Mountain Bike Suspension Tuning At Mojo Rising


– Mountain bikers are a varied breed. There are some of us that
have no interest whatsoever in opening up our suspension units. Some of us, might be quite
comfortable doing a lower leg or an air can service, but not much else. The next layer is people that are comfortable rebuilding dampers. But the top slice, are
the suspension experts that tune the suspension to the rigors of the rider, and the bike. We’re here at Mojo Rising
for a real interesting look at what it takes, and what goes on inside a suspension tuning workshop. (upbeat music) Mountain bike suspension
has come a long way, and it’s pretty incredible. Now if you don’t believe
me, I suggest just googling mountain bike slow-mo and
see how hard the units work as they suspend us to give
us both grip and drive. It’s pretty incredible. But what if you want
to maximize that grip? Obviously, you can tinker
round with your spring rate, or air pressure, as well as
the external adjustments, such as rebound and compression. But what about the next step
to achieve the optimum set up? Well, you’re going to have
to start thinking about changing the internals of the shock. This is a bit of a dark art, and takes experience and expertise. For instance, you could be
a truly excellent mechanic. But, until you’ve worked on
a particular model of bike, you’re never really going to
know the true nuances of it until it’s in front of your very eyes. It’s that level of experience
that comes into play when you’re doing the fine tuning. We sat down with Chris
Porter, the head honcho of Mojo Rising, to discuss the basic needs and available refinements
of mountain bike suspension. As somebody that runs
a suspension workshop, amongst other things,
what would your advice to a consumer, to an owner
of a high end mountain bike, on maintaining their shocks? – Yeah. My advice would be don’t do
more than you need to do. You know, if everything’s working well. And you’re happy with the
bike, and how it’s handling, leave it at that. If you think you need more, and
not happy with the handling, then think about either doing
something about it yourself, which is much easier at
the front end of the bike, and to a certain extent,
I’d encourage all customers to learn how to do a lower
service at the very least. And then the next level above
that would be the shocks. So I’d say, learn how to
do the lower servicing to keep everything
friction free and smooth. Do that maybe two or three
times over the course of a year. And maybe when you’re
sending the rear shock off for a service or a tune, send
the forks at the same time. You know, don’t overdo it. – I think when you get into
servicing your lower legs, it actually becomes a lot smaller of a job than a lot of people think. – Oh.
– It takes, you know. – Oh yeah for sure. You know, when you first
do it, as a beginner, and you first drop the lowers off, you are going to be terrified, every tool that touches the fork, ah, this thing cost so much, it’s going to cost me
fortunes when I ruin it. And the truth is, it’s
just nuts and bolts. – But what I, I completely agree. I think, you know, lower
legs should be available at most bike shops.
– Oh yeah, easy. – I think it’s the difference
between washing your hair, and cutting your hair,
do you know what I mean? – Yeah, yeah. I wouldn’t know, either.
(both laughing) – I don’t want to get into my hair cuts, because they seem to be
just a comedy of errors. But, in terms of going into
the more complex dampers. Is there any pitfalls of
that for the home mechanic? – Of course there are. Just know your limits. When you reach the limit
of your understanding, you know you’ve reached the
limit of your understanding. Stop.
– Yeah. – You don’t guess, don’t guess. If you don’t know what
you’re doing, stop there. If you’re confident to have a go read a YouTube video, they’re very useful, YouTube channels, others
are available I hear. – Oh stop
(laughing) – But if you’re confident to have a go, have the tools, are good with tools. Then, you know, it’s not that difficult. But know it. Know you’ve reached it,
and don’t have a go. Don’t be a have a go hero, kids. (both laughing) – Now, we have your bike just behind us, so I think we should go
over some of the parts, and just talk about sort
of, service intervals, and the different things that might wear, or kind of, be prone to needing a service. – Yeah. That’ll be quite useful
for people I think. – So if we actually look at, this is your bike in particular, let’s look at the problem
areas and the issues that might inhibit
performance, and what would be suitable to do at home, and
what might be a bigger job. – That’s a good idea. So if we start with what
the suspension does, what the parts do and don’t
do, then you kind of understand what’s going to inhibit the
performance and what’s not. So. The job of the suspension
is to suspend the rider. There’s a spring medium,
we’ve got a spring, we’ve got an air spring at the front, a coil spring at rear. All different types of
springs are available. But, the job of that spring is literally to support the weight of the rider, and the sprung portion of the bike. So, it just sags into its travel. That’s an undamped motion,
that supports the weight. The damper has a different job. There’s a damper in the fork, there’s a damper in the rear shock. That does the job of slowing
down the amount of movement that the suspension is doing. With a coil spring, it’s
difficult to think of a way that that’s going to get damaged so we lose performance in a coil spring. In an air shock, or an air fork, it’s really easy to understand how, if we do a quick service
and scratch a sealing out, or if it’s accidentally, or twist a seal– – Or even a seal
– As it goes in– not going in straight.
– Yeah, yeah. – You see that sometimes.
– Twist a seal as it goes in. Then we won’t have a
proper sealing system. We won’t have an air tight air spring that will resist and support our weight, we’ll just have something that won’t work. So, at the very basic
level, the sliding surfaces and the singling surfaces
for an air spring are really important. Do not go at those– – Not with a file.
– With a hammer, hammer and chisel, or don’t hold them with any tools. These things, those are really important. One of the other things I
try and encourage customers and anyone to do, is not to
think of suspension tuning, as in twiddling these things, as complex. Don’t overthink it. If you’re going to go out and
test another couple of clicks on that, don’t think, right
how did that affect it? was I getting better grip on
the off camber, or you know, don’t overthink it. Just say, right, was it
better, or was it worse? – And also, try it. – Definitely. Definitely try it. Because that is so easy to undo. If that was the magic position, there is no magic. This is not the magic
position, but it’s okay. Because I can go back like that. It’s really simple. So, try it. I’d encourage everyone just
to try more compression, less compression, was
it better, was it worse. If it gets better and better and better with more and more compression
on the rear damper, let’s just suggest… You run out of compression
damping adjustments, but you’re still wanting to try more. Then this is where you think
about going to a tuner, to say, “Can you get more
physical compression damping into the actual damper before
I start using the adjusters?” – [Presenter] So what kind
of jobs could, you know, any number of suspension centers do, you know, I’m thinking of,
people sometimes might have play in their forks and never be able to work out where it’s come from. But I suppose bushings
and things like that is something that you can do here? – Most decent mountain bike
shops will do a fork service, but you’ll need to do a level
up to a suspension center to get your fork bushings
replaced, usually. It just requires more tooling,
and more knowledge is all. Which is something that you
take to a suspension company. – So I imagine, when
you have customers that have quite a kind of
hard problem to solve, or something they’ve at
a bit of a dead end with. – Yeah.
– You know, having that dialogue with them must
be invaluable for that. – Yeah, obviously the kind
of questions you get asked, a huge range, you know. From little ticking noises, to you know, really intricate damping questions. But, again, you know,
if you are speaking to a suspension company with
a few years under the belt, then there’ll be normally
something in the history of mountain biking that you can remember, and go, ah, you’ve got that. – Yeah.
– Kind of– Yep, that kind of–
– Yeah, or that model. – Yeah, ah, right, okay. So, the fix can come from
any number of places, so for a customer to be saying to me, “Shock’s making a little noise.” Really, you need to take that to someone to find–
– Yes, completely. Yeah, yeah, completely. – I can’t see it, so. – After talking to Chris
about, not only the option of external adjustment,
but also the necessity of experimentation as
we try and understand and optimize our bikes,
we stepped into a service with Jack to look at
the internal adjustments and tuning options. – So as you can see
now, we start with some 15 mil shims, effectively,
just for spacers to make up the distance
we’ve got on the piston bolt. And then we sort of get into a compression and rebound stack. So that there’s, is our rebound. – [Presenter] So once, now we’ve
taken apart the shim stacks there, what would be next, what
part would you go into next? – So we’re just going to
continue with the bottom half of the shock, so this
is your main seal block. As you can see in there,
there’s the main seal there so we can replace, replace that one there. And there’s an outside
seal, which is just a seal between the seal block and
the body, stop any leaks. So we can do that. And we can go further again. (machinery drowns out speech) – And there it goes. I suppose this is where
having good quality tools like you would get in a
suspension tuning workshop, comes in handy. A solid vice, all at hand, you know, you’re not rounding anything out, you haven’t got it in… You know, you’ve got some nice,
kind of soft jaws on there. – So this is just, derailleur and shaft, there’s no seals in this
part of the shock now. So that’s locked tight in,
hasn’t made it’s way lose, it’s not going to make its way lose, so we’re happy to leave that. We can clean out all the lock
tight at the top of the shaft, just so when we’re
re-applying the piston bolt, it’s going in flush. Not cross threading
anything on the way in. The shafts are specific to the clamps. So they’re correct diameter
so we know that when we tighten up any part of the shock we’re using the correct equipment. Not recommended to be bodging your. – [Presenter] So when you’re
doing a service like this, do you inspect seals, do you
replace them irrespective, or? – So, with our top tier service,
we change all the seals, static and sliding. With a medium tier service, we do sort of sliding
seals, and inspect the rest. With a sort of lower tier
service, sort of re-valve, we just do the work, the labor, and inspect the seals as we go along. – Yeah, I think that’s really important. Cause sometimes when people look up their local suspension
company to send it away to, sometimes they don’t realize
the cost includes the seals. – Yeah.
– And so they think, oh my god, that’s really expensive. But actually, just one set price, and you know everything’s
going to be done. It’s not so bad. – Revan rod seal changed,
piston bolt seal changed, and we’re just going to reapply it. So we want the revan sort
mid-way in it’s range, just so that the needle drops in. And it’s not pushed to either
side when we’re installing it. We’re going to be
adjusting the compression, on this customers shock. So at this point, you
know, this is where I would look into that, get what shims I need… Ready to go, and then look at what point I’m going to be adjusting the compression. So, for example, this
customer’s looking for more mid to initial stroke support. So I can look at the shims, and
concentrate on that one area of the shim stack. I clean all the shims up, measure them. Make sure that all these shims are good before we start. To make sure the rider
wasn’t having any problems with damaged shims, before we start. And then I would liaise
with Chris for example, or get a drawing, and
work out where I go next. And then start adding my compression shims in the right area. – You know, you get somebody
that’s a good rider, out every weekend. Do you think that they would
be able to really notice, and benefit from a more
tailored shim stack? – Yeah, yeah, definitely. I’d say, if you want to
step outside of tunes, which are bike specific, and
get a tune which is better for you as a rider, and your riding style, I think someone would definitely… Or anyone, any capability
of riding, would benefit from having their shock or fork set up more specifically to them. (spanner whirring) So at this point, you’re just sort of, pitting your way through
the shock, replacing seals, and then inspecting parts
for damage, as well. Next step is going to be to bleed. So you want all the
adjusters open to start. And we’re going to go
for the hand bleed today. We have got a vacuum
machine, which is just there, but a hand bleed you can
physically see the bubbles coming out of the shock, and
that’s going to be better, better for this So now we’ve got oil in both sides, and what you’ll see
now is when we push the IFP into the reservoir, that
oil is then going to be pushed down through the shock,
through the high speeds, through the lock out, and then
back out into the main tube, and you’ll see this oil level rise. So, the IFP is as far in as it can go. And we’re just going
to measure from the top of the reservoir, to the
underside of the head on the bolt. And that’s giving us, seven mil. – So then you can–
– We can go to 12 mil, that’s our IFP depth. Drop the shim stack in oil, and we adjust the rebound as well, so what you’re doing is
moving that rebound rod up and down the shock, pushing any air out through the shim stack. – [Presenter] That’s a nice trick. I’ve never, never done that before. That’s pretty nice. – So we’re just working in
the opposite direction now, we’re pushing the oil back through. So you’ll see the bolt rising, which means the IFP is rising. So that’s hand tight,
and again, specific tool to be able to torque this up. So we’ve added compression
to the shim stack, more compression, so we’re going to go up with the reservoir pressure,
only sort of 10 psi. To sort of counteract what
we’ve done to the main piston. – And it comes back to that,
yeah, displacement again. – [Jack] Yeah, yeah. – [Presenter] And there
we have it, that’s how to, I suppose, do a custom tune on a shock, you know, with a customer in mind. – Yep.
– And make it for somebody, not for everyone, which I
think’s actually pretty cool. – Yeah. – Awesome, well thank you
very much for your time. Thank you for showing–
– Not a problem at all. – All the nitty gritty, it’s
been really, really cool. So there we have it. That was a day inside a
suspension tuning workshop. It was pretty cool. I think there are a couple of take aways. I think, one, is definitely
there’s a huge amount of knowledge and maintenance
that you can do at home. As Chris was saying earlier on, you know, friction is kind
of the number one enemy. So things like lower leg
service, and air can services, are absolutely vital. The second big takeaway, is that, there definitely isn’t
a one size fits all. Bike designers must have a really hard job specing certain shop tunes,
when they know that any range of weight of people
could be riding it. And, if you think that
something isn’t quite right, then it’s probably worth
thinking about sending it to a suspension center. Something we’re very
commonly asked is that, I might be a heavy rider,
should I ride a coil shock? Well, not necessarily. The coil is just the
mechanism that you would use to suspend the rider,
but it’s not the damping. Something like a firmer compression tune might actually be more beneficial. And that’s when you need
to send it to the experts. It’s been really cool,
super interesting to see all the inner workings
of that shock earlier on. And I really hope you enjoyed it. Now, I want you to have a think and get in the comments below. What would you change about your shock? What maintenance do you do? And what would be your advice to yourself if you’d just started
riding mountain bikes. Don’t forget to like and subscribe, and we’ll see ya next time. Cheers guys.




Comments
  1. This video felt like a waste of time while I was watching it…. but I still couldn’t stop. So it must have been good! I think.

  2. I couldn't find a bike shop in my country that would do a lower leg service on SR Suntours more premium forks, the list of bike shops on their website was a total grave yard. The first 10 on the list had gone out of business at which point I stopped bothering. None of my local bike shops would touch them either because they only did Fox or Rockshox forks (including the shop that sold me the bike), and they didn't know anyone that would work on them. So I didn't really have much choice other than to do it myself or buy new forks.
    It took me a few goes to get it right the first time, but no damage done. There was large quantities of oil in the lower legs, which came as a big surprise considering that SR Suntour forks don't use oil baths and the forks had never been serviced since new. So I didn't know whether to put oil or grease back in to them. SR Suntour customer support helped me out though, they think that the grease must have separated, and told me to fully disassemble the forks and put new grease in. The forks have been fine ever since.

  3. Would have been nice to see a conversation about what changes were made to the shim stack and how much, of what affect it might have.

  4. Wooow this is so interesting loving this type of videos the lads it mojo are some sort of geniuses where do they learn it all 😂👍

  5. Alright this is great content I love this stuff. My dream is to have a setup in my workshop that is equipped to rebuild dampers and eventually get into revalving like this. For the time being I'm going to get some training from the suspension centre.

  6. EXT…very impressive heritage. F1, with Lotus. Invented High/Low speed circuits… #wow #extshox 👍👍👍

  7. #askgmbntech Hello guys, I know that if you lock your front suspension and you hit a bump, you risk damaging it. Does it also apply for the rear shock? Does it matter if its coil or air ? Love the show, keep it up.

  8. You guys forgot to mention trying different weight oils. Definately a step to try before stuffing around with shim stacks.

  9. #askGMBNTech. Hi guys. Great vid, I’m having a problem with my full sus set up and could use some help. I’ve got a specialised Pitch with adjustable front fork and a Fox Float air shock on the rear. I cannot for the life of me get the rebound to slow down on the rear shock. Any advice would be a massive help. Thanks guys love the channel

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