Suspension Smith

28/08/2026

Heres a really good SRAM/Rockshox article on the development of the latest Boxxer DH forks.
https://www.sram.com/en/rockshox/learn/fork-deep-dives/boxxer-development
It goes into some detail about developing the relative different rigiditys of the forks based on rider feedback and test bench testing to find a great compromise for a much better fork, I agree with all thats said.
It goes into some detail on how the riders disliked the overly structuraly rigid forks as they are generally harsh and uncompliant, lacking traction and feel then goes into how they fine tuned the rigidity balance to find a setup the riders were happy with.
But note its generally about compliance feel and reducing vibration coming through to the riders hands/arms etc, DH is a very physically and mentally demanding sport so this is very important.
What its essentially doing is introducing a level of structural compliance in a certain direction because the Teleforks linear single directional travel is simply unable to provide enough compliance.

Now my goal is to take this a step further, develop a system that gives a better overall suspension compliance.......suspension compliance in terms of multiple suspension travel vectors with springs and dampers, not using structural flex/rigidity balance to acheive compliance.
My system is introducing a second in series link suspension system which gives to the front wheel a second wheelpath, a wheelpath which is more rearwards and so sensitive to a much wider set of bump force vectors, small / medium / large bumps etc, its also completely tunable via a second air shock so tunable spring rate,progression and a state of the art tunable/adjustable damper.
And it doesnt end there, I have built in a link geometry adjustment where I can quickly and easily change the direction/angle of this second wheelpath, so it can be optimised for a given set of trail conditions/type and circumstances and rider preferences.
If you took note of my so far measurements of fork flex you can see that structural flex is measured in terms of single figure millimeters, and that gives noticeable effects in feel and vibration compliance.
My second in series suspension gives/adds 55mm of travel, massively increasing the levels of "controlled" compliance that can be acheived.

BoXXer Development

26/08/2026

One aspect of the dual suspension I spent a lot of time refining was the one piece fork crown.
A regular double crown fork crown is made up of 3 pieces clamped together and precise alignment is crucial to get the two fork stanchions aligned absolutely parallel to each other for lowest stiction and friction for suspension sensitivity.
But the rigidity of this 3 piece fork crown is ok but not great, under high loads, cornering/bumps and hard braking the fork stanchions can twist in the crown and misalign and fork causing binding and high stiction/friction is the result.
There is talk of designers building in some degree of flex into the crowns and also the lowers to aid compliance in certain situations, some degree of lateral flex is useful, any degree of torsional flex is not.
Problem is that designed in flex is going to cause binding and stiction etc in the forks, maybe the hope is the flex helps offset the negatives of binding.
I think in something as sensitive to binding flex as a telescopic fork its best to avoid it entirely.
I have been following a train of thought to design a system that maximises the alignment rigidity of the telescopic fork structure, yet can include a tunable degree of lateral flex that is seperately independant to the Teleforks structure so doesnt effect the action of the telefork....when the tunable flex occurs the telefork continues to work at its best and indeed better because under high loadings the stiffer fork structure doesnt bind at all.
This one piece fork crown is a deceptivly complex bit of kit, keeping it light and easyish to make was a challenge.
Bolting the fork stanchions in is straight forward, rigidly bolting the upper and lower links in was much more complex, the idea was that the upper and lower cross bolting of the links into the Crown would further stiffen the crown, the problem to be avoided is when simply cross bolting in the links it can distort the crown enough to misalign the fork stanchions, which defeated the whole purpose.
The fix was a similar arrangment to the way the fork lowers bolt onto the wheel axle, pinch bolts both sides, but when the axle nut side only is tightened up and piched the other side is left free to float on the axle to self align, no side forces are imposed on the structure, then the pinch bolts on that side or tightened up and your away. Job done.

23/08/2026

Heres a look at the new versus old upper link arrangement I am looking to try.
There is a bit of Lateral movement/flex in the front suspension and whilst it so far to me it doesnt appear as a problem, I think a more agressive rider may find issue.
So I have designed a new Laterally stiffer upper link and it will be interesting to see what this does.
Now I dont mind Lateral flex, if its controlled and of a useful amount it can improve compliance etc....by the way,in my opinion Torsional flex is bad in any extent.
Previous studies I have done has proven Lateral flex in front suspension is a useful thing, it just needs to be controlled and if possible have some degree of damping or Hysterisis.
Rear link suspensions use Lateral swingarm flex and some have replaceable bits to fine tune it to circumstances.
Interesting to think that I could easily have a range of upper links with different Lateral characteristics to fine tune with, maybe even design in a small two way adjustable damper.

21/08/2026

Here is the Lateral flex test, again each suspension is rigidly mounted in the Dyno with the difference here is that the fork axle is free to move, being not fixed I am also applying a 150N force to the left end of the axle and pushing left to right on the axle and I have the digital indicator gauge mounted to the other end of the axle to measure deflection.
Here the Dual suspension gives a deflection averge of 5.262mm when a 150N force is applied.
The stock Fox40 fork gives a deflection average of 3.942mm with a 150N force.
This shows the dual suspension is more laterally flexable than the stock Fox40, something like 33% more.
Is this good or bad?
Mmmmm I have not noticed anything negative, the bike steers really well, at least in the way I have been riding it.
This suspension has amazing compiance when hitting big stuff hard and doesnt deflect off stuff, it always retains good directional control for the rider.
I suspect that a more aggressive rider riding in say a bike park setting with a smoother grippier trail maybe where much more aggressive steering inputs may see this being a issue.......
What I am going to do is have some new parts made,I have spent some time taking a close look at where this Lateral flex is taking place and it appears to be at the upper link, which in hindsight is a bit anemic looking, I plan to have a laterally stiffer upper link made and a corresponding stiffer handlebar stem to which it pivots off, then do some more testing and see what results.

21/08/2026

So getting a bit more in depth onto the structural characteristics of my Dual suspension system.
When I first built it I did the usual basic test of putting the front wheel between my knees and twisting the handlebars to get a feel for the torsional stiffness of the front suspension, comparing this with the stock Fox40 forks as found on the Zerode G3 downhill bike.
I found the dual suspension to be noticeably stiffer in that torsion test compared to the stock Fox40, in fact any dual crown fork I tested, now that test isnt real accurate but the difference was there.
Anyways I decided to test this properly, one of the things I have noticed about the in series dual suspension when riding it through rock gardens etc is how directionaly stable and predictable it is to steer through the rocks etc..... a torsionaly stiffer front suspension would explain this.
So I have used the recently made fork fixture for the Laba7 spring dyno to rigidly mount both the dual suspension fork and Stock Fox40 fork into the dyno so I can accurately test both their Torsional and Lateral rigidity and quantify and compare it.
I have just completed a bunch of testing to that end and tried a few different methods to test this, now settling on this set of methods as a accurate and repeatable way of getting this data.
The following pics show each suspension mounted in the Dyno fpr the method of testing torsional stiffness, this is fixing the fork axle rigidly whilst applying a 150N force to the end of a dummy handlebar and measuring the flex at the other end of the bar, this measures the Torsional flex from the fork axle right through to the handlebar stem mount.
With a 150N force applied would see an average flex of 4.63mm for the dual suspension and 8.81mm for the stock Fox40 dual crown fork.
Hence the dual suspension is 90% Torsionaly stiffer than the stock Fox40 dual crown fork, as I suspected.

28/07/2026

Been doing a bit of tinkering with the MTB Dual suspension mounted in the Laba7 spring tester.
I have been getting a feel for how the in series Telefork and Link suspension interact with each other in the MTB Dual suspension and how they build spring force through the travel with various different settings.
Found some very interesting characteristics.
I have two basic setups I have been developing, the A setup which I have been running on the Kenevo ebike is a very plush,high sensitivity setup that maximises compliance above all else,small/medium and big bump compliance is exceptional.
The other B setup, is a more stiffer Down Hill orientated setup giving more holdup in the front with quite excellent bottoming control and feel but still with very good overall compliance and sensitivity etc.
The following graphs show where I have experimented with each setup by only changing the air pressure in the Ohlins Link shock and testing the resulting spring force curves.
Each A and B setup has slightly different settings in the Fox40 fork, the A setup uses a 60lb/inch main spring at 180mm of fork travel.
The stiffer B setup Fox40 fork uses a 65lb/inch main spring at 180mm of travel.
Both setups use the 55mm travel link suspension giving 235mm total travel with the Ohlins air shock.
As a comparison in each test I have included 2 tests of the original Fox40 air spring at 200mm travel with 3 volume spacers at 90psi and 100psi.
Each of the following graphs will be anotated with a relevant description of the test.

07/07/2026

One of the features I have developed on the Kenevo dual suspension is to utilize the lockout on the ohlins TXC2 air shock, being a XC based rear shock originaly, it has a cable operated total lockout feature on the shock ment to lockout the rear suspension for better pedal efficiency on hills etc.
I am using this lockout feature to firm up the front suspension in situations where you dont need so much suspension travel and plushness, say on a faster smoother hardpack trail section where you need more support and holdup in the front suspension for aggresive steering braking and cornering.
The following graph shows how the spring force curve is changed by the lockout and how much it firms up the front suspension just with the flick of a lever on the left bar, it also shows how the full suspension travel is still preserved tho, the lockout gives a very firm damping resistance but it has a threshhold built in where once the total spring force gets beyond a certain point this force forces open the lockout and allows the full suspension travel of the Ohlins shock but still with quite high damping resistance, think of it as a very long travel hydraulic bottom out.
When riding this on smoother gripy hardpack trails it makes a huge difference in feel in the front suspension and steering.

07/07/2026

Heres a comparison of the stock fox40 air fork at 90psi and 3 volume tokens and 200mm travel, against the Kenevo dual suspension as tested previously.

07/07/2026

Well I have completed some initial tests on the LABA7 dyno with both a set of stock Fox40 air forks at 90 psi and 3 Volume tokens as a comparison with the dual suspension tested as taken straight off the Kenevo E bike.
The dual suspension on the kenevo I have been riding with a smashpot spring conversion in the Fox40 with a 60lb ( 1.07kg/mm ) main spring and a 275lb ( 4.9kg/mm ) secondary spring.
The ohlins TXC2 link shock was run at 85psi with additional chamber volume for a less progresive air spring.
The following Vid shows the Kenevo dual suspension being pushed through its 235mm of travel.
In the below vid notice that at first only the fork is moving through its travel,its only once the fork is at around 60mm into its travel that the top link suspension starts moving and as the fork further compresses and its spring force further builds then the Link suspension starts moving faster into its travel...here the Link suspension bottoms first, with around 20mm of the forks travel left to go.
In the attached Pic is the dyno graph of the spring force curve of this test and the resulting spring rate graph in the second Pic.
https://youtu.be/Gs-o1MlGiso?si=xJALwCpQPcg0AUhV

02/07/2026

Anyone following this page will be aware I have lately been developing a new type of front suspension for mountain bikes.
Still moving forward with it and making pretty good progress,I think this is definately a great thing.
For the past 6 months I have been doing my own riding and lots of testing and the only problem has been my age,I recently turned 60 and I am finding the limits of what my body can now do, the mind is fine, its like riding a bike, you never forget how.
Still I have great overall health and no real physical health issues limiting me, its just the challenge of getting fit and staying fit enough to ride a mountain bike hard enough and staying injury free.
The ebike I am riding is a godsend,its the only reason I can still ride and enjoy it.
Anyways so yes for the last 9 months really, I have been riding almost daily the specialized Kenevo comp with the dual front suspension fitted and been loving it.
I have played with so many different configurations of the dual suspension along with 27.5 and 29 front wheel sizes and steering geometry that comes with that size,the front suspension has a load of adjustment built into it and having a BYB telemetry system fitted during a lot of that testing has showed some very interesting data.
What the addition of a second in series suspension system can give to front suspension capability is phenomenal, I am completely convinced that this is the way forward in say more gravity based MTB riding over very difficult/challenging terrain.
So my latest effort which I will write about is about doing more in depth analysis of whats going on, I have developed the front suspension on the Kenevo to what I think is an extremely capable setup for very rocky, rooty,rutty trails, its steering geometry is a bit of a compromise as in my persuit of suspension perfection it has 235mm of front travel in a frame originally built around 180mm of front travel, so the front is very high and raked out, really it needs a frame specifically designed for this front suspension.
Having said that once you adjust and ride accordingly, it steers pretty good, especially when the going gets very gnarly and fast, stability capability and hence predictability are great.
This bike is a sledge hammer for smashing through terrain, not a knife for carving through it like a typical Enduro or XC bike.
So one area that has been missing in my knowledge has been how the two interacting suspensions, one a telefork and the other a linkage suspension, working in series, effect the overall spring forces at the axle.
This has been something which I have not been able to simulate in any meaningful detail and have had to rely on learned intuition to work out what should work in designing it and then testing to find out what does work in practice.
So now having a very capable front suspension setup which seems to tick all the boxs I have come up with a way to accurately test and quantify what I have.
I have had a Laba7 spring rate dyno for about 3 years now and its a very high end bit of kit for testing spring forces in forks and shocks etc, I have been meaning to do this for a couple of years now but only recently have I had the opportunity to do this, this being to build a fixture into the Laba7 which would allow me to fit and test my in series dual suspension system right through its total travel to find out exactly what its spring forces are at the axle.