Talking Telemetry and Downhill Bike Setup with Giant's Dave Garland

While it can look like controlled chaos from the outside, World Cup downhill racing is often a game of millimeters, tenths of seconds, and the non-stop search for the fastest setup. Using telemetry, an electronic automated system that collects data, to get as close as possible to that elusive perfect setup isn't a new thing, but Giant team mechanic Dave Garland has put together his own compact system to help Elliot Jackson tune his Giant Glory Advanced. More specifically, to dial in Elliot's bike to provide as much grip as possible.

Pinkbike's Ross Bell sat down with Garland at the Leogang World Cup to get a closer look at Elliot's bike, and to find out exactly what all those wires and that black box actually do.

''This project really started in my mind as far back as 2008 when I began looking closely at componentry, what each component on the bike does, and its relation to the next part that does a job close to it,'' Garland explained while emphasizing that each part of the bike affects other parts. Understanding how those components relate to one another, and what to change to eek out those few tenths, requires more than just a deft touch and good rider feedback. ''This weekend is the perfect example. Don't quote me on it, but I think you've got fifteen people on the same second,'' he said of the competition at Leogang. ''There's no way on earth that you can guess an adjustment and make that closer. You have to go to something that tells you.''

And that something is a computer.




Garland has mounted a host of compact sensors on Elliot's Glory; there's a sensor that measures rear axle position (a more time efficient approach than having it on the shock, he says), a wheel lock-up sensor that can also measure wheel speed, sensors for fore/aft and lateral movement, and also brake pressure sensors. All of these are bespoke units manufactured to Garland's specs specifically for downhill racing

''I've been lucky to be involved in pretty high-level motorsport awhile back where some type of telemetry was used, but it was impossible for bikes because it was far too big and had a lot of information that you don't really need. So, skip forward to two and a half, almost three years ago now, and I started trying to find ways to measure what I needed to measure in order to make a rider go fast. What you see is pretty much the finished article. There are a few updates, and the great thing is, with this system I can, with my software engineers, actually update it on an almost weekly basis based on what I've learned. That's a great advantage.''




When someone mentions telemetry, you probably think of suspension setup and massive boxes strapped to downtubes, probably with a rat's nest of wires coming out of it. Garland's system is quite clean, though, and it measures much more than fork and shock action. ''You might see a few other systems being used right now, and they're largely suspension-based, which is great because suspension has to work properly. But downhill is such a specific sport; there are no constants, and everything is changing all the time. I've found in recent years that people always seem to point the finger at suspension as the cause of characteristic problems like flat tires or over-working components that go to failure. Yes, suspension has to do its job, but it's really just one part of the picture in getting a downhill bike to work properly.''


''Because, as everyone knows, if you're braking hard through a corner, the bike isn't in its most efficient geometry to get you through a corner.'' Defined braking zones aren't just for motorsport, it seems.





And speaking of braking, brake pressure sensors don't lie when it comes to when Elliot is pulling the levers. ''During testing in the winter, what we found, because a downhill rider needs to ride a downhill bike as much as he can, is that when your fingers are covering the brake levers, without you even knowing it, you're pulling the brakes sometimes. It's due to muscle memory.'' This testing revealed values of 20, 30, 40, 50 bar (290 - 725 PSI) of pressure when riders were saying they weren't braking, simply because their fingers were on the levers and it was a subconscious action. More braking equals less speed, of course, and vice versa, so have no doubts that the team has been working on this one.

There is also a rear axle sensor that measures the wheel's position, something that Garland says is a more time effective way of evaluating suspension action than mounting a data acquisition unit directly on the Glory's shock. Garland pays special attention to front and rear ride height - where the fork and shock are sitting in their stroke. ''We can tell whether that's equal, and it does need to be equal all the time in order for the bike to be balanced,'' he says, with an unbalanced bike asking its pilot to shift their weight distribution around too much.

''Downhill bikes are at the point where if it's correct and everything else is correct with your body position on the bike, you're steering a ship. You're no longer very animated on the bike. You can see the riders who've got that worked out because they're very still, and they don't have to make a bodily correction very often to get the bike to do what they want it to.''




Garland believes that equal balance produces grip, and grip is the key to going fast: ''The single most important job you have to produce to make a rider confident is grip; everything is to give the rider as much grip as possible and to make sure that grip is very equal front to rear.''

A World Cup race weekend is a fairly condensed event with limited time available for practice and testing, so one of Garland's main focus with his telemetry setup is to have an effective system that produces easy to understand metrics. A racer is likely to only get eight or nine runs, at most, during practice, which means that the data has to be simple and clear to understand. ''This is about taking the guesswork out of it; it's not going to solve every problem, but it helps you go in the right direction very, very quickly,'' he says.

What shows up on the computer screen are easy to read metrics with relatable stats laid over other relevant data so that a rider and mechanic can easily see how things interact and the knock-on effect. ''A lot of it is down to flex in each component. I mean, the wheel is really important for producing corner speed; if that thing is really, really stiff, then you're expecting the tire to do all of the work. Well, it can't do it all; it has to have its partner to help it,'' Garland asserts to highlight the connection between components. ''Lateral and vertical movement; I've been doing this kind of tuning since the late-90s. [Spoke tension] is one of the most important adjustments you can make.''




But Garland doesn't blindly trust the computer, however, as what the rider is feeling being just as important: ''We have camera footage to go by as well, and the most important value is what the rider tells you. As long as you can draw a picture between all these different parameters, then you can quickly and effectively work out where you need to go.''

Despite much of the field turning to 29ers, Giant's downhill bikes all roll on 27.5'' wheels, something that probably won't change during this season. Garland is still looking forward to getting the most out of the current platform using his telemetry system, though, and he believes that there's still plenty of room for improvement: ''These bikes, 650s, in my mind they're being sold a little short because we're really only in the second evolution of these bikes. You know, 26ers probably went through fifteen evolutions to get to where they were four or five years ago. Now we have 650B bikes that are well capable of doing what a 29er does. Obviously, 29ers makes it slightly easier but, for me, these bikes are still, and will be in the future, very competitive bikes. We've seen that this weekend,'' he summed up, citing Gwin's winning run on 27.5'' wheels.