When sizing a bike it is helpful to understand that you are not just buying a bike off the floor in your size and all will be OK . For the bike to feel as an extension of yourself we may need to make changes to your ride position. Altering the seat and handlebar will make the bike feel totally different. There is no absolute correct ride position for everybody as position is very individual. The guidelines to fitting a road bike usually requires precise fitting because you are in one position for long time, with considerations of breathing, aerodynamics and comfort, whereas an MTB covers extreme variation in terrain and the rider is in a multitude of riding positions, therefore the concerns are comfort and handling, not aerodynamics.
When purchasing a bike from bikeNOW, you do not need to worry about fitting. As part of our sales service, we will correctly fit you to your bike, testing variations until you are happy with your ride position.
Seat to crank relationship.
Your knee should have a 5 to 10 degree bend at full leg extension with your ankle relaxed (See figure 1 (a)). Some riders choose to ride a slightly lower seat height however riding at a higher height can be harmful.
You may achieve the correct seat height on 2 or 3 different frame sizes therefore the seat height may not determine the ideal size bike for you. A way to estimate your seat height fairly accurately is to measure your maximum inseam with your cycling shoes on and multiply the measurement by 0.883. Apply this length to the centre of your cranks and your seat. (See figure 5). You can check for accuracy making sure you are able to pedal with your heels on the pedals without pelvic rotation.
Centre weight balance.
After we have your seat height correct and before we work on your handle bar position it is a great idea to see where your centre of balance is. We don’t want too much weight on your handlebars. While your cranks are in a level position (9 & 3 o’clock) we run a vertical line from the bump below your kneecap, we then adjust your seat forward or back until the line runs through the pedal spindle. If you are too far forward it puts more weight on the handlebar however makes the bike a bit better for sprinting (road use) or gives you more room to move back over the seat on rough terrain (MTB use). Back a bit can make the bike feel a bit more relaxed on longer rides and take weight of the bars however your upper leg will need to work harder on climbs. (figure 6). 
Handle Bar to seat relationship.
This is the part that is entirely up to you. Try different positions until you find a back angle that feels comfortable. (See figure 1 (b)). Our fitting staff have ways of measuring handle bar position to suit the type of riding you will be doing from free-ride jumping to triathlon however it is ultimately you that determines the fit.
The handle bar assembly can be adjusted in both directions and/or replaced to fine tune your position (See figure 1 (c)). We can offer a 90mm to 130mm stem length without affecting the handling characteristics of the bike too much however if you require a length outside this parameter we may look at a different size bike. This suggests that the frame length determines the ideal size frame that will suit you not the stand over height. A higher and closer handle bar position is more preferred by recreational riders whereas a lower position is preferred for performance.
Bike sizing computers give only a guide to sizing and the frame sizes vary between each manufacturer. Each rider has different preferred riding positions and ultimately the choice must be made by what feels comfortable to you!
Many riders complain about a sore neck. If your seat position is correct it you will be trying to shorten the head stem or raise the handle bars. There are different riding techniques that will help you transfer some load to your arms not your neck and shoulders by doing a small exercise;
This page is a brief overview on positioning.
Click here to go to our Bike Sizing and Fitting Guide.
