Paul Hewitt Cycles - The Specialists

Saddle height.

This is usually measured from the centre of the bottom bracket along the line of the seat tube to the top of the saddle.
When performing the fitting it is generally best to use the crank length, pedals, saddle, shoes and shorts that you intend to use on the completed bicycle. If a different saddle is used then the saddle height could be inaccurate as different saddles may have different densities and thickness of padding meaning that you could potentially sink into the saddle more or less than the saddle you end up using, thus throwing the saddle height out.
The same is true of the pedals, different pedals could have a different stack height to them and the shoes could have a different thickness to the sole and to a lesser degree the thickness of the padding in the shorts could also vary slightly.

Means of adjusting saddle height.

The saddle height is normally adjusted by slackening off the seat pin bolt and raising or lowering the seat post, more recently some frames (usually the more expensive models in the range) are designed with an integrated seat post, on this style of frame the seat tube has to be cut in order to set the saddle height. It is obviously best in this instance to know the saddle height first.

What can affect saddle height.

The only body dimension that affects saddle height is the inside leg dimension, as mentioned above it is best when determining the saddle height to use the crank length pedals, saddle, shoes and shorts that you intend to use on the completed bicycle. Having said this if ever any of these items are subsequently changed then the saddle height may need adjusting.

Saddle Set Back.

Saddle set back is the horizontal dimension between the centre of the bottom bracket and the nose of the saddle, this is sometimes measured to the rear of the saddle or in some cases a certain dimension along the saddle, if the saddle that you are using on the bike is the same as on the jig the all these ways of measuring saddle set back will be just as accurate.

Essentially the ideal measurement would be from the position on the saddle where the sit bones are, but as this is near impossible to determine, it is easier to use the same saddle for the fitting as you intend to use on the completed bike, so that sit bone position relative to the nose of the saddle will be the same.

Means of adjusting saddle set back.

The saddle set back is normally adjusted by slackening off the seat clamp bolt or bolts and the sliding the saddle forwards or backwards to set the desired saddle set back,  due to the angle of the saddle rails it may be worth checking, and if necessary re-adjust the saddle height.

If the saddle set back cannot be achieved with your current seat post it may be possible to obtain another seat post with more or less set back on the post in order for you to obtain the required saddle set back.

What can affect saddle set back.

The only body dimension that directly effects the saddle set back is your thigh length, the longer your thigh (relative to inside leg) then the further back the saddle would need to go, the shorter the thigh (relative to inside leg) and the forward the saddle would need to be.

Relative height of the bars and saddle.

This is also known as bar drop. The best way to measure this is to measure from the floor to the top of the saddle, subtract from this the dimension from the floor to the top of the bars, the bars are normally lower than the saddle although this is not always the case as smaller riders with shorter arms will need the bars much higher (relative to the saddle) than a taller person with longer arms.

Means of adjusting bar height.

Most current frames have an A-Headset system fitted, the height of the bars can be adjusted – assuming there is sufficient fork column to do so – by moving spacers from below the stem and placing on top of the stem in order to lower the bars and the opposite to raise the bars. Once the bar height has been set the excess fork column is generally cut to length, it is usually best to leave 5mm or so on top of the stem so that the stem clamps across its full height. It is generally recommended that on carbon fork columns that the spacing under the stem does not exceed the diameter of the fork column, ie. 25mm maximum spacing on a 1″ steerer and 30mm spacing on a 1 1/8″ steerer.

Once the steerer has been cut then the stem would not be able to be raised higher than the top of the steerer, the stem could always be flipped to make use of the angle on the stem, this would usually alter the height, although this difference would be dependant on the angle and length of the stem, it is usually approximately 20mm or so on a mid length 6 or 10 degree angled stem.

If the fork column has been cut too short and the steerer is steel or aluminium then it is possible to fit an A-head extender which will possibly allow you to set the bars at the correct height, these use an expander bolt securing system which not recommended for carbon steerers.

What can affect the bar drop?

The bar drop required is mainly dependant on two things, your arm length and your flexibility. The longer your arms the lower the bars can be relative to the saddle, if you have shorter arms then the bars will need to be higher relative to the saddle, even to the extent that the bars may end up higher than the saddle. Again the more flexible you are the lower the bars could be but never to the extent that the comfort is compromised.

For shorter people with shorter arms it may also be worth considering using a compact style handlebar. These are a fairly recent addition to the more usual anatomic handlebars, compact bars are bars with less of a drop down to the drops of the bar and they generally have a shorter forward reach, although the exact dimensions vary from bar to bar. The result of using these compact style bars is that the various hand positions on the bars are less extreme.

Reach – (from saddle to bars)

This is the last of the main four position dimensions and is the dimension from the nose of the saddle to the centre on top of the bars, usually measured directly, rather than horizontally.

Means of adjusting the reach.

The only way of adjusting the reach is by altering the stem length, although once you know what reach you require it is a fairly straight forward task of working out what stem length would be required in order to obtain your required reach.

What can affect the reach?

The reach is dependant on your own arm length – mainly forearm – and your torso length. The longer the arm, forearm and torso length, the longer the reach needs to be.