Landevejsgeometri forklaret: din ultimative guide til rammedesign

A bike’s geometry ultimately determines both its size and how it handles on the road. Bike geometry can be a bit complicated, but we’ll try to make it as easy to understand as possible, while comparing the different types of bikes Canyon offers, from race bicycles to endurance machines to gravel bikes.  

Bike geometry is one of the simplest ways to understand how any drop-bar bike will fit and feel. Whether the frame is built for smooth roads or rougher gravel, the core measurements work in the same way and influence the same things: comfort, stability, and handling. In this guide, we break down the key terms, explain why they matter, and show how to use them to choose the right size and setup. 

Think of it as a straightforward primer on the numbers that shape every modern road and gravel bike. 

The size of the frame determines how they handle; bigger frames handle differently to smaller frames. Frame size also subtly affects geometry as well. Due to longer tubes, a larger bike frame may be slightly less rigid than a smaller frame. While this means a less-efficient power transfer, that small flex increases comfort over longer distances.

Smaller frames also leave less room around the front wheel, so certain adjustments to the front end are needed to maintain consistent riding dynamics across all sizes. These changes make sure the bike still steers naturally and feels predictable on the road or gravel, regardless of size.

For years, stack and reach have been the go-to numbers for comparing frame fit. Stack measures the vertical height from the bottom bracket to the top of the head tube, while reach measures the horizontal distance. Together, they give a rough idea of how stretched out or upright a bike will feel. Useful? Yes. Complete? Not quite.

Stack and reach tell you where the frame ends – not where you actually hold the bars. And that’s the really important part. That’s why two bikes with similar stack and reach measurements can still feel totally different once you actually start riding them.

To give you a true sense of real-world fit, we’ve created effective stack and reach – measurements based on where your hands actually grip the bars. By starting from your real contact point, they give a clearer picture of how the bike will feel when you’re riding, not just how the frame is shaped.

Effective stack and reach factor in the cockpit shape, stem length, and the spacers the bike ships with. The result: numbers that translate directly into how the bike feels when you ride it.

Effective stack is the vertical distance between the bottom bracket and your hood position, essentially how high the front of the bike feels when your hands are on the bars. You notice it straight away: a higher effective stack puts you in a more upright, relaxed posture, while a lower one drops your torso for a flatter, faster position.

When comparing road bikes, more race-focused bikes sit lower, like the Aeroad at 642 mm (size M), putting you in a properly low, slammed aero position. Comfort-focused endurance bikes sit higher, with the Endurace at 675 mm (size M) lifting the front end for a more relaxed fit for longer rides.

Effective reach is the horizontal distance between the bottom bracket and your hood position. It tells you how far you reach to the bars and how stretched or compact your riding position feels. A longer effective reach puts you in a more extended posture, while a shorter one brings the bars closer for a steadier, more upright feel.

When comparing road bikes, more race-focused setups run a longer reach, like the Aeroad at 563 mm (size M), giving you that flat, fast position riders look for when chasing maximum aero. Comfort-focused bikes sit shorter, with the Endurace CFR and CF SLX at 547 mm (size M), bringing the front end in slightly for a more upright all-day fit.

For gravel bikes, the numbers shift again. The Grizl sits at 544 mm (size M), shorter still, putting you in an even more upright position for maximum confidence over rough and unpredictable terrain.

Although effective stack and reach may be the two most important measurements to take into account when buying or fitting a bike, there are several other geometry measurements to consider as well.

Standover height

Standover height is important when purchasing your ideal size bike because you need to be able to put two feet on the ground when stopped. (It’s not going to feel comfortable if you’re on tip-toes at every stoplight!) To get the road bike’s standover height, measure from the midpoint of the top tube to the ground.

Seat tube length

The distance between the center of the bottom bracket and the top of the seat tube, seat-tube length indicates how much of your seat post will be exposed when setting the bike up.

Oddly enough, the amount of seatpost exposed actually affects your bike’s ride. Very little seatpost exposed means the road bike generally feels stiffer to ride. If you have a lot of seatpost exposure, you’ll notice more flex and a more comfortable ride.

Head tube angle

The head tube angle – the angle at which the front wheel sits relative to your head tube – helps determine a bike's stability. If the front wheel of a bike sits further forward, then the wheelbase will be longer, and the bike will usually be much more stable at high speeds. 

This measurement is one of the more important aspects of mountain bike geometry.

What do slack and steep mean?

Comparing the Aeroad, our Monument-winning speed bike, and the Grizl, the differences are clear to see. The medium Aeroad has a fairly steep 73.25-degree head angle. This gives the bike fast handling that elite road racers demand. The Grizl is designed for long gravel rides with a slacker, 71-degree head angle. This makes the steering a little slower to help you feel more confident on rough ground. A slacker head angle will also make the front of the bike a touch longer, which helps the stability (road bike geometry guide).

Seat tube angle

The seat tube angle is measured from the horizontal to the tube. This angle dictates the degree to which you ride over the pedals and bottom bracket. A steeper seat tube angle means you ride more over the pedals, which is generally preferred by road racers, time-trialists and triathletes.

It encourages a lower position on the road bike and prevents stress on the thigh muscles over long periods. A slacker seat tube angle is a bit less efficient, but more comfortable.

Canyon road bikes use a balanced seat angle of 73.5°, which puts you in a balanced position in the center of the bike – great both on the flats and on climbs. In contrast, the Canyon Speedmax triathlon bike has an extremely steep 80.5° seat angle to put you in a very aggressive aero position over or almost in front of the bottom bracket. 

Seat height

Seat height is one of the first checks when it comes to sizing. If you cannot set the saddle where you need it, the bike will never feel right. Your available range depends on the frame’s seat tube and the seatpost’s design, which together decide how much room you have to dial in a comfortable, efficient pedalling position.

Wheelbase

The wheelbase is the distance between the hubs of both wheels. The longer the wheelbase, the more stable the ride. For example, with a wheelbase of 1003 mm (size L), the Canyon Ultimate produces a snappier, more responsive ride than the Canyon Grizl gravel bike, which has a much longer wheelbase of 1050 mm (size L) to boost stability over rough terrain.

Chainstay length

Chainstay length is closely linked to the overall wheelbase of a road bike. Race bikes typically feature shorter chainstays to keep the handling agile and reactive. The Endurace, which prizes comfort and stability on the road, has a slightly longer chainstay, 415 mm (size L) than the Ultimate’s 413 mm; 2 mm difference may seem like a minute amount, but you can feel the difference on the bike.

Bottom bracket offset

The bottom bracket offset is the distance between the horizontal line of the bottom bracket and the horizontal line between the wheel hubs. Sometimes referred to as the “bottom bracket drop,” this particular measurement helps determine a bike's stability. A bigger offset means the bike has a lower center of gravity.

Gravel bikes tend to be a little lower than road bikes - the Grail and Grizl both have 75 mm bottom bracket offsets, while the Aeroad has a 70 mm offset. This makes the Grizl and the Grail a little more stable than the Aeroad.

Tyre clearance

Tyre clearance should be an important consideration for anyone buying a road or gravel bike, telling you not only which tires are compatible with your bike's frame and fork, but also giving you an insight into its capabilities. A bike with wider tire clearance will be suitable for more off-road pursuits compared to one with narrower clearance. Wider tires increase comfort, but also increase the rolling resistance, so you'll need to find your ideal balance.

How it works on road bikes

Years ago, most experts thought the skinnier the road bike tire, the better. Many pros rode on 19 mm skinnies for their entire career. But between research pointing toward wider tires being better and technological advancements like disc brakes, the most prevalent widths in our range are now between 28-32 mm.

How it works on gravel bikes

Gravel frames are built for bigger tyres, and the numbers tell the story. The Grail clears 42 mm – wide enough for real grip, fast enough for race pace, and dialled for that sweet balance of speed and control. The adventure-ready Grizl gives you a boosted 54 mm of clearance for chunky, near-MTB rubber. More volume, more bite, more confidence when the terrain gets wild.

Top tube length

Because of this, top tube length has largely been replaced by effective stack and effective reach as the most reliable indicators of real-world fit and position.

Head tube length

Head tube length feeds directly into a bike’s stack measurement. A shorter head tube lowers the front of the bike, giving you a flatter, more tucked position, while a longer head tube raises the front end for a more upright, relaxed posture.

Just like top tube length, head tube length matters far less on modern bikes when it comes to choosing the right size. Because it only describes the frame and not your true hand position, effective stack now provides a much clearer and more reliable picture of how high the front of the bike will feel when you are actually riding.

Some parts of a bike’s handling come from measurements you will not find on a standard geometry chart, but they still have a big influence on how the bike feels when you ride it.

Fork rake

Fork rake is the distance between the fork blades and the steering axis, measured at the front axle. More rake pushes the front wheel further forward and gives the steering a quicker, lighter touch. Less rake keeps the wheel closer in, increasing trail (see below) and adding stability when the speed picks up. It’s one of the key ways designers tune a bike to feel sharper or more settled at the bars.

Trail

Trail is the distance between where your front tyre touches the ground and where the steering axis would meet the ground if it continued downward. In simple terms, it shows how far the contact patch “follows” behind the steering axis. More trail gives the bike a calmer, more planted feel at speed. Less trail makes the front end quicker and more agile. Together with fork rake, it sets the balance between stability and a more lively, responsive ride.