Your video's are just so amazing. Can you do a tuning video on the 2023 ktm 250 xc line in particular the issue with the shock and the faster shaft speeds and if you have any particular mods for the compression side that you like with or without a spring conversion. Great vids!!!!
Thanks mate, another great explanation. I’ve been struggling to understand suspension for years and moving disciplines has actually helped quiet a lot. Really cool seeing what I think is a hydraulic bump stomp (from 4 wheeled offroad racing) incorporated into a shock. Avoids an enormous amount of complexity with extra mounts etc. I think I’ve struggled to understand that all the fancy marketing stuff has convinced me that some random new creation is “alien technology”, when the important order is the geometry is correct, the spring rates are correct, the compression is correct and the rebound is correct. Mtb manufacturers talk about geometry, but almost no-one else. People are selling fancy multistage dampening instead.
In MTB the motor is given the utmost consideration because "You" are the motor..... How power is being generated through the bike is critical to maximising its delivery as well as managing fatigue. The geometry is vital. It's the same for motorcycles but for some reason is largely ignored.
Great info as usual. I was wondering what is the history of the PDS shock system? Was it Husaberg that originally came out with this and then adopted by KTM ? Seems nobody else does this on MX bikes? Odd that after all this time the manufacturers still haven't got it working right yet ?
Great stuff Terry. Do you have anyone in the U.S. you partner with to duplicate the work you're doing? Very interested in it for my '24 after watching this..
No one that we partner with. We are the Race Tech importer for Australia but they have their own agenda which appears to be not very open to outside ideas
Whether you use a bladder or a piston, the gas will be compressed on the compression phase and will expand on the rebound phase. The hydraulic force acting on the reservior is being generated from the shock shaft entering the shock body. Two things are at play here....force and friction. Hydraulic law.... Force = Pressure x Area. Due to the greater surface area of the bladder, more force is generated making it easier to compress. Add to that the fact that there is almost zero friction from the bladder and you eliminate several unwanted issues that are associated with the piston. If you change the bladder for a smaller or larger item, you also alter the surface area which naturally affects force accumulation.
Ha ha.....I don't mind the chains. I love the US and the American people but I just can't handle the mandatory tipping system.... It has gotten out of hand
KTM goes on about all their engineering and suspension development yet keep doing obviously silly stuff ups. It appears it’s on purpose to sell ‘upgrades’
@@Cookie-pct It's a little different but mostly similar. The force required to suspend both bike and rider at sag level will be exactly the same no matter which spring you are using. But it is safe to say that the progressive spring may have already started to escolate in spring rate prior to sag being achieved....but not by much. So if you could achieve desired sag with a 7.6 kg/mm linear spring, you will be very close, although a little lighter in initial rate with the progressive....perhaps a 7.4 etc
It will amazing to listen you about hardenduro and superenduro settings beyond traditional enduro or tracks.
Agree. Hard enduro.
We could certainly look at that
Great stuff as always Terry very interesting and well delivered
Glad you enjoyed it
Love your stuff Terry.
I've used progressive springs and bladders for 18 years.
Bladders are so obviously simpler, supple and highly underrated 👍
Thanks for sharing
Hi, thank you for this great content. Is this rebound issue fixed on 2025 models?
Your video's are just so amazing. Can you do a tuning video on the 2023 ktm 250 xc line in particular the issue with the shock and the faster shaft speeds and if you have any particular mods for the compression side that you like with or without a spring conversion. Great vids!!!!
Cheers. Did you see our clip on the AER fork? You can revalve the comp and change the mid from a clamped shim arrangement to one that has some float.
Thanks mate, another great explanation. I’ve been struggling to understand suspension for years and moving disciplines has actually helped quiet a lot. Really cool seeing what I think is a hydraulic bump stomp (from 4 wheeled offroad racing) incorporated into a shock. Avoids an enormous amount of complexity with extra mounts etc.
I think I’ve struggled to understand that all the fancy marketing stuff has convinced me that some random new creation is “alien technology”, when the important order is the geometry is correct, the spring rates are correct, the compression is correct and the rebound is correct. Mtb manufacturers talk about geometry, but almost no-one else. People are selling fancy multistage dampening instead.
In MTB the motor is given the utmost consideration because "You" are the motor.....
How power is being generated through the bike is critical to maximising its delivery as well as managing fatigue.
The geometry is vital.
It's the same for motorcycles but for some reason is largely ignored.
Great info as usual.
I was wondering what is the history of the PDS shock system? Was it Husaberg that originally came out with this and then adopted by KTM ? Seems nobody else does this on MX bikes? Odd that after all this time the manufacturers still haven't got it working right yet ?
The PDS came out in 98 with KTM. It's not bad but will never beat a linkage
Great stuff Terry. Do you have anyone in the U.S. you partner with to duplicate the work you're doing? Very interested in it for my '24 after watching this..
No one that we partner with. We are the Race Tech importer for Australia but they have their own agenda which appears to be not very open to outside ideas
I have a 2017 PDS with bladder and progressive spring. Is there a rebound separation valve for older Xplor shocks?
No need. They have one in there as standard fitment. You just need to drill a bleed in the centre of it to make it work properly
really good!
Thanks!
Is there any books you would recommend reading to improve knowledge on suspension.
The most comprehensive publication is the Race Tech "Suspension Bible"
How does changing the size of the nitrogen bladder affect performance of the shock? Just curious.
Whether you use a bladder or a piston, the gas will be compressed on the compression phase and will expand on the rebound phase. The hydraulic force acting on the reservior is being generated from the shock shaft entering the shock body. Two things are at play here....force and friction. Hydraulic law.... Force = Pressure x Area.
Due to the greater surface area of the bladder, more force is generated making it easier to compress. Add to that the fact that there is almost zero friction from the bladder and you eliminate several unwanted issues that are associated with the piston.
If you change the bladder for a smaller or larger item, you also alter the surface area which naturally affects force accumulation.
Smartest guy on off-road suspension should be making a mint in the USA but instead he’s locked on a prison colony. Free Terry!
Ha ha.....I don't mind the chains. I love the US and the American people but I just can't handle the mandatory tipping system.... It has gotten out of hand
KTM goes on about all their engineering and suspension development yet keep doing obviously silly stuff ups. It appears it’s on purpose to sell ‘upgrades’
Exactly.
The forks are great....just need some tweeking. But the shock is a little wierd. Its like no one did a simple push test on the seat once it was done
$12,00 for a bike and then you need to spend $5,00 on suspension, yet people keep buying them.
How can we work out which progressive spring rate we need for weight? Presumably it will be different to working out for straight rate ??
@@Cookie-pct It's a little different but mostly similar. The force required to suspend both bike and rider at sag level will be exactly the same no matter which spring you are using. But it is safe to say that the progressive spring may have already started to escolate in spring rate prior to sag being achieved....but not by much. So if you could achieve desired sag with a 7.6 kg/mm linear spring, you will be very close, although a little lighter in initial rate with the progressive....perhaps a 7.4 etc