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Questions and answers about sports

Top tube angle on steel and carbon road bikes

6 min read

Asked by: Rebecca Walker

How does head tube angle affect handling?

In simple terms, head tube angle dictates how much effort is required to turn the front wheel. As head angle increases, the front wheel becomes easier to turn. It is also possible to make a sharper turn, and thus, the manoeuvrability of the bike generally increases with the angle of the head tube.

Why are top tubes sloping?

The reason given by the manufacturers was that by sloping the top tube, and therefore taking standover clearance off the table as a fit element, it was now possible to fit more riders on fewer sized frames. (It did not go unnoticed by the skeptics that it also greatly reduces the inventory burden of the manufacturer.)

How do you measure the angle of a top tube?

Align the top edge of the level with the centreline of the top of the head tube. Then move the level back and forward until the plumb line intersects with the centre of the bottom bracket spindle. Now just measure the distance between the top of the plumb line and the head tube and you’ve got your reach.

What does a steep head tube angle do to the way a bike rides?

The steeper the head tube angle, the better handling you’ll achieve, but with less stability at speed. Most trail bikes have settled on a minute range of somewhere between 65 and 67 degrees. Downhill bikes will have angles anywhere from 62 to 64.

How much of a difference does head tube angle make?

When the head angle is steeper, the bike becomes more nimble and twitchy. The bike reacts faster to steering input making it prone to oversteer. Road bikes tend to have “steep” head angles in the 72 to 74 degree range. A half degree is more noticeable on bikes with steeper head angles, especially at higher speeds.

Does head tube angle affect reach?

That’s because the head angle is not vertical – so, the longer the head tube, the further back the top of it becomes, and so the shorter the reach measurement.

What makes a road bike aggressive?

Broadly speaking, road bikes can be grouped into two geometry categories: race and endurance. A race bike will have a more aggressive geometry for improved aerodynamics, while a bike with an endurance geometry (or ‘sportive’ geometry) will be shaped for comfort, with a more upright riding position.

Does bike geometry affect speed?

The short answer is that ‘it depends‘. Some viewers commented that maybe it just doesn’t matter. It absolutely does matter and indeed the geometry of the bike is the most powerful way that we can change the riders experience of the bike.

How long should my top tube be?

The most important consideration to make as you decide which frame to go for is the effective top tube length: the distance from the head tube to the seatpost on a bike with a sloping top tube, or simply the length of the top tube on a road bike with traditional geometry.

Is a 67 degree head angle slack?

That’s a slack head angle. 65-ish is for Dh race bikes. 67-ish is ‘normal’. 70-ish is a road bike*.

How does seat tube angle affect ride?

Seat tube angles range from about 70-75 degrees. A steeper angle moves the saddle forward while a shallower angle moves it back. Steep is fine for racers. It allows them to ride hard in an aero crouch, as the more open hip angle doesn’t constrain breathing or power transfer.

How do you measure a top tube on a road bike?


Quote from video: Now if you've got a frame of a horizontal top tube and the seat tube measurement is simply taken from the center of the bottom bracket.

What is aggressive bike geometry?

Aggressive geometry puts your upper body down lower for aerodynamics and the bikes tend to favor a more twitchy handling traits. Relaxed geometry has you sitting in a more upright position and the bike is setup to feel more stable at speed.

How does fork rake affect handling?

Fork Rake and Offset



The amount that the fork is offset from this imaginary line is known as fork rake in road bikes, or fork offset in mountain bikes. Increasing the offset will make steering faster, conversely decreasing it will slow it down.

What angle should bike seat be?

The correct saddle angle is much more important than most cyclists realize. For example, lower back pains are a common issue for cyclists, and an incorrect saddle angle is often (part of) the problem. The guideline for the angle of your saddle is between 0 degrees (horizontal) and 4 degrees nose down.

How does seat tube angle affect ride?

Seat tube angles range from about 70-75 degrees. A steeper angle moves the saddle forward while a shallower angle moves it back. Steep is fine for racers. It allows them to ride hard in an aero crouch, as the more open hip angle doesn’t constrain breathing or power transfer.

How does head tube angle affect handling BMX?

The angle of the headtube determines how steep or mellow your bike feels. A 76º headtube angle will make the front wheel closer to your feet. This, in turn, gives your bike a more snappy and responsive feeling. Making steering and nose manuals really responsive.

How does fork offset affect handling?

By reducing the fork rake (offset), the head angle remains the same for stability at high speed and down steep and rough trails, but the wheel is closer to the steering axis for better handling, especially at slower speeds.

How much does fork travel affect head angle?

Bumping the fork travel up by 20mm, to 150mm, will slacken the head angle by approximately 1° and increase the front centre measurement by 10mm.

Is a 67 degree head angle slack?

That’s a slack head angle. 65-ish is for Dh race bikes. 67-ish is ‘normal’. 70-ish is a road bike*.

Is 150 mm too much travel?

Those roots and rocks can ping you offline, despite being sure of your steering inputs. Too much travel can also dull the feedback of your trail bike. We recommend that a trail fork ideally have 34mm stanchions, at 130-140mm, for a 29er – possibly, up to 150mm, for the smaller 27.5in wheel size.