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Barelli Competition Rollers


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Bicycle Roller Racing Info

Technical Details
About Barelli Competition Rollers,
Bicycles and Gear Limits

Rollers Home: about these & other rollers
Past Events: from 2001 to 2013

by Dave Perry
© 2000--2014 bikecult.com
Update Wednesday, 12 November 2014

This colorful set of racing rollers with clock face comes from the late 1960s England. I bought it at a Sotheby's auction in Chicago 2000. These had been used during half-time of pro basketball game in Denver? And was Greg Lemond a rider there? Anyway, the rollers are dedicated to my mom and they continue to rollout at new venues each year.


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 black PVC cylinders with aluminum side flanges.
Bearings: sealed cartridge.
Drum diameter: 6.5 inches or 16.5 cm.
Drum width: 15 inches or 38 cm.
Drum 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.

Setting Up

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.

Racing Format

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.

Gear Limit

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 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.

Development Tables

Here are tables of measure for various gear combinations and common tire sizes. These are approximate measurements, distances may vary.


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.


Measuring tape.
Drying towels for athletes and roller drums.
Timing equipment, stop watches.
Floor pump with gauge.
Entry & release forms.
Markers and pens.
Volunteer holders & spotters.