Does A Chain Affect Mountain Bike Suspension Performance?

Does A Chain Affect Mountain Bike Suspension Performance?


– Chains, we need them, right? But how much do we need a chain? So Aaron Gwin and Rachel Atherton
more recently have proved that you can go super
fast without a chain. Rachel Atherton actually made time on the most pedally section of
Fort William without a chain. But how does that chain
affect the suspension, why does it affect
suspension and can we design a solution to this problem? (upbeat hip hop music) Have you heard of pedal kickback? Well, when your rear
suspension moves, of course, your rear axle moves up and down. But all that does, it puts
tension onto your chain and that restricts your
suspension movement. How do you lose that tension? Well, sometimes your
cassette can roll forward, but it mightn’t always do
that, so it might be breaking. Or your chain-ring can roll backwards, but if you’ve got all
your weight on the pedals that isn’t going to happen either. Therefore your suspension is restricted. How do we get rid of that chain tension? Well, first thing you could do is you could get rid of the chain. We have done that in the past. We’ve done videos where
we’ve just taken it off and suspension works really well. Of course that’s what happened to Aaron Gwin and Rachel
Atherton, but it’s not ideal, obviously you can’t paddle anywhere. The second option is to
invent a neutral gear. (suspense music) This isn’t an original idea. I’ve actually stolen this idea from the UK suspension
wizard, Chris Porter who is known for his innovation of bike design and basically
experimenting with things. All you do is replace bottom sprockets of your cassette with the spacers. Basically I’m going to change down to here and my chain could sit on that, would freely rotate forwards or backwards and completely freeing up my suspension. Is it going to work, is it
practical, am I going to smash my knee into my stem when I try and pedal and I forget that I’m in my neutral gear? Let’s find out. (upbeat dance music) I’m running a Shimano XT, 11
speed cassette, it’s an 11-42. I’ve got rid of those
two smallest sprockets, so it’s nine-speed, I’m sure
you worked that one yourselves. I’ve got rid of the 11 and the 13, so now my biggest gear is
32 up front, 15 on the rear. So it’s not massive. The big thing to remember is how it feels so I know on that next
shift I’m in neutral. And then don’t try and pedal. (upbeat dance music) So the real test is will it shift back up off neutral gear into the cassette? Actually it does, but a 32-15
isn’t a very big gear at all so I’m not finding that useful. I may be able to stick
the 13 back on there, and just run one spacer for
the chain set on as a neutral, where I’m finding it’s not full proof, you can drop off the
bottom of the cassette, get jammed in the frame and then that’s the worst of both
worlds, I can’t pedal and it’s putting tension
back on the chain. But back at neutral I go. (hip hop music) Well, so how does it actually feel? The bike certainly feels way more active, especially braking in
corners for some reason. Actually you have to rethink about pumping and picking your lines to come out of corners fast,
you know you can’t pedal. It’s actually really impressive and a lot of fun to ride like this. There’s something about this
I reckon that really works. Well, it’s been actually
really interesting to feel different suspension
with our neutral gear, but I think it’s time to put it to test, put some times up on the board and see if it’s actually faster. (slow relaxing music) (bike tires screeching) The run with the chain,
well definitely felt fast the top proper cranking hard, definitely down in that 13 and 11. Felt rougher in the
bottom, in that rough stuff it definitely felt like the
suspension wasn’t quite sapple. However, strava tells me that the times were exactly the same. It was a short track, I’m on a Jerry bike it was less that two minutes. But to the second, the
times were exactly the same. I did make a little mistake
in the run with chain on. So actually I think I
probably could have taken a second or so off with the chain. But it’s really interesting,
I’d like to try this again on a downhill bike, on a
proper rough downhill track. Funny enough we’ve got
Val di Sole coming up, that’s the next world
cup where you probably pedal out the gate and then
that’s it through the bottom. I wonder if any downhiller should try it. I’d love to see someone do it and see how they got on with that world cup. So interesting stuff and
let’s see what happens with future designs of bikes, so can it suddenly disconnect? Is it going to happen? Who knows? If you’re interested in this test and you want to see exactly how I made this bike with a neutral gear, head over to the GMBN Tech
channel where I talk about suspension kinematics and
exactly how I made this bike and a bit more about
the suspension designs and how they’re affected by chains. Give a thumbs up for this video and don’t forget to hit our sub button.