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Sizing - Road Bikes.
Using the traditional method 9 to 10 inches is deducted from the inside leg
measurement taken in stocking feet (NB This is not the same, as the
dimension quoted against "Inside leg", on the label in your trousers!). For example an inside leg measurement of
30 inches would have 9 or 10 inches deducted so a frame of 20 or 21 inches
would be recommended.10 inches would be deducted, when the seat tube finishes
level with the top tube and is measured to this point. 9 inches would be
deducted, when the seat tube extends above the top tube by an inch or so as it
does with current aluminium frames.
As a very rough guide the following sizes apply:-
HEIGHT
FRAME SIZE
5 ft 3 ins to 5 ft 5 ins
19 to 20 inch
5 ft 5 ins to 5 ft 7 ins
20 to 21 inch
5 ft 7 ins to 5 ft 9 ins
21 to 22 inch
5 ft 9 ins to 5 ft 11 ins
22 to 23 inch
5 ft 11 ins to 6 ft 1 in & over
23 to 24 inch
6 ft 1 in & over
24 to 25 inch
Sizing A.T.B.
An additional 3 to 4 inches are deducted from the above figures for ATB frames
Positioning.
Saddle Height.
Set one crank vertical so that the pedal is in the lowest position, then place
the shoed heel of your foot on that pedal. The saddle should be adjusted up or
down till there is a slight bend at the knee. It should be possible to place
both heels on the pedals and pedal backwards without rocking from side to side
on the saddle.
NB Knee problems may be caused by having a top of saddle to pedal dimension of
more than 110 % of the rider’s inside leg measurement.
Saddle Lateral Position.
Set the cranks horizontal, while sitting properly on the saddle, then place
one shoed foot on the forward pedal so that the ball of that foot is on the
pedal spindle centre line. A plumb line held just behind the knee cap should
pass through the pedal spindle centre line. The saddle should be loosened &
moved backwards or forwards to achieve this position. The top of the saddle
should always remain horizontal. This check must be carried out on a level
surface. This represents the best position for riding on flat roads. Easing
forward in the saddle when going uphill & backwards when going downhill is
possible & gives the rider an acceptable level of stability.
Handlebars (Road Bikes).
The stem needs to place the handlebars 1 to 2 inches below the top of the
saddle & 1 to 2 inches plus the forearm with extended fingers from the nose of
the saddle. To do this place the elbow against the nose of the saddle & extend
the forearm & fingers parallel to the top tube towards the handlebars. A gap
of between 1 & 2 inches should exist between your fingers & the handlebar. 1
inch gives a general riding position & 2 inches a more competitive position.
The position you have achieved is a good starting point.
Tourists tend to sit further back, lower down & with the handlebars up a
little.
Sprinters generally sit higher & further forward with handlebars down a bit.
If you suffer from a "Bad back", it is usually necessary to
sit in a more upright position would normally be the case. Therefore the
handlebars would tend to be higher and/or further back.
Handlebars (A.T.B.).
For general riding, a position where the handlebar grips are placed 1 inch
below the top of the saddle & 1 inch in front of the extended fingers suits
most people. See section above for Road Bike Handlebars for details.
Copyright © 2004 Nelson Cycles and Engineering.