Suspension: Front fork, springs on the saddle, fat tyres, sprung seatposts
I've been using 50mm wide tyres on my touring bike, and tried 60mm big apples too, running them at from about 3.5 bar to ca. 1.5 bar (because I don't often pump up my tyres) and I found that fat tyres are a pretty poor form of suspension, quite different from what proponents claimed as being a simple and cheap form of suspension. I will detail the problems I encountered below, and give a list of other options with plus points and negative points.
- Suspension fork: Often complex, will need maintenance. These come in 2 variants:
1. Using a spring or air chamber that gives 'spring', along with a dampening system that works with a piece of metal with holes in it, going through an oil chamber, to absorb the movement energy, i.e. dampening of the motion by converting the motion into heat. These can often tuned to your preference with air chamber pressure and the holes or size of them that are open at a time (e.g. on the Cannondale Headshok DLR you can set the reverb). These need maintenance and repair costs when some part wears out can be high.
2. Using elastomer suspension, where the dampening is passive, from the deformation of the material which converts movement energy into heat. Advantage: No maintenance required, other than keeping the legs of the fork clean/rustfree (usually done via a rubber boot which you may need to replace after a few years).
On roads with tiles or bricks or cobblestones a proper fork with oil dampening works very nicely, elastomer suspension is clearly inferior.
A downside to a bike without suspension fork is that with most of them you can feel the weight when turning the handlebar. This is why I like the headshok, the extra mass is in the centre which means it feels easier to steer than a standard suspension fork, this is similar to a light vs. heavy front tyre: The gyroscopic effect will make it harder to turn the wheel when when using a heavier tyre...
- Fat tyres: I used 50 mm Schwalbe Marathon, 50 mm Continental Contact speed for the front, because of its low weight to minimise the gyroscopic effect, and 60mm Schwalbe Big apples, at pressures of ca. 3.5 bar down to about 1.5 bar and that is about the point where you really feel that small bumps are not transferred so much, but at the same time you feel other effects caused by running the tyres at such low pressures:
All in all I don't like running wide tyres at low pressures, it gives too many issues. A proper suspension fork is far better for any situations where you need it even if they do not absorb the really small bumps that a fat tyre at low pressure can absorb. The only reason I like wide tyres is that with them you can run across anything, including open sections of road when there is road construction going on. For an example see my critical youtube channel (critical analysis of events/situations and the people responsible for them), where I show a section of 1 km of road within a village that I often ride through, that was being worked on for 1 year! For this situation I often just rode across the bad sections and sand, without getting off. Though for too loose (dry) sand the Continental Contact speed is not very well suited as it is too round instead of more flat. If it was more flat that would have meant more rubber and thus that would make it heavier so there is a trade off. With this tyre it meant that on loose sand the front wheel would slide left of right and then I needed to walk. Perhaps there are better options than the Contact speed?
- On straight flat smooth roads you will notice it's harder to turn the wheel from the added contact area and from the tyre's deformation when turning.
- On straight roads with some bumps in it you will notice bouncing a few times (I notice 2 or 3) after a bump or lowered section. I don't like this bouncing-around feeling
- On cobble stone roads you may feel as on rails, the deformation of the tyre means the tyre deforms to fit the bumps to the left and right, i.e. as if you run a tyre in between 2 rails if the bumps are located next to each other, and it is then hard to turn the wheel.
- On roads with tiles that have uneven sections you will notice that you feel steered along certain edges where tiles are higher. This is a very disconcerting feel.
- On cattle grids (not just used to keep cattle from crossing certain sections, but also used in NL on bridges to let rain water go through), you feel very strongly as if on rails, it's hard to steer, you will feel guided into one direction, i.e. small adjustments to your direction are difficult.
- Saddle with springs: E.g. Brooks B67, B66, Flyer etc. See my saddle review page for my experiences. Here I will give a brief overview: I think soft springs on a saddle work quite well in absorbing shocks, but not the hard ones on Brooks saddles since about 2000. They don't give the issue with changing saddle height that a sprung seat post gives, they have no stiction so work instantly, that there is no dampening of movement is not an issue, I guess your body does it :) An advantage over most other forms of suspension is that this is maintenance free.
- Suspension seatpost:
There are several types, usually coil or elastomer suspension and no oil-dampening. Then there is a difference in how it works:
1) with the seatpost's saddle clamp moving straight along the line of the seat post (I used 2 of these, a cheap one and a much more expensive airwings seatpost),
2) with a system that makes the seatpost's spring move via a lever to convert the vertical movement into angled movement, such as Suntour's NCX (spring in the seatpost tube) and the Thudbuster G4 ST (elastomer outside the seatpost tube).
The problem with the first simple type is that the force from bumps is up-down, at an angle to the movement in the seatpost, which means more friction, i.e. they don't glide so easily, stiction is high, small bumps don't get absorbed so well. Of the second type I've only tried the Thudbuster which is maintenance free. Downside of the Suntour NCX is more moving parts, and more maintenance. I didn't feel much improvement from the Thudbuster ST despite using a softer elastomer than is recommended for my weight...
Last modified: 2023-1-29