The Alpha Cycle
Code Name: The "Little King Alpha" Project
09 December 2002, by Jon Sharratt - Web Page by Mark Stonich
jon.sharratt@mts.com
Frame and Fork Features
  • Started as a way to build a curved frame using straight pieces
    • 4130 CrMo throughout
    • 1.75" x .049 main tubes
    • 2" x .049 cross tubes
    • Silver brazed
  • Segment frame construction features design flexibility and ease of assembly
    • Cross tubes and segments can easily be changed to any angle during design or construction (12 & 37 degrees in this example)
    • Laying the frame on a flat surface to tack weld results in a straight frame
    • Frame gussets double as cable guides
  • CNC'd rear dropouts with the help of Alpha Engineering & Manufacturing
    • Started 27 December 1999!
  • Modified Waterford fork
    • Reynolds 531 blades, Henry James fork crown
    • Sleeved construction
    • Raked by Ray Brick
    • Reinforced fender mounts
    • Integral brake reaction arm mount
  • Rear fork
    • Made from Trek mountain bike fork blades
    • Brass brazed
  • Rear suspension
    • Simple design uses 3/8" automotive fuel line hose as an elastomer
    • Telescoping struts made from 3/8 x .035 and 7/16 x .028
    • Elastomer stops made from common washers
    • Aircraft clevis from Aircraft Spruce & Specialty provides pivot
Seat Details
  • Earth Cycles frame and mesh
    • Tig welded 5/8 x .035 CrMo
  • Pylon mount
    • Slides fore and aft on main frame
    • Offset to prevent interference with frame joint
    • Anti-rotate provided by 1/8” stainless rod brazed to side of frame
    • Lateral location by small pins brazed into seat frame
    • Breakaway design held in place by heavy duty zip ties
    • Both mounts pivot to accommodate suspension movement
    • Seat angle adjusted by changing length of fuel line hose
Drivetrain Features
  • 68 tooth TA chainring
  • 155mm TA crankarms
  • Boone Technologies “Helixx” titanium BB
  • 125mm Q-factor
  • Be-Bop pedals
  • Chain tensioner
    • 12 tooth Shimano derailleur pulley
    • Internal spring anchored by tiny spoke and nipple
    • Anti-rotate peg
    • Star Trek communicator shape
    • Provides cable guides and computer mount
  • Mid-drive
    • Positioning the largest cog to the outside provides better chainline
    • 3 self-aligning bushings mate the cassette to the frame and provide a mount for the front derailleur hanger
    • 3/8” crosstube inside the frame for strength
    • Standard 7-speed cassette body modified so cogs can be reversed for correct chain ramp orientation
    • 4 front cogs expandable to 5 (possibly 6) with wider cassette body
  • Backwards front derailleur for “pre-selector” shifting
    • Mover the lever then shift the front by pedaling backwards ¼ turn
    • Shifting possible while sitting still
    • 2 short cage derailleurs for better ground clearance and plenty of chain wrap
  • 7-speed Sachs rear freewheel
  • 28 speeds total, expandable to 35
Brakes
  • Sturmey-Archer drum brakes with nutted axles
    • No trouble with clearance at the fork crown, no cantilever posts, great bearings
  • Modified aero-bar brake levers
  • Brazed torque reaction mounts front and rear
Biplane Rack (lower section only at this time)
  • Made from 3/8 x .028 and ¼ x .028 CroMo, silver brazed
  • Joining lugs and dropout bosses made from stainless steel
  • Drive chain passes through it
  • Comes apart in 5 pieces
  • Hanging bottle mount
  • Breakaway design held in place with zip ties
  • Proper width for tail box attachment
  • Upper level (not completed) tapered for tail box and positioned flush with rear tire for standing on end
Handlebars and Stem
  • Handlebars adjustable for width, made from old aluminum crutches
  • Hand carved stem with Internal clamps
Other Details
  • Steering lock for storing bike on end (see rack description)
  • Plastic mudguards from Luke at Calhoun Cycles
  • Custom stainless steel mudguard mounts
  • Bottle Opener
Specifications
Weight		34 lbs
Length		70 in
Wheelbase	45 in
Width	 	15 in
Height	 	36 in
Seat height 	17 in

          Head angle		72 deg.
          Trail			.25 in
          Gear range		24 – 130"
          Cost guess		$1200
          Time to completion: 	3 years (but the biplane rack isn't done yet)
Resources
Tubing: 	Aircraft Spruce & Specialty		http://www.aircraftspruce.com/
TA cranks: 	Bike Specialties, Toronto		http://www.bikespecialties.com/
Other parts:	Calhoun Cycles			http://www.calhouncycle.com/
Powder coating:					http://www.powdercoatingtech.com/
More frame details: 			http://mnhpva.org/meetings/Mar_02/Jon.html
More fork details:			http://mnhpva.org/meetings/Feb_02/JonFork.html
More Biplane rack details:		http://mnhpva.org/meetings/May_02/JS.html
Software: Intergraph SmartSketch	http://www.intergraph.com/ppo/smartsketch/
Alpha Engineering & Manufacturing:	763-542-8860   Todd Sorlie tns@skypoint.com

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