Bicycle Roller Racing Info
Past Events -- from 2001 to 2011
About Barelli Competition Rollers,
Bicycles and Gear Limits
by Dave Perry
© 2007 bikecult.com
Update Saturday, 31 December 2011
Barelli Competition Rollers
Manufactured by Barelli Ltd.
Viking Way, Bar Hill, Cambridge, England.
This quadruplet set includes four colored rollers, red, blue, black and green.
These correspond to four colored arrows on the 6-foot diameter dial clock.
On the middle cylinder of each roller is a sprocket wheel and gear box.
By way of a flexible transmission cable, the roller gear box is connected to
a similar gear box behind the dial face. This gear box drives it's corresponding
arrow on the dial face, by way of a roller belt drive system. The unit is human-powered,
mechanically driven, and totally wireless.
Roller material: hard plastic cylinders with aluminum side flanges.
Bearings: sealed cartridge.
Diameter: 6.5 inches or 16.5 cm.
Width: 15 inches or 38 cm.
Center band: 2 inches or 5 cm.
Height to floor: approx. 8 inches or 20.3 cm.
Maximum length (axle centers): 49 inches or 124.5 cm.
Minimum length: 46 inches or 117 cm.
Front roller adjust: 1 inch or 2.5 cm.
Rear roller adjust: 2 inches or 5 cm.
Roller belts (4): Clear poly 3/16" x 70".
Dial belts (4): Red poly 5/16" x 34".
The equation for the sizing the dial belts is A plus B equals X plus C minus D. A is one-half the dial circumference.
B is one-half the belt-cog circumference. C is dial center to cog center times two.
D is stretch variable of minus 15 percent. X is circumference of belt.
When setting up a bicycle on rollers, the front wheel axle center should
fall slightly behind the front roller axle center.
The front tire's contact point is also behind the top of the roller.
For these rollers the ideal distance behind is 3/4 to 1-1/8 inches or 2 to 3 cm.
It seems these rollers were designed to fit racing bicycles with a long wheelbase.
When adjusted for minimum length (46 inches) it's a near perfect fit for a typical
track bike with tubular tires and a wheelbase of 38 inches or 96.5 cm.
Bikes with a wheelbase less than 37.5 inches or 95 cm, may touch too far behind
the front roller, resulting in a difficult ride.
One lap of the dials equals 500 meters. Our typical roller races include
one-lap qualifying rounds of 500 meters, with two-lap finals of 1,000 meters.
The races usually begin with a standing start, with the dials lined up at the top.
The program of events usually begins with timed qualifying rounds of four racers.
Depending on number of participants, each racer gets two chances to make their best time.
Racers are seeded by time and enter a round-robin tournament. Sometimes the whole field
is included, other times the top eight proceed. The winners go on to semi-finals,
losers go to repechage (or to the bar) to decide the lower placings. Finals decide top four.
The moving arrows are the only indicator of performance with these rollers.
Official timing is done by stop watch and the scoreboard is a results
sheet on an easel. In a close-finish race, or one that's too close to call,
a video camera is used to split the arrows apart and decide who finished won.
Racers are encouraged to bring their own speed, cadence, heart rate and power meters.
We've held races with and without a gear limit.
A gear limit is used to make the race fair and even, to discourage any advantage among racers.
These rollers have low rolling resistance which allows for high speed spinning.
Racers are encouraged to use the biggest gear up to the limit.
USCF Roller Racing Regulations:
"1J4. In roller races, either road or track bicycles may be used.
All classes are restricted to a development of 7.69 meters
(25 feet 3 inches), and cranks must be at least 165 millimeters long."
--from 2006 USCF rule book
Development is the distance the rear drive wheel travels in one
revolution of the pedal cranks. A roll-out test is used to measure
development, by making a long straight line on flat ground.
A bicycle is placed along the line with the drive wheel axle intersecting a starting point,
and the cranks set at top or bottom resting position.
The cranks are rotated forward one complete revolution. The bike rolls out
an exact distance, the development, which is measured along the line where the drive wheel axle
intersects. Development can also be calculated by gear ratio
and tire circumference, but this is not official nor as precise as a roll-out test.
A typical race bike with 2.095 tire circumference (700x23 clinchers or tubulars),
with a development of 7.69 meters (25 feet 3 inches or 303 inches),
would have to have a 3.67 gear ratio and a 99.1-inch gear.
By comparing gear ratios and tire sizes, the closest possible combination,
according the tables shown below, is the 7.83 meter 44 x 12 with 700 x 23 tires.
Note that this roller racing gear limit of 7.69 meters is lower than
the USCF Junior road racing gear limit of 7.93 meters, and higher than
the USCF Juniors 15-16 years track racing gear limit of 6.78 meters.
Here are tables of measure for various gear combinations
and common tire sizes. These are approximate
measurements, distances may vary.
RATIO (GEARS) X CIRCUMFERENCE (TIRE SIZE) = METERS DEVELOPMENT
3.692 (48 x 13) X 2,096 mm (700 x 23 clincher) = 7.739 m development
3.642 (51 x 14) X 2,116 mm (700 x 28 clincher) = 7.706 m development
3.692 (48 x 13) X 2,085 mm (27" x 22 tubular) = 7.697 m development
3.666 (44 x 12) X 2,096 mm (700 x 23 clincher) = 7.683 m development
3.642 (51 x 14) X 2,108 mm (700 x 25 clincher) = 7.677 m development
3.615 (47 x 13) X 2,116 mm (700 x 28 clincher) = 7.649 m development
3.642 (51 x 14) X 2,096 mm (700 x 23 clincher) = 7.633 m development
3.636 (40 x 11) X 2,096 mm (700 x 23 clincher) = 7.621 m development
3.692 (48 x 13) X 2,064 mm (700 x 20 clincher) = 7.620 m development
3.615 (47 x 13) X 2,108 mm (700 x 25 clincher) = 7.620 m development
3.600 (54 x 15) X 2,116 mm (700 x 28 clincher) = 7.617 m development
3.642 (51 x 14) X 2,085 mm (27" x 22 tubular) = 7.593 m development
3.600 (54 x 15) X 2,108 mm (700 x 25 clincher) = 7.588 m development
3.615 (47 x 13) X 2,096 mm (700 x 23 clincher) = 7.577 m development
3.600 (54 x 15) X 2,096 mm (700 x 23 clincher) = 7.545 m development
3.642 (51 x 14) X 2,064 mm (700 X 20 clincher) = 7.517 m development
3.545 (39 x 11) X 2,116 mm (700 x 28 clincher) = 7.502 m development
3.533 (53 x 15) X 2,116 mm (700 x 28 clincher) = 7.475 m development
3.533 (53 x 15) X 2,096 mm (700 x 23 clincher) = 7.405 m development
The thing about roller racing is that each performance can be
accurately calculated by cadence, development, distance and time.
We can see how this plays out in a 500 meter event by comparing two racers
with different cadence and development. Imagine one racer riding a road bike with
a 53 x 15 on 700 x 23 clinchers, giving 7.40 meters development. The other
racer rides a track bike with a 48 x 13 on 27" x 19 tubulars, giving 7.66
meters development. That's a 26 centimeter advantage per pedal stroke.
Furthermore, in those 500 meters, the road rider can expect to do exactly
67.5 crank revolutions, and the track rider will do 65.2 revs, two less
pedal strokes over the same distance. Then the time to beat is 18 seconds.
Roadie must do 3.75 revolutions per second, an average cadence of 225 rpm,
while trackie has to do 3.62 revs per second, an average of 217.5 rpm.
Drying towels for athletes and roller drums.
Timing equipment, stop watches.
Floor pump with gauge.
Entry & release forms.
Scoreboard & easel.
Markers and pens.
Volunteer holders & spotters.