Gravel Suspension: What, Why, Testing and When
In this article, South Africa’s foremost frother of all things Gravel, Kevin Benkenstein, goes deep on the subject of suspension, and what riders can expect from it.
‘Gravel’ means different things to different riders and as that base of riders expands, so do the options for bikes and components.
As the whole Gravel scene is developing, suspension is one of the more polarizing aspects of the genre. “Just get a hardtail” is a common comment, but it’s not quite what a gravel suspension fork is creating, and it takes some time to understand where the benefits lie.
For a year now, I’ve ridden with and without a gravel suspension fork, to try and get to grips with when and why it makes sense and, more importantly, what type of riders would benefit the most from buying one. In a nutshell, here’s the good and the bad of it. The good: There’s more comfort, the bike is more capable and it expands riding possibilities – in some ways. The bad: It adds weight, can change rider position and bike geometry, there will be more service expenses and it limits some possibilities too.
What I rode
Gravel suspension forks started as shortened XC forks, and as such were a bit bulkier and unrefined. The second generation however is more fit for purpose: lighter and better tuned for its use. There are 30-50mm options but I have sat in the middle and tested 40mm forks, with a 430mm Axle to Crown.
The bikes I have tested them on are a Curve GXR Titanium, Curve Kevin of Steel and Factor OSTRO Gravel. These bikes are not designed for this axle to crown and so some geometry changes occurred, which I have had to navigate.
Why I tested them
The majority of my riding is in the hilly terrain of the KZN Midlands where I live. It is either up or down here, and not gently so. In the dry of winter it is always dusty and corrugated while summer alternates between moist and muddy. I want to make my bike more capable, reduce the daily stress on my body so that riding more/longer/harder took less toll and I wanted to have more fun.
I also don’t have a mountain bike, I prefer drop bars to flat bars, am not looking to ride hours of single track and want a bike to still feel like a fast bike when it’s straight and smooth. Outside of racing, I ride gravel bikes exclusively, generally with 45-50mm tyres, and have a bad habit of not following set routes well. Sneaks for life and all that — and I also wanted to allow myself the freedom to do that even more.
My testing process
Over the past year I have ridden both the RockShox Rudy Ultimate and the FOX 32 Taper-Cast forks. I have swapped between them and my normal rigid forks intermittently both in training, riding and racing. We ride mostly open gravel roads, tar and jeep track as daily conditions, with a bit of single track thrown in here and there. Many rides start in the dark, sketchier descents follow with limited light and high speeds, and that, I thought, would be a little nicer to do with some safety net built in. Sneaks, as I said, occur regularly and as forestry creates and closes some forest roads. These vary in quality — as does my decision making — and again the extra comfort helps. If my mates are on a mountain bike ride, and some trail is involved, I wanted to join more comfortably, and maybe show off very occasionally too. I also do longer — like 500km gravel races from time to time and have seen that fatigue reduction matters in those scenarios, so wanted to see if the bit of give would help.
The effect on my bike setup was meaningful. On the Factor, I went from 3cm of spacers under the stem to a tiny 5mm one. On my Curve GXR Titanium I had been running a 5mm spacer so had to change to a negative stem which I did not enjo. On the Curve Kevin of Steel, an XL, I could just use a 5mm spacer and long stem which felt fine. Geometry changes to seat angle and head angle are important to consider and, while they were manageable changes for me, they go against what the bike designer has intended for the bike and so the nature of your bike, and how you enjoy it, might change. Put simply I can envision a situation wherein the benefits of a gravel fork are nullified by the changes to bike geometry and you end up worse off. In future, this will and already has been a major consideration for me when purchasing a bike, and I would hope that brands account for the potential of riders wanting to use a gravel suspension fork, as some already have.
Fork Setup (ie air pressure) matters a lot, as anyone who has ridden suspension will know. I won’t bore you with too many details but I have settled on a softer pressure than recommended by either manufacturer for my weight and chose a faster rebound to account for the higher speed of the vibrations you experience on gravel. In practice, most of the hits I have experienced with a gravel fork on, have been smaller and only once did I bottom out either fork, which was at Unbound XL in a race scenario on an extremely sketchy jeep track. I’m very comfortable that, for the riding I do at least, this is the setup that will work for me going forward.
Tyres matter as much, and it was a bit silly when I tested with 40mm tyres as the tyres were not capable enough for what the fork allowed you to do, but with 45-48mm tyres (I tested up to 2.1) it is a great, versatile and fun setup. I run 45mm tyres with inserts and 25/23 psi for the most part now (I am 80-82kg).
I can safely say I have not settled on a perfect solution, but I have gone from ‘Suspension forks are stupid’ to ‘I always want a suspension fork available’. In fact, in an ideal world, I don’t really see why, money allowing, one wouldn’t have a suspension fork on your gravel bike if you actually ride gravel daily. On road and smooth gravel, even mid-range gravel, there really isn’t much change and certainly nothing that correct tyre pressure can’t fix, but on fast descents I feel faster and safer, when things do get rough you don’t think twice about it. With a suspension fork on, the ‘short lefts’ have been worry free: Who cares how rough it gets when you have 30-40mm of plushness underneath you? Get back on sealed roads or smooth gravel, a quick turn of the lockout and you have a rigid fork again, albeit a heavier one. However I barely fully lock the fork, if ever. As an extra bonus, I find my body less sore at the end of a six hour ride; there really is almost no upper body fatigue.
With the effort put in to ensure bike setup/fit is right I have only seen bike handling improve even if I have had to put a lot of fit into the fit side to keep it correct…I would definitely prefer a bike that comes with a fork that replicates the axle to crown of a suspension fork so that swapping forks becomes easier.
When are they better?
Well, that is the main question I think, especially if you race. If you are a rider who has no interest in racing, even if events are done for fun but with no time-focus, I can high recommend these forks at all times. There are very few routes in South Africa that are perfectly smooth, and the only gravel race I can think of that doesn’t suit one for any rider is Swartberg100, with its high tar percentage. As I have said there are benefits for comfort, handling and a new variety of terrain opens up, and for enthusiast riders, those far outweigh the negatives of increased weight, which is about 700g. Of course there are purchase and service costs related to these forks, but they are worthwhile if affordable for the rider, and they are not exorbitant in the long run.
For an all-out racer, the lines are more blurry as to when to use one. In most cases the weight and less-aero is not ideal but for some events that are rougher and/or longer there is benefit. I rode the Fox 32 Taper-Cast for Unbound XL in the USA for example, and can safely say it made me faster. In South Africa, there are maybe less races where it’ll be suitable though, so I think having it as an extra option, and not the only option, for your bike is important.
For myself, a bike with a suspension gravel fork is now a must-have in my garage. The fun, comfort and variety it adds to my riding life is worth every cent of the purchase and servicing cost. I am confident that the fork will last me years, and so that cost over time is worthwhile. Servicing is quick and easy with normal 50/150 hour intervals and the ‘damage’ done riding does seem to be less than a mountain bike fork would experience. The forks I tested both have their positives and negatives compared to each other, as will the Cane Creek option when it becomes available. Which one you choose will depend on your needs, but my recommendation will need to be via a longer dive into each. //
| WORDS: Kevin Benkenstein for Bike Network |