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Products > varicrank |
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With the revolutionary VariCrank plus
CompuTrainer or Velotron, you can
isolate and measure the effect of crank
length on your cycling performance.
Determine your optimum crank length the
scientific way and gain that extra edge!
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Quick Adjustment from 165mm to
185mm |
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No Effect whatsoever on Chain
Ring Alignment |
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Use with CompuTrainer, Velotron
Size Cycle and on or off road |
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Machined from 606IT6 Aluminum
Alloy |
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Standard Shimano bottom bracket
taper |
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Standard Shimano 130mm bolt
pattern |
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1 Year Warranty |
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In the past determining the correct
crank length for an individual cyclist
has been primarily a trial and error
process with limited basis in science.
Few bike shops offer sizes outside the
standard crank lengths of 170mm, 172.5mm
and 175mm. And testing the effectiveness
of different crank lengths on the road
is time consuming and often yields
inconclusive results because seperating
the effect of crank length from other
variables on the road is very difficult
if not impossible. The combination of
VariCrank with CompuTrainer/Velotron has
changed this situation because it is now
possible to change the single variable,
crank length, while leaving all the
others constant.
One protocol to establish a more
efficient crank length for level road
cycling follows:
(1) First Week
Set the Varicrank to match the cyclist's
current crank length to establish a
baseline measurement. Ride the
CompuTrainer in the Coaching Software
Ergo mode at a set wattage that can be
maintained for at least 30 minutes
without excessive effort for each crank
length and RPM session. For each testing
session first warm up on the
CompuTrainer for at least 10 minutes at
75 to 100 Watts, and do the coast down
calibration step. Adjust the press-on
force to 2.00 or as close to that as
possible. On the first day ride at 60RPM
for the 30 minute session and at the end
of the session record the average
heartrate and Pulse Power number. Repeat
this process at the same time of day for
2 more days at the same wattage level.
On day two, ride at 90RPM and day three
at 110RPM.
(2) Second Week
Adjust the VariCrank length either up or
down by 2.5mm and repeat the process. If
the average heart rate decreases (and
Pulse Power number increases) the new
crank length is more efficient. Continue
increasing or decreasing the crank
length until the average heart starts to
increase. The crank length which results
in the lowest average heart rate is the
correct crank length for level road
cycling. In addition, by looking at the
RPM and average heart rate you can
determine the most efficient cadence for
the athlete for each crank length.
Other protocols can be set up using the
CompuTrainer's ability to create hills
to determine the best crank length to
use in hilly country. Varicrank adjusts
quickly (less than a minute) to any
length from 165mm to 185mm in 2.5mm
increments. Since adjusting the crank
length has no effect on chain ring
alignment, no other time consuming
adjustments are are required. Hence, it
is entirely feasible to use VariCrank on
the road and to adjust the crank length
to match the terrain. VariCrank is
precision machined from 6061 T6
Aluminium Alloy and has a hard anodized
black finish. It is built to last
indefinitely, carries a 1 year limited
warranty, and is prodigiously strong. A
set of VariCrank weighs 2.2 lbs.
Patents have been applied for. |
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