Thunderbolt Mk II Plans
For ordering click here
-UPDATE 9/27/07 -
Yes, I still have these plans for sale
The most advanced and comprehensive trike on the market today can be built in your own shop using these comprehensive plans. Over 180 illustrations and detailed instructions make these plans second to none. For a detailed example click HERE.
The drawing above is of a Thunderbolt Mk II, 20
The Background of the Thunderbolt
In 1994 I went to work designing a trike with similar traits as the Mike Burrow's designed Windcheetah. The newly designed trike was refined and named the 'Thunderbolt'. The "T'bolt" as I nicknamed it, was a very high performance and low cost trike in it's day. Although a capable machine, it was not until I closed my business, that the recumbent market realized the potential of this product. In most categories, it was superior to anything available.
In 2002, the first Spitfire was produced. The Spitfire featured a reduced wheelbase and track, 38° seat angle, disc brakes and a smaller 24" rear wheel. This new trike design weighs less than any tadpole trike including it's micro-sized contemporaries. Not only is this trike lighter, it is stiffer, more stable, faster and much better looking than the venerable Thunderbolt or anything else on the market.
Thunderbolt Mk II 20
Using all the new technology developed for the Spitfire, I developed a version using all 20" wheels and called it the Spitfire ST. This new design dubbed the Thunderbolt Mk II 20 is basically a Spitfire ST with a 20X20 wheel configuration, fixed angle seat and different drops-outs).
Thunderbolt Mk II 26
For optimized performance, the newly released Thunderbolt Mk II 26 with a 20x26 wheel arrangement is now available. The larger rear wheel offers unsurpassed roll-over efficiency, better ride and a higher Gear/Inch range. The Mk II 26 also uses an Ergo Seat design that has increased lumbar support making it more comfortable and better looking. The reduced track option and increased wheelbase puts this trike on par with the ultra-high performance Spitfire RS.
A side view of the Thunderbolt Mk II 26
Work Required
The art of bicycle frame building is not for the faint hearted. Additionally, building a complex Cycle Car is no easy undertaking either. To complicate these matters, the Thunderbolt design requires lots of fabrication details. I have made several changes to simplify the design of this project and offer pre-fabricated parts at a reasonable price. Still, novice frame builders may find this project challenging. Improvising is a necessity for success, as materials and tools may not always be available. Since a well-designed jig requires advanced skills and machinery, I have designed the trike so that elaborate fixtures are no longer required.
The frame is constructed out of either 6061 or 7005 aluminum with some 5052 alloy aluminum sheetmetal. 7005 aluminum offers excellent strength and only requires a simple artificial aging to achieve near maximum strength. On the downside, tubing is hard to acquire. This frame can also be made of 6061, but an expensive heat treatment is required for maximum strength. Likewise, a heat treatment can be waived, but the tube wall thicknesses must be increased which also increases weight.
Welding aluminum is not for the first time novice. Therefore, take this project at your own risk. This trike can also be fabricated out of muffler tubing, but the performance of the frame will be greatly compromised. Therefore, the frame Aluminum is extremely easy to work with can be formed and machined without difficulty. In summary, aluminum is one of the best frame materials to use for building a trike.
Project Features
Over the last 10 years I have built an international reputation for outstanding detail of my instructions. The Thunderbolt Mk II, represents detail and accuracy on a much higher level. Each chapter is structured to include a Bill Of Material (BOM), Tool Requirements, Chapter Objective, comprehensive Instructions, Illustrations, Drawings, and a Final Review. Attention to every detail is included.
These plans are not a bunch of ambiguous drawings. This is a book that fully details every step of the building process. Created by a professional engineer and technical writer, these plans offer detail not found in any plans for any price.
A typical fully detailed drawing is shown above.
Above is an example of the detailed instructions, download the entire chapter here
Design Features
Single Piece Cross-Member
In most kits, the cross-members consist of two pieces of tubing that requires mitering and elaborate fixtures to properly mount it to the main tube section. The Thunderbolt Mk II uses a single formed piece of tubing that represents both cross-member tubes. This assembly is shown below:
The cross-member tube is securely placed into the forward main section tube using a hole saw cut-out, as illustrated below:
Adjustable Steering Geometry
Almost all production trikes use a fixed geometry system. A fixed geometry means that neither Caster or Camber is adjustable. The most common method for securing the Kingpin to the tricycle frame today is by using a standard bicycle headset. Obviously the tube interfacing with the inner race of the headset represents the Kingpin. The Kingpin secures the steering knuckles using a single-ended cantilever design. Although the materials for these steering systems are universal, they do not allow any geometry adjustments to the steering.
The Thunderbolt Mk II uses Rod-End Bearings as a way of securing the kingpin to the tricycle frame. These bearings have proven to be extremely reliable and effective. I first got the idea of using rod-ends from a local Go-cart shop. In fact most of what I learned about recumbent tricycles, I learned from the knowledgeable people at Cal Karts in San Jose, CA. I figured if these bearings were tough enough for Quarter Midgets, they must be good for recumbent trikes too.
Another reason I chose to use the adjustable rod-end bearings was to compensate for the frame distortion caused by welding or improper alignment. Since the usage of these bearings allows very loose tolerances, extreme trike frame alignment will not be a critical issue.
Rear Wheel Triangulation
Several Trike designs do not use a seat tube and/or seat stays to add support to the rear wheel. The flimsy chain stays results in a wheel that flops during hard cornering (commonly known as side loading effect). Although all these manufacturers dismiss this anomaly as benign, it does compromise the trikes handling capability and can lead to early frame failure.
To reduce rear wheel flop, the Thunderbolt Mk II uses a fully triangulated rear stay system. The weight penalty is only 10 oz, and the overall rear stiffness is excellent. Anything less is unacceptable.
Webbed Gusset Reinforcements
Web gussets add structural integrity to the trike design preventing it from flexing and from early frame fatigue. CroMo trikes are allowed to flex without fatiguing, so these structural supports are not as common on steel frames. The Thunderbolt Mk II uses a total of three of these structures to ensure extended reliability of the frame.
Chain Management
The T'bolt uses a single roller system. The single roller allows lower friction, lower cost, lower weight and lower noise. The passive side of the chain is routed through polypropylene sprinkler tubing, protecting it from dirt and grime.
Foldable Seat
With the seat folded over, the wheels and BB boom removed, the new T'bolt Mk II becomes a compact package that can be shipped UPS. The length of the frame is 56".
Direct Steering or Over-Seat Tiller
The Thunderbolt Mk II is available with a comfortable Direct-Steering Side Sticks (these are clip-on style handles that attach directly to the Steering Knuckles) or a sporty Over-Seat Steering Club Tiller.
OSS Joystick Style Tiller is now included in version 2.0 of the plans.
Although the example above shows a RS Spitfire, the tiller system used on the Thunderbolt Mk II is very similar and just as effective.
Specifications
(These values can differ depending how the trike is built and the components used)
Frame Description:
TIG welded 7005/6061 aluminum, artificially aged (T5 condition for 7005) (T6 for 6061).
Tube web-gussets on main boom (2 ea.) and on aft section with fully triangulated rear stays. Telescopic Bottom Bracket section for rider adjustment.
Dimensions:
Total Length : For average 5'10" rider configuration 74.5" (1,892 mm) Total Width : Mk II 20 35"(889 mm) Mk II 26 32"-35" Wheelbase : Mk II 20 40"(1,016 mm) Mk II 26 43"
Wheel Track : Mk II 20 32" (813 mm) Mk II 26 29"-32" Ground Clearance : Mk II 20/26 3.6" (91.5 mm)
Seat:
Description-Two section aluminum frame (fully re-enforced) covered with a Nylon Lanoloc mesh sling. . Seat Angle : Mk II 20 38°, Mk II 26 35° Seat Width at base : Mk II 20/26 18.5" (470 mm)
Seat Height : Mk II 20/26 ~32" (or around neck level or below) (813mm).
Seat to ground height: Mk II 20/26 7.5" to 8" (at low point) (190mm)
Steering System (for both 20/26)
