PVD Land Speed Record Bike

Team McCall USA

Gordon McCall was put in touch with me through my friend Dan Kyle. Dan is a motorcycle tuner that knew that I knew a lot about building bicycle frames as well as motorcycle science. see: Team McCallUSA

Previous Record Bike

Fred Rompelberg is the current record holder. 268.831 km/h. 167.044 mph.

This is as close a scetch of Fred's bike that I could make from photographic details. The wheels are about 22 inches in diameter.

Rough Print for Team McCall USA Bike

The Frame

The frame will be constructed of 4130 tubing. The goal is to make the bike as light as possible, as stable as possible, as fast as possible, and most importantly AS SAFE AS POSSIBLE.

At speeds over 170mph, the forces going through the frame are huge even on apparently smooth surfaces.

At this point, the bike is going to have front suspension and a solid rear for maximum power transmission. The tire in the rear will be doing most of the work.

Tubing Choices

Special tubes avalable:

True Temper Tandem Boom Tube, F1-TDBT, 2.125 x 1.375 Oval x 0.9mm Wall x 692mm Long ($32.40 from Henry James)
Reynolds 525 Tandem Base Tube, KC120, 1.968 (50mm) x 0.984 (25mm) Oval x 0.035 (0.9mm) Wall x 760mm Long
Reynolds 525 Tandem Base Tube, KC111, 1.500 (38.1mm) Round x 0.039 (1.0mm) Wall x 760mm Long
Reynolds 853 BX2709, 34mm x 28mm Oval x 650mm Long, 7/5/7 Butted
Reynolds 853 BX2805, 34mm x 28mm Opposed Oval x 635mm Long, 7/5/7 Butted
Columbus Cyclex, TCMA22, 48mm x 28mm Oval x 1.2mm wall x 680mm Long.

Weights

Weights:

Front Wheel - 12.30 lbs (tires - 6.25 lbs, rims - 6.05 lbs)
Rear Wheel - 12.30 lbs
Left Fork Leg - 6.05 lbs
Right Fork Leg - 6.05 lbs
Front Rotor - 3.60 lbs
Front Caliper - 1.60 lbs
Front Master - 0.90 lbs

Total weight of what you gave me - 42.80 lbs.

Lets say we can shave a pound of weight from each wheel, then we are down to 40.80 lbs.

My estimate of the additional parts:

Triple clamp and steerer - 3.50 lbs.
Head Bearings - 0.50 lbs
Axles - 0.75 lbs
Stem, Seat, Seatpost, Handlebars, Grips, Front Cranks, Front BB, Pedals - 5.50 lbs.
Sprocket adapter to rear wheel - 0.75 lbs
Double/Triple Reduction Gearing, Spindles, and Chain - 4.00 lbs
Steering Damper - 1.00 lbs
Paint and Decals - 0.50 lbs.

16.50 additional pounds (very rough estimate).

That brings us to 57.30 lbs BEFORE I even add the frame which will probably be at least 12 lbs.

I am very concerned about the amount of energy required to accelerate a 70 lb bike.

Some decisions really have to be made. I'm really thinking about this right now. I'm looking for the eureaka moment.

The Wheels

Marchesini 125 GP forged magnesium Wheels, 2.50”x17”, 63.5mm x 431.8mm

The current record bike used 18" diameter rims.

One concept is to lace some downhill bicycle hubs to some Excel 2.50x17" alloy rims with either 32 (XS32U, EFS32U) or 36 (XS36U, EFS36U)holes. Larger sized bicycle spokes could be used to save weight and using a radial lacing pattern.

RK-Excel USA
Claimed rim weight - 4.0 lbs

The spokes could be DT Champion 2.34mm spokes.

also, 12 gauge, 2.6mm, 0.104" spokes from Central wheel

Then the issue is to make a safe tubeless conversion.

The Tires

Donlop Tires is helping us with some killer rubber. We really need to use the fastest hardest rubber that they have available. We also need to use the smallest tire.

The current record bike used tires with a diameter of 20.4 inches on 18 inch rims.

KR149
(125cc slicks)
95/70x17

6.25 lbs.

C-Medium Compound

Rim Range - 2.15-2.5"
Recomended rim - 2.5"
Max width - 3.46"/88mm
Max Diameter - 22.68"/576mm
Suggested Roadrace psi - 25-27

I wish that we could find something that was a lower profile, like the rain tire but with hard compound and slick.

KR122
Compound- WA
Max Width - 3.45"/88mm
Max Diameter - 22.64/575mm

The tires will probably need to be shaved to reduce contact patch and to save grams.

Tires should be W (168mph) or Y (186mph) rated.

The Fork

Ohlins 125 GP gas fork

options:

Fox 40, 6.83lbs
Marzocchi 888, 6.98 lbs
Rock Shox Boxxer, 6.2lbs

The Yoke

A special lightweight yoke is going to be required. The goal is to have a 1.125" steerer extention so that different stems can be redily avalable for rider position adjustment. I think that this makes sence.

Risse Racing (not contacted yet). 1.5" offset.

If not available, then DKG

or Dan Hanebrink, this link may work better.

The Brakes

Brembo 125 GP

16x18 Radial brake master cylinder for single caliper

155mm rotor front?

The Headstock & Bearings

The larger the headstock the better. Current bicycle technologies are durable and light. The Cane Creek Double XC 1.5" Flush headset should maximize the headstock area.

The Dropouts

In house design, watejet cut from .3125 4130 Cro-mo.

It has not been decided if the rear wheel postion will be fixed or adjustable.

The Drivetrain

Cranks- Dura-Ace Track cranks

Jack shaft-

Gearing

A reduction of 19.5 to 20 times reduction will be needed to get the bike over record speed at 130rpm crank speed.

Double or Triple Reduction

A triple reduction with a front freewheel can use 53/19-53/19-53/21 for a 19.64 reduction.

A double reduction will require a 65/14-65/15 for a 20.12 reduction. (65 tooth rings are available)

Or if custom rings are made, then 76/17-76/17 for a 19.98 reduction

The triple reduction chain wraps 1231 degrees per crank rotation. (but the added weight and drag from the additional drivetrain reduces the effiecincy of this option considerably.

The double reduction with the 65 tooth rings is a little less efficient since the chain wraps 1267 degrees per crank rotation.

The double reduction with the 76 tooth rings is much more efficient than either of these options with 1088 degrees of wrap per crank rotation. About 14% more effiecient due to chain friction.

So, Custom rings must be made with 76 or more teeth.

Other Details

Sprockets- Paragon, Phil Wood, or White.

A better choice could be Highpath Engineering

MDT does ovals as customs. These run in the $500 each range.

http://www.rotorcranks.com/s1-q-rings.shtml

65 tooth 130mm chainring

Schlumph

144 BCD to match the Dura-ace track cranks. 5/16-3/8" thick.

To match the current record on the wheels that have been selected at 130 crank rpm, we will need twin 70/16 reductions. Twin 74/17 comes quite close, but comes just short. It's obvious that some refinement is needed here. Breaking the record will require a slightly taller gear.

The rear wheel will be spinning approximately 2500 rpm. Front crank 130 rpm. Jack shaft, 570 rpm.

17 teeth is a minimum for high speed drive systems.

The current world record bike used double reduction gearing, 70/13 teeth & 60/15 teeth, an overall reduction of about 21.5 and 114.2 ft of development. The bike used tires mounted on 18" rims with an overall diameter of 20.4 inches.

At 13 inch spacing between a 74 tooth ring and a 16 tooth ring, the included chain angle will be 41.5 degrees, a wrap angle of 138.5 degrees. 120 degrees is considered the minimum for any roller chain drive. The planned gearing range should be sufficient.

Where P is the pitch of the chain, and N is the number of teeth on the sprocket;

Pitch Diameter = Chain Pitch / Sin (180/Teeth)

Outside Diameter = P × (0.6 + cot ( 180° ÷ N) )

Sprocket thickness = 0.93 × Roller Width - 0.006"

Maximum Pitch = (900 ÷ rpm )^2/3

Chain

Bushing or bushinless?

400 series chain?

Bushingless 8spd Dura-ace chain or bushingless 10spd Dura-ace?

The chain will be moving at 21651.5 inches per minute at record speeds. That is 1804.3 ft./min.

Centrifugal pull = (chain weight per foot x (fpm)^2)/115,900 Total chain tension = working load + cenrifugal pull

Generic 25 series chain weight - 0.9 lbs per foot.

Ceramic Bearings

Expected cost - $600 for both wheels, $300 for both bottom brackets.

Testing

Record Attempt

The record attempt will be made at Bonneville or Edwards Airforce Base.

Research Links