbon fiber bar cons for the uprights. Standard brake levers slide onto the bar cons, and bar end shifters fit into the ends. I did have to file the insides of the bar end shifters expansion fittings a small amount to enable them to slide into the bar cons without binding. This makes a nice lightweight control package. My hands fit perfectly between the brakes and the shifters.

I got the final piece of chain. I'm using Sachs/SRAM PC80R chain, which has pierced side plates to reduce weight. Even so, the chain alone weighs about 3.5 lbs. Yikes! I'm now accepting donations of titanium chain.

Due to the fairly straight chain return line, I'll be using a chunk of chain tube rather than an idler to manage the return chain. This should keep the bike a bit lighter than if I had used an idler.

I received the Garrie Hill version II XL potato chip seat, which is beautifully constructed from carbon fiber and 2 layers of nomex honeycomb. It's lightweight and nicely shaped to boot. The seat came with a cool headrest which will come in handy when the seat is laid way back for racing.  

Due to the design compromises, the seat height is not incredibly low, at 10.5 inches. It's bolted to the mounting brackets the George provided for now, but I'll epoxy some brackets to the seat later that should be a bit lighter and stronger.

As you can see in the picture above, I turned the brakes around so they face backwards. I did this so that I could locate the handle bars a bit father forward, while retaining leg clearance. I wish I had thought of this before now, as it makes a much nicer handlebar package, and the cables will stay out of the way of my legs. Upon testing, it feels fairly natural to reach for the brakes with your thumbs rather than your fingers. It's also more aero, as the brakes are now behind your hands.

2/11/03
All the parts are now installed, and the bike has ballooned up to about 24 lbs on the bathroom scale. This weight will go down again after I get the carbon fiber offset front fork to replace the steel fork that is currently installed. Also the wheels I am using now are built for strength, not light weight, so in the future I'll need to get some weight weenie wheels for it. It's looking like this won't be a sub-20 pound bike, but could still get close. I could lose some weight with titanium bolts and chain too. Anybody know of a ti-chain company who wants to sponsor me for 4 chains? After measuring the ti-crank I found that it's total weight is about the same as a Dura-Ace crank and BB. On the other hand, the Murray CF crank is lighter, and much more Aero. Please contact me if you have a used one you'd consider parting with...


I drilled holes in the frame tube to run all the cables through. This worked out nicely, and provides a very clean look. This bike looks long, but when the seat is laid back all the way, my helmet will come very close to the rear wheel. 
I noticed some boom flex when cranking on it while stationary. Hopefully this won't be an issue. If it turns out to be a problem, the contingency plan is to put a layer of carbon fiber over the offending frame sections, this should stiffen it nicely.

The headrest  is incredibly light, and is made of a curved piece of carbon fiber. It attaches to the seat with velcro.

Here's a side view of the seat. This one differs slightly from the one Garrie made me for the steel 'Cuda a few years ago in that it's the same thickness all the way across, and has the edges covered with a layer of CF. Garrie also re-shaped the profile a bit. It's incredibly light!
 

Here's the Velokraft offset CF fork at Kamil's shop in Poland. It's beautiful. The brakes are toward the back of the fork, similar to the Razz Fazz. ETA is sometime this month, when Larry Zenger will get the forks, a custom CF low racer in size XS, and a custom CF aero handlebar.

3/14/03
While I'm waiting for the front fork, I'm trying to figure out how I should build a tailbox for the bike. I have pretty much decided to build a huge Coroplast tailbox now, and then add the complete head-out "practical" fairing later. I'm going to use a cut-up WISIL bubble for the nose cone, and Coroplast for the rest. The mongo Tailbox will be 5 feet long overall, 21 inches wide, and about 30 inches tall. 
3/24/03
The fork arrived last Monday and I spent my free time during the week fitting it to the bike and getting all the fiddly bits like brakes and the speedo in order. I also started working on the mother of all Coroplast tailboxes.
After a few nervous test rides and much adjustment the bike was ready for a Barrington Hills ride. Everything held together, and the bike felt fast, especially up the hills. I could climb almost all the hills in my big chainring when I used to have to drop to the smaller ring. It's amazing what loosing 15 lbs of steel will do to your climbing ability. The flexibility of the titanium seems to only be a nuisance while cranking at high RPM and heavy power. When my cranking gets to the natural resonance frequency of the frame, (about 110 RPM) the bike gets "bouncy".
3/31/03
Here's a better picture of the completed bare bike. The new fork has a much longer fork crown than I had designed for, so eventually I'll need to cut about an inch off of the bottom of the ti head tube to reduce the ride height and trail. The extra long Garrie Hill head rest lets me lean the seat back a bit more. 
4/7/03 - Maple Park 10 mile TT
I completed the MOAT (Mother Of All Tailboxes) just in time for the Maple Park TT. The first leg was straight into the 20MPH headwind for a couple miles, and I was able to keep a fairly steady 20MPH pace until turn around #1. As there was no warm-up, I immediately went into max VO mode, and just hoped I could keep it up for the whole race.
Unlike last year, I was able to successfully negotiate the U turn on the one lane country road. Then there was a short down wind run, and back into the wind. After turn around #2 (which I made again without stopping thank you!) it was time
to turn on the afterburners. I cruised practically the whole way back (downwind) at around 30MPH, and peaked at 35MPH just during the short down slope before the finish line. Man what a ride! I ended up third in the recumbent class at 25:14 (23.7MPH Ave). 
The next week at the Single Bong 20K TT  in Wisconsin I was able to sustain a 25.68MPH average!

In retrospect, I did not notice the slight frame bounce in either race, so I guess that's a moot issue.

8/21/03
Here I am racing at the Indy races in April '03. With this tailbox, I can ride at between 26 and 28MPH for a very long time, and can sprint to up over 30 for short times. Without it, it's more like 23 or so. 

I'm thinking now that much of the flex can be traced back to the fork. It will need to be replaced eventually...

12/23/03
I'm now considering sending the Ti-Cuda back to George to have him remove 6 inches from the frame. It turned out that even with the fairly relaxed seat it doesn't need to be as long. Bringing the wheel closer to the back of the seat should improve the unfaired speed when I make the wheel disk.

Original Ti-Cuda

Photo-retouch of Ti-Cuda after 6" shortening
In addition to making the bike faster, it should be lighter (12" less chain!), stiffer, and best of all, it will fit in the Barracuda streamliner fairing!

Also Garrie is working on the next revision of the CF seat. This one is an extended version of his 'Murrican seat.

3/5/04
Last weekend I regained possession of the ti-Cuda after it had been shortened from 60" wheelbase to a 54" wheelbase by George Reynolds, and Garrie had finished making the new CF 'Murrican seat and mounting brackets. George did a great job on shortening the bike and the welds were fantastic.

Actual shortened Ti-Cuda
3/12/04
This picture shows the CF clamp Garrie made to mount the seat to the ovalized titanium tube.
The new seat is beautiful, Garrie has really outdone himself. I spent my spare time the last 2 weeks putting it all back together. The bike now weighs 25lbs and I'm still not using any weight weenie parts. Seat height has not changed, it's still 12". A bit high for a low racer...

Next steps: New Velokraft offset front fork with side pull brake to replace current fork. Replace front wheel and Pantour hub with lightweight wheel. 

3/28/2005
Here's the bike with the final modifications. New Velokraft fork with caliper brake, no Pantour hub (doesn't need it!), American classic rear wheel and front hub, and Rotor Cranks. In this form, it weighs in at 24 lbs. I have put many miles on it in the past year, and it's a fast cruiser.
 
   

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