It’s expected that an upcoming fork for 32″ wheel is going to have a 1.5° angle of slider to steerer. This isn’t common in bicycles or motorcycles. Typically, the slider plane is aligned with the head axis.
It does happen. Some chopper motorcycles do this. Recently, gravel forks produced by several top suppliers have used sliders planes set at an angle to the head axis. I write about that in the following post.
In that post, I discuss the geometric concerns for using this method in a bike design. How do we ensure our geometry is what we say it is when it’s being planned and constructed? This was relatively straightforward.
The question arises, what does this produce in the system and why would we implement it? In the case of the gravel forks, it’s clearly being done to clean up the visual aesthetic of the fork to make it more palatable for the consumer. Having an inline connection of the axle to the slider significantly cleans up the look of things and may make the low travel system a little lighter.
Now, we are coming up to a new situation. A fork that looks like any other mountain bike fork but has an angled slider. The essential architecture of the fork is otherwise identical to those slider plane is aligned to the head axis. Why would this choice be made?
I did some calculations based on my upcoming MTB-LT, the Warthog. So that it is clear what values may have been used in my calculations, I’ll include a print of that bike design.
I can gain some understanding of what happens with the front end and crank axis by doing some basic math. The entirety of the bike’s geometry was used to do these calculations to ensure precise representation. Honestly, the main value that I get from this is for producing a highly optimized crank axis height in my design.
Let’s setup a comparison. Looking at just the front wheel trail and the front wheel flop, what would be different if the system had a slider aligned with the steerer? Otherwise, offset was adjusted so that both were 44.1mm at 30%. That was the only other driving parameter changed. I show that below.
While the flop changes a trivial amount, the front wheel trail change is measurable. The front wheel trail at 100% compression is 68.3mm from 90.8mm at 30% with the angled slider. 65.9mm from 90.8mm at 30% if the slider plane was parallel.
That’s 24.8% reduction in trail for the 1.5 degreed slider and 27.4% reduction if it were straight. A 2.6% difference from 30% sag.
Looking at the difference in trail change alone, one would imagine that this is enough of a marginal gain to be worth the effort. Who wants their bike to become less stable in the most extreme of situations, even by just a little bit? I don’t.
But the bike is a system and changes have knock on effects. If you rob from Peter, your going to have to pay Paul. What costs are you paying for this imagined advantage?
Most obvious is that geometry planning of the bike gets a bit more complex. This is fine for me but most folks have a hard time with basic planning. I discuss this in the post above about gravel forks. Is the geometry confusion really worth the imagined gain if it results in a poorly planned system that negates that gain.
But here’s the real cost, worse suspension performance. Telescoping forks have serious problems dealing with loads that aren’t aligned with the sliders. As things go from bad to worse, we get something called stanchion bind, where the sliders don’t want to slide due to the bending forces going through the fork. For a long time, this wasn’t an issue for mountain bikes. Head angles were sufficiently steep that station bind rarely got discussed. In 2026 and in the last 10 years, it’s become a real problem. Some bikes have head angles as low as 63° or 62°. The only times these forks are going to even work is pointed down a steep chute. Good in a gravity race, bad everywhere else.
With a gravel bike, that 5° reduced stanchion angle may be aligning the slider to the angle of the forces. …but it’s probably not. Again, my mountain bikes are on the low side of what is common for gravel bikes (70°-72°) and I ride some very aggressive and rocky descents. I’m not looking for a lower angle of slide. A bike that is generally dealing with small surface bumps is going to want something far more vertical for best function. We are only left to believe that the 5° is making gravel bikes work worse in favor of appearance, not better.
While a deep dive into whether low head angles are an advantage for our bike or not is the topic of another post, it should be clear that using a fork that reduces the slider angle to earth 1.5° – 5.0° degrees is not wise for at least 98% of a given offroad ride.
My Starfighter MTB uses a 68° head angle. The Warthog should have a 70.5° head angle. I’ve been looking for ways to increase head angles in the last 7 years to reduce flop and advantage suspension over most of the ride. I’ve got the least to loose using this fork. Others will not be as lucky.
Will you be seeing steeper head angles on new model bikes? Definitely not. My prediction is that most 32″ wheeled bikes will have even slacker head angles or very short front centers or both. Why? Simply, handlebars and stems remain the big problem in commodity bike designs.