 |
|
|
Renthal front and rear sprockets
are used by many of the World's
top Road Racers, but why are
riders using Renthal products
so successful?
Renthal
road racing products are designed
and engineered specifically
for road racing and normal road
use too and are then exhaustively
tested by the world's best riders
as part of Renthal's ongoing
development process. So they
know they have the world's best
sprockets fitted to their bike,
sprockets they can rely upon
100%.
And,
any rider using Renthal products
purchased from HPS, has exactly
the same parts on his or her
bike as those used by the best
riders in the world! |
|
| RENTHAL
- WE BUILD CHAMPIONSHIPS... |
| |
| 2001
WORLD SUPERBIKE |
|
| Team |
Riders |
| Castrol
Honda |
Colin
Edwards, Tadayuki Okada |
| Kawasaki
Racing Team Eckl |
Akira
Yanagawa, Gregorio Lavilla, Hitoyasu
Izutsu |
| GSE
Racing |
Neil
Hodgson and James Toseland |
|
|
 |
Castrol
Honda
Colin Edwards, Tadayuki Okada |
Kawasaki
Racing Team Eckl
Akira Yanagawa, Gregorio Lavilla, Hitoyasu
Izutsu |
| ___________________________________________________________________________________________ |
2001 WORLD 600 SUPERSPORT |
| Team |
Riders |
| Team
Dienza Ducati |
Vitto
Guareschi and Dean Thomas |
| Castrol
Honda |
Chris
Vermeulen |
| Kawasaki
Racing |
Iain
MacPherson and Andrew Pitt |
| Team
Ten Kate |
Pere
Riba, Fabien Foret |
|
| ___________________________________________________________________________________________ |
2001 UK SUPERBIKE
|
| Team |
Riders |
| GSXR
Factory squad |
John
Crawford |
| Red
Bull Ducati |
John
Reynolds and Sean Emmett |
| Virgin
Yamaha |
James
Haydon and Jamie Robinson |
| Monster
Mod Ducati |
Steve
Hislop |
| Kawasaki |
Steve
Plater |
| Dienza
Ducati |
Paul
Brown |
|
| ___________________________________________________________________________________________ |
| |
| Aluminium
alloy rear sprockets Racing and Road use |
 |
Precision
CNC manufactured to extremely tight
tolerances from a high strength, specially
enhanced 7075 T6 aluminium alloy, Renthal
sprockets have unequalled accuracy of
fit, tooth profile and concentricity
for longevity and maximum power transfer.
Maximum
reduction of unsprung revolving weight
at the rear wheel, through a combination
of the choice of material and design
ensures maximum power transfer. Renthal
rear wheel sprockets are 33% of the
weight of steel yet incredibly durable.
Available in silver etched finish, titanium/bronze
coloured hard anodised and from HPS
in Gold too.
|
| |
| |
| Case
hardened front Sprockets for Racing and
Road use |
Precision
CNC manufactured to extremely tight tolerances
from a case hardened and core refined
655M13Nickel-Chrome-Molybdenum alloy steel
used to give the ultimate combination
of strength and hardness.
Advanced design ensures minimum weight
while retaining maximum strength.
|
| Renhtal
Chain and Sprocket Fitting Notes
When fitting new sprockets it is
very important that a new chain is fitted
at the same time, and vice versa. Using
an old chain with new sprockets, or
a new chain with old sprockets will
cause rapid wear.
During use a chain will stretch (i.e.
the pins will wear causing extension
of the chain). To measure how much a
chain has stretched, put the motorcycle
in gear and rotate the rear wheel to
tension the top strand of the chain.
Measure accurately (ideally with a vernier)
16 links, counting both roller and pin
links. If the length of the measured
16 links is greater than the maximum
acceptable length given in the table
below then the chain should no longer
be used. These figures assume a 2% maximum
allowable extension for non 'O'-ring
chain and a 1% maximum extension for
'O'-ring chain. |
|
| |
Using a chain which has been stretched
more than the above maximum allowance
causes the chain to ride up the teeth
of the sprocket. This causes damage to
the tips of the chainwheels teeth, as
the force transmitted by the chain is
transmitted entirely through the top of
the tooth, rather than the whole tooth.
This results in severe wearing of the
chainwheel.
Misalignment of front and rear sprocket
is a major cause of rapid wear. Chains
and sprockets should be checked for worn
spots which could indicate misalignment.
Misalignment is usually due to not adjusting
the chain tensioners an equal amount on
both sides, worn wheel bearings or worn
swinging arm bushings. To check the alignment
put the bike on a stand, spin the rear
wheel and watch how the chain travels
along the sprockets. The chain should
run on the centre of the teeth, it should
not run to one side or snake from one
side to the other.
|
CORRECT
|
INCORRECT
|
INCORRECT
|
These
diagrams show two examples of
misalignment which must be avoided.
A long rule should be used to
avoid these whist setting up.
The front sprocket must be aligned
within 1 mm (0.04") of
the straight edge.
Lack of lubrication is a common
cause of chain and sprocket
wear. Check your chain is well
lubricated. Neglecting a chain
will cause it to rust.
Your chain snapping can cause
expensive damage to your bike.
If your chain is damaged, worn
or overstretched, replace it
now.
Renthal chain and sprockets
are a perfectly matched, hard
wearing, high quality replacement
for you existing final drive.
Checklist - when fitting new
chain and sprockets ensure that:
- You
do not mix old and new chain
and sprockets.
- The sprockets are correctly
aligned.
- The chain and sprockets are
well lubricated.
Renthal Chain - good for your
teeth.
|
|
| More
Technical Information Regarding, Sprockets,
Gearing and Chain
Reproduced by kind permission of Renthal |
| |
Introduction
to TORQUE, WORK and POWER
Torque is the twisting force about a point,
sometimes called a 'moment'. The torque
is defined as the force multiplied by
the distance from the pivot perpendicular
to the force. |
 |
| For
example: One foot pound of torque is
the twisting force necessary to support
a one pound weight on a weightless horizontal
bar, one foot from the pivot. You might
directly measure torque when tightening
a nut to a specified torque using a
torque wrench. Here, a twisting force
is applied to the nut, until the resistance
to rotation of the nut is equal to the
torque required.
Work is the the transfer of energy.
The work done is equal to the force
applied multiplied by the distance travelled
in the direction of that force.
|
 |
| TravelledPower
is the rate of doing work, the amount
of work done in a unit of time. The power
produced is the work done divided by the
time taken. |
 |
| For
example: If a weight is fixed solidly
to the floor and you try to lift it,
you are applying force. However the
weight cannot move, so no work is done
on the weight. Although force is exerted
by your arms, no energy is transferred
to the weight. If you lift a one pound
weight one foot, then by definition
one foot pound of work has been done.
If you take one minute to do this then
you will be producing power at one foot
pound per minute.
One horsepower is 33,000 foot pounds
per minute. To find the horsepower of
an engine, the torque produced by the
engine is measured and the horsepower
calculated. This is done using a dynamometer
which is essentially a brake with a
measuring device - hence the term brake
horse power (bhp) which is often used.
A torque curve is produced by plotting
the torque measured against the engine
speed.
With torque in foot pounds:
|
 |
| Using
this equation a power curve can be produced
from the torque curve. |
| |
| How
does this apply to a motorcycle? |
| For
the rider, torque is the all-important
factor. A bike will accelerate at a
rate that matches its torque curve (ignoring
rolling / air resistance). The torque
peak is the point at which the bike
has maximum acceleration, either side
of this peak it is less. For a given
torque at the rear wheel, the acceleration
of the bike is the same, irrespective
of the engine speed. Horsepower increases
with the engine speed until well after
the torque peak, and only peaks when
the decreasing torque compensates for
the increasing rpm. (look at the equation.)
The acceleration at the torque peak
is greater than that at the power peak.
So why do we talk about horsepower so
much? Consider a large waterwheel. While
it's obvious that the water wheel generate
a large torque, its rotational speed
is very slow and hence its power (the
ability to do work over time) is low.
A waterwheel is therefore not generally
very powerful. A powerful engine with
lots of horsepower is one which produces
high torque at high rpm.
Theoretically, producing torque at high
rpm is better than producing torque
low rpm, as at high rpm you can use
gearing. A powerful engine is useful
because it can then be geared down -
you don't want the rear wheel of your
bike doing 8000rpm anyway! Gearing down
reduces the speed at the rear wheel
with a corresponding increase in torque.
This does not affect the power of the
engine apart from frictional losses.
Incidentally a properly lubricated chain
drive is 98.5% efficient, significantly
better than a geared drive. For road
racing, this theory closely matches
reality, but for offroad the above is
not the only consideration. (still awake?!...)
|
|
Front and rear sprocket size gearing
calculation chart |
| But
what does that mean about gearing... |
| |
Ö10 |
11 |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
| 65 |
6.5 |
5.91 |
5.42 |
5 |
4.64 |
4.33 |
4.06 |
3.82 |
3.61 |
3.42 |
3.25 |
| 64 |
6.4 |
5.82 |
5.33 |
4.92 |
4.57 |
4.27 |
4 |
3.76 |
3.56 |
3.37 |
3.2 |
| 63 |
6.3 |
5.73 |
5.25 |
4.85 |
4.5 |
4.2 |
3.94 |
3.71 |
3.5 |
3.32 |
3.15 |
| 62 |
6.2 |
5.64 |
5.17 |
4.77 |
4.43 |
4.13 |
3.88 |
3.65 |
3.44 |
3.26 |
3.1 |
| 61 |
6.1 |
5.55 |
5.08 |
4.69 |
4.36 |
4.07 |
3.81 |
3.59 |
3.39 |
3.21 |
3.05 |
| 60 |
6 |
5.45 |
5 |
4.62 |
4.29 |
4 |
3.75 |
3.53 |
3.33 |
3.16 |
3 |
| 59 |
5.9 |
5.36 |
4.92 |
4.54 |
4.21 |
3.93 |
3.69 |
3.47 |
3.28 |
3.11 |
2.95 |
| 58 |
5.8 |
5.27 |
4.83 |
4.46 |
4.14 |
3.87 |
3.63 |
3.41 |
3.22 |
3.05 |
2.9 |
| 57 |
5.7 |
5.18 |
4.75 |
4.38 |
4.07 |
3.8 |
3.56 |
3.35 |
3.17 |
3 |
2.85 |
| 56 |
5.6 |
5.09 |
4.67 |
4.31 |
4 |
3.73 |
3.5 |
3.29 |
3.11 |
2.95 |
2.8 |
| 55 |
5.5 |
5 |
4.58 |
4.23 |
3.93 |
3.67 |
3.44 |
3.24 |
3.06 |
2.89 |
2.75 |
| 54 |
5.4 |
4.91 |
4.5 |
4.15 |
3.86 |
3.6 |
3.38 |
3.18 |
3 |
2.84 |
2.7 |
| 53 |
5.3 |
4.82 |
4.42 |
4.08 |
3.79 |
3.53 |
3.31 |
3.12 |
2.94 |
2.79 |
2.65 |
| 52 |
5.2 |
4.73 |
4.33 |
4 |
3.71 |
3.47 |
3.25 |
3.06 |
2.89 |
2.74 |
2.6 |
| 51 |
5.1 |
4.64 |
4.25 |
3.92 |
3.64 |
3.4 |
3.19 |
3 |
2.83 |
2.68 |
2.55 |
| 50 |
5 |
4.55 |
4.17 |
3.85 |
3.57 |
3.33 |
3.13 |
2.94 |
2.78 |
2.63 |
2.5 |
| 49 |
4.9 |
4.45 |
4.08 |
3.77 |
3.5 |
3.27 |
3.06 |
2.88 |
2.72 |
2.58 |
2.45 |
| 48 |
4.8 |
4.36 |
4 |
3.69 |
3.43 |
3.2 |
3 |
2.82 |
2.67 |
2.53 |
2.4 |
| 47 |
4.7 |
4.27 |
3.92 |
3.62 |
3.36 |
3.13 |
2.94 |
2.76 |
2.61 |
2.47 |
2.35 |
| 46 |
4.6 |
4.18 |
3.83 |
3.54 |
3.29 |
3.07 |
2.88 |
2.71 |
2.56 |
2.42 |
2.3 |
| 45 |
4.5 |
4.09 |
3.75 |
3.46 |
3.21 |
3 |
2.81 |
2.65 |
2.5 |
2.37 |
2.25 |
| 44 |
4.4 |
4 |
3.67 |
3.38 |
3.14 |
2.93 |
2.75 |
2.59 |
2.44 |
2.32 |
2.2 |
| 43 |
4.3 |
3.91 |
3.58 |
3.31 |
3.07 |
2.87 |
2.69 |
2.53 |
2.39 |
2.26 |
2.15 |
| 42 |
4.2 |
3.82 |
3.5 |
3.23 |
3 |
2.8 |
2.63 |
2.47 |
2.33 |
2.21 |
2.1 |
| 41 |
4.1 |
3.73 |
3.42 |
3.15 |
2.93 |
2.73 |
2.56 |
2.41 |
2.28 |
2.16 |
2.05 |
| 40 |
4 |
3.64 |
3.33 |
3.08 |
2.86 |
2.67 |
2.5 |
2.35 |
2.22 |
2.11 |
2 |
| 39 |
3.9 |
3.55 |
3.25 |
3 |
2.79 |
2.6 |
2.44 |
2.29 |
2.17 |
2.05 |
1.95 |
| 38 |
3.8 |
3.45 |
3.17 |
2.92 |
2.71 |
2.53 |
2.38 |
2.24 |
2.11 |
2 |
1.9 |
| 37 |
3.7 |
3.36 |
3.08 |
2.85 |
2.64 |
2.47 |
2.31 |
2.18 |
2.06 |
1.95 |
1.85 |
| 36 |
3.6 |
3.27 |
3 |
2.77 |
2.57 |
2.4 |
2.25 |
2.12 |
2 |
1.89 |
1.8 |
| 35 |
3.5 |
3.18 |
2.92 |
2.69 |
2.5 |
2.33 |
2.19 |
2.06 |
1.94 |
1.84 |
1.75 |
| 34 |
3.4 |
3.09 |
2.83 |
2.62 |
2.43 |
2.27 |
2.13 |
2 |
1.89 |
1.79 |
1.7 |
| 33 |
3.3 |
3 |
2.75 |
2.54 |
2.36 |
2.2 |
2.06 |
1.94 |
1.83 |
1.74 |
1.65 |
| 32 |
3.2 |
2.91 |
2.67 |
2.46 |
2.29 |
2.13 |
2 |
1.88 |
1.78 |
1.68 |
1.6 |
| 31 |
3.1 |
2.82 |
2.58 |
2.38 |
2.21 |
2.07 |
1.94 |
1.82 |
1.72 |
1.63 |
1.55 |
| 30 |
3 |
2.73 |
2.5 |
2.31 |
2.14 |
2 |
1.88 |
1.76 |
1.67 |
1.58 |
1.5 |
| 29 |
2.9 |
2.64 |
2.42 |
2.23 |
2.07 |
1.93 |
1.81 |
1.71 |
1.61 |
1.53 |
1.45 |
| 28 |
2.8 |
2.55 |
2.33 |
2.15 |
2 |
1.87 |
1.75 |
1.65 |
1.56 |
1.47 |
1.4 |
| 27 |
2.7 |
2.45 |
2.25 |
2.08 |
1.93 |
1.8 |
1.69 |
1.59 |
1.5 |
1.42 |
1.35 |
| 26 |
2.6 |
2.36 |
2.17 |
2 |
1.86 |
1.73 |
1.63 |
1.53 |
1.44 |
1.37 |
1.3 |
| 25 |
2.5 |
2.27 |
2.08 |
1.92 |
1.79 |
1.67 |
1.56 |
1.47 |
1.39 |
1.32 |
1.25 |
| 24 |
2.4 |
2.18 |
2 |
1.85 |
1.71 |
1.6 |
1.5 |
1.41 |
1.33 |
1.26 |
1.2 |
| 23 |
2.3 |
2.09 |
1.92 |
1.77 |
1.64 |
1.53 |
1.44 |
1.35 |
1.28 |
1.21 |
1.15 |
| 22 |
2.2 |
2 |
1.83 |
1.69 |
1.57 |
1.47 |
1.38 |
1.29 |
1.22 |
1.16 |
1.1 |
| 21 |
2.1 |
1.91 |
1.75 |
1.62 |
1.5 |
1.4 |
1.31 |
1.24 |
1.17 |
1.11 |
1.05 |
| 20 |
2 |
1.82 |
1.67 |
1.54 |
1.43 |
1.33 |
1.25 |
1.18 |
1.11 |
1.05 |
1 |
|
The stock gearing of your bike is likely
to have been determined by choosing a
compromise ratio based on what worked
best for test riders in "average"
conditions.
As soon as the bike is taken out of average
conditions - by engine tune, terrain,
track design or rider style the stock
gearing might no longer be the optimum
solution - a different setup might get
you round the track faster.
Maximum speed occurs when the driving
force is exactly counterbalanced by the
air and rolling resistances. At this point
the acceleration has fallen to zero.
Setting up the gearing of any vehicle
is a trade-off between acceleration and
top speed.
Gearing a bike up to produce higher top
speed with less acceleration is done using
a larger countershaft (gearbox) sprocket
or a smaller rear sprocket.
Gearing a bike down giving it more acceleration
with lower top speed is done using a smaller
countershaft (gearbox) sprocket or a larger
rear sprocket.
The ratio chart shows the gearing ratios
for different numbers of teeth on the
gearbox and rear sprockets.
The numbers given are the number of revolutions
of the gearbox sprocket required to cause
one complete revolution of the back wheel.
These figures are calculated by dividing
the number of teeth on the rear sprocket
by the number of teeth on the gearbox
sprocket.
From the table it is clear that changing
one tooth on the gearbox sprocket has
a significantly larger effect on the gearing
than changing one tooth on the rear sprocket.
To make a small change in gearing it is
therefore necessary to change the rear
sprocket size by one tooth, as changing
the gearbox sprocket makes a far larger
difference in gearing. |
