Adjusting road and gravel bikes to tailor the fit. Some tips and what to be aware of.
The starting point for achieving a good position on any road bike is the frame size. Too big or too small a frame can limit the opportunity to adjust and tailor the fit to the individual. Also, the wrong frame size can compromise handling too. Remember the bike fitter’s mantra, the best time to get a bike fit is before buying a bike.
Let’s consider that we have the right sized frame and we want to start adjusting it for the individual rider. What options do we have?
We should start with the saddle position first as this creates an efficient, balanced, stable base to pedal on. It can also prevent many issues arising that people might wrongly associate with the stem and bars or ‘cockpit’ such as numb hands or back ache.
Correct Saddle Height
The correct saddle height can be achieved by raising or lowering the seatpost in the frame. The exception to this is if you have an integrated seat mast. In which case adjustment is limited by your nerve to cut the mast to size. Mast height can be fine-tuned by a few millimetres using packers.
If you need to increase your saddle height, make sure you observe the maximum height limit. It is often marked on the seatpost or any advice given by the frame manufacturer about how much seatpost must remain inside the seat tube. If your bike utilises a simple round seatpost, it is possible to buy longer seatposts to increase saddle height. It is also possible to cut seatposts down that are too long. This can stop the saddle dropping lower if it fouls on bottle cage rivet nuts or tapered seat tubes. Be aware of the safety issues of cutting carbon seatposts. Not just the integrity of the post but the danger from the dust particles released when cutting. Wear a mask, dampen the cutting area and perform the operation outdoors. They also require a carbon specific saw blade.
Saddle Position
The fore and aft of the saddle position can be adjusted by moving the saddle backwards and forwards on its rails. Some saddles, such as Selle SMP, are renowned for having long rails. These can help with positioning by increasing the range of available movement. The goal though is to really have the saddle centred on its rails. The reason is that this can help with saddle comfort. The rails can absorb vibration better. Also, it reduces the risk of damage as a saddle pushed all the way forward or back has a lot of cantilever force being applied to it that can lead to material fatigue.
So, as well as using the saddle rails, the amount of layback a post has can differ. A typical layback is 20mm but to bring the saddle forward a zero setback seatpost can be used, and to get further back, 40mm of setback can be found. Again, aftermarket seatposts that can help with this are generally round, so you might be out of luck if you’ve a modern frame with a profiled post. The use of the word’s setback, layback and offset can all be interchanged. As with all bike fit adjustments, we’re only moving 2-3 millimetres at a time as it is possible to miss the sweet spot with too big an adjustment.
Adjustments
The last bit of adjustment (saddle make and model aside) available is the tilt. Generally, saddles are designed to be flat. That, however, is a hard position to establish given the profiles of some saddles. Consider the S shaped curvature of a Selle SMP saddle, whereabouts is the level bit that you sit on? I find it easier to just consider the position relative to a previous position i.e. nose up or down. I use a piece of wood along the saddle’s length and a digital angle finder to note the final position. Also remember the angle is relative to the surface that the bike is stood on, is that level too?
I typically find that a slight drop to the saddle tilt is beneficial, particularly for female cyclists. Be careful of going too low. This will place weight on your hands and lead to an unstable, falling forward sensation. Particularly noticeable on long mountain descents where your arms may tire.
Feet Adjustments
Let’s move lower down the bike and consider how we can adjust where our feet are. If you are using clipless pedals they can be adjusted to suit an individual’s needs. Cleats can be adjusted laterally to increase and decrease the stance width or Q factor. They can also be moved backwards and forwards and rotationally too. All these movements alter pedalling characteristics, balance point and cycling comfort.
The width of the cyclist’s stance can be further adjusted by adding spacers between the pedal and crank arm. Care must be taken to ensure that there is enough pedal thread left in the crank arm to prevent it stripping and falling off. It is also possible to buy pedals with different axle lengths to increase the amount of adjustment.
Another way to tailor a bike is through fitting a chainset or crank with a different length arm. Crank length tends to be proportional to leg length with shorter cyclists benefitting from a smaller arm length. Whilst taller riders don’t really notice so much. The exception to this is for aggressive aerodynamic positions such at Time Trial (TT) or Triathlon (Tri) bikes where the upper body is extremely low and a long crankset can inhibit the cyclists from smoothly getting the crank over the top of the pedal stroke in a cramped space.
Cockpit Area Adjustments
Now let’s move forward and up to the cockpit area. Here we can start making a difference to the stack (height) and reach (fore and aft position) of the handlebar. Most new bikes come with spacers under the stem that can be removed to lower the bar height. Typically, you might find 30-40 millimetres of spacers and they are often found in 3, 5, 10 and 20 millimetre heights enabling a fine tuning of height. When removing spacers from below the stem they can be put above the stem to enable the preload of the headset bearings to be adjusted. Often people like to cut them down when they’re happy with the height.
Bear in mind if you don’t cut the steerer on your forks down that you must ensure that the compression bung inside the steerer is long enough to drop down inside and support the clamping area of the stem. Too short, and if the fork has a carbon fibre steerer, the stem can squash the steerer potentially leading to the headset working loose, or even worse, the steerer tube fracturing. Just consider the recent Canyon Speedmax recall and the solution is to fit a longer compression bung to support the inside of the steerer.
Correct Angles
One of the things often overlooked is that lowering the stem can lead to the reach becoming longer. This is because head angles of bikes aren’t 90° and don’t move up and down in a straight line. I use this handy online tool to visualise the difference changes can make. Consider a typical 100mmm stem with a negative 6° angle, when removing 40mm of spacers. The bar position actually increases in reach by 11 millimetres.
Stems can help us adjust both height and reach. Stems are available in many different lengths that help tailor the reach. Typically, road bike stems come in lengths ranging between 60 and 130mm and bike manufacturers tailor the length to work best with their frame design (and size, proportionality again) to give the desired handling characteristics. A shorter stem can make a bike steer quicker and become twitchy and a longer one vice versa.
Most stock road stems come in a negative 6, 7 or 8° rise but can be flipped over to increase height. In the example below, flipping a 6° 100mm stem results in 20mm of height increase, also note again how the reach has change, it’s shortened by 6mm.
Stems
As well as flipping stems and altering the number of spacers below them, aftermarket stems also come in many different rises. This can be useful in adjusting bar position. Need a lower position look at stems like the Deda Pista with a negative 20° negative angle. Higher rises tend to jump up in 17 and 35° positive angles from the stock 6,7, and 8° standard.
We’re now onto the final component that we can swap out, the bar, and boy are there lots of things to consider here. I’m still primarily considering drop bar bikes such as road and gravel.
Number 1, Width
Things to note here are that it’s always worth checking to see how manufacturers measure their own product. Deda measure outside to outside of the handlebar tubing whilst Pro measure centre to centre. It’s always best to try and find a schematic drawing to know for sure what width is being referred to. A 40 cm Deda can be two cm shorter than a 40cm Pro. Most bars are measured across the top width.
Number 2, Flare (increasing width at the drops)
It used to be common for road bars to have the same width top and bottom. Nowadays you might find a little bit of flare on road bars so that the drops are 2-3cm wider helping stability. Gravel bars can come with huge flares up to 30° increasing the width greatly in the drops apparently increasing stability over bumpy off-road sections. Note the flare of the bars will cause shifters to rotate too and can make how they sit in the hand more or less comfy. Using the brakes can become more difficult depending on where you like to place your hands when you ride.
Number 3, Sweep
This is something of a newer adjustment on drop bars. On older bars the top section comes out at 90° from the stem until it turned forward for the extension to the shifter hoods. Sweep is the angle that the top section now comes back towards the rider. That is the centre of the bar is further from the cyclist than the ends of the bar so it can reduce reach. Sweep can help with wrist comfort creating a more natural angle for the hand gripping the bar when on the tops.
Number 4, Forward Extension
Again, another parameter that adjusts the reach to the hoods. Not all bars have the same length from where the bar curves forward towards the shifter hoods and where it turns down to become the drop. A longer extension can help cyclists who require more reach or who have bigger hands and want more room. Foe riders that like to lean forward with their forearm on the extension to gain a more aerodynamic position a longer extension can help.
Number 5, Bar Rise
As with sweep, it’s a recent addition to drop bar configuration. I think we can thank gravel riding for both. If you need extra bar stack and you have all the spacers below the stem but don’t like the aesthetics of a positive angled stem. Then maybe bar rise can help. I like the Genetic Driser4 that gives 20mm of height. Other brands and models can have more or less rise. Where the bar rises can reduce the top section space so something to consider if you like using that a lot for climbing.
I think I’ve covered above all the main items that can be adjusted to help tweak a frame and bike fit to the rider. I count 6 components and 13 design configurations, that ultimately move the seating and hand position up, down, backwards and forwards. Hopefully it’s useful to list them all out. If you would like any help setting your bike up to suit you, please consider booking a bike fit with me where we can test these factors out and see what works best for you. It might save you some money to do this in advance before purchasing the wrong part or indeed frame.
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Scott
fitmybike.co.uk