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The after-work bike traffic is rolling by the Grünwalder Bridge near Munich. We've just guided Fabian and his friend Johannes from the trail to the BIKE bus and exchanged a few words when our suspension expert Florian Ohnesorg pulls out his mobile phone and taps away. How rude is that? Does he have better things to do than turn his attention to their bikes? Not at all. Florian is completely focussed.
"The right app is the second most important tool after the shock pump," he grins and continues to enter key data on suspension elements and surface, riding style and weight into the smartphone. One last tap and it's clear what pressure and how many damper clicks Fabian's stylish Santa Cruz should be set to as standard. "Okay," he says, "we've already got a good starting position. And now let's take a closer look."
Fabian, a muscular guy of almost 100 kilos, climbs onto his bike to check the negative suspension travel and gets off again very, very carefully so as not to mess up the measurement. Expert Florian uses a metre rule to measure how far the suspension has sagged under its owner. He then checks the pressure of the suspension elements with his damper pump - and is immediately disappointed: "Sometimes people come into my shop whose suspension is practically dead as a doornail. But here," he scratches his head, "I don't have to do much. The pressure fits so far."
Second check: rebound and compression damping. The rear end is in the right direction, but Ohnesorg finally finds what he is looking for in the fork. "That can't have felt good. 80 psi on the fork, almost 100 kilos of rider weight and an almost open rebound! That's completely under-damped. Can I have a go?" he asks, first turning the red rebound knob all the way to the right and then very carefully, click by click, back a little. "That should be fine," he says with satisfaction and lets Fabian and his Santa Cruz set off on the rest of the tour.
Chassis adjustment used to be: new spring, conversion and all over again
In the early years of full-suspension biking, suspension adjustment was much more complex than it is today: instead of relatively large-volume air chambers, springs made of steel or elastomers determined the spring rate. Instead of oil-filled cartridges with various pistons, valves and clicking adjusting wheels, the internal friction of the system sometimes did the damper job. To adjust the spring rate to the rider, a replacement spring was often required - which was not always easy to obtain, but with only six to eight centimetres of spring travel, bikers had nothing to give away. The result: poor performance and a lot of tinkering. Today, steel or titanium springs are used almost exclusively on long-travel downhill bikes for specialists. The current suspension elements in the fork and rear triangle are much more user-friendly. Special tools and special greases have been replaced by a pump and app or table. A little pumping, a little turning, that works even without rubber gloves.
Florian, the suspension whisperer, only had to deal with a classic screwdriver topic on the second bike in our small sample: Johannes Schenk pushed his Scott Spark, a stylish marathon fully, to the starting line. Suspension check: So far everything is fine, the setting is suitable for uphill use. The fact that the fork cannot be locked out from the handlebars turns out to be a problem of insufficient tension on the Bowden cable. Two turns of a knurled screw and the problem is solved.
However, despite all the progress, suspension adjustment is not trivial, says head mechanic Ohnesorg: "The manufacturer's specifications are only of limited use because they do not take weight distribution and riding style into account." In addition, the manufacturers develop their suspension elements for a fictitious, medium-weight standard customer. The adjustment range of the suspension and damper is not sufficient for everyone, which is why some Specialists customise the internals of the suspension elements. "For people of normal weight in a wide range, however, tuning with part replacement of the suspension element is rather pointless," says Ohnesorg, who also offers this service himself. "You can only really tune a suspension perfectly for a specific track or even just one section of it anyway. That's something for top athletes. Or for particularly light and heavy riders."
Katharina Brenner and her friend Elias Bluhm roll up as if on command. Katharina moves heavy equipment, a Scott Ransom with 170 millimetres of suspension travel. She herself is rather light and petite. "Okay, maybe we're not ideal for your project," says Elias. "I used to race and now work part-time in a bike shop. So of course I'm a bit more familiar with the subject and look after Kathi's equipment."
A year ago, Katharina discovered the bike parks for herself, and even though the adjustment range of the suspension elements is still sufficient for her body weight, the setup is an ongoing issue. It's all about the characteristic curve of the fork and a compression setting that conserves her arm strength on bumpy sections but frees up suspension travel on flat landings. This doesn't seem to be easy, as Florian and Elias spend around 20 minutes discussing additional air chambers, electronic features and small mechanical parts. At one point, Katharina turns her face into the remaining sunshine, smiling with amusement. In the end, all the tips are changed, the bike rolls to the river unchanged, and Florian realises that a suspension setup is not just a technical issue: "I would have changed something on the rear triangle. But that would have been rather uncool psychologically."
Simone Lohbrunner owes her e-MTB to a temporary move from the Allgäu to the Bavarian Forest. The Specialized Levo Comp with 160 millimetres of suspension travel was her bike of choice for more flow in the forest. She bought the bike online, but set it up herself with a friend. The pro's tip: "A little more sag, a little less damping. Otherwise it's fine."
I've been cycling sportily for ages. I bought the E-MTB to ride more trails in hilly terrain or to take flowing lines in the bike park. I never felt the need to change the suspension much. - Simone Lohbrunner, e-biker
Martin Leischnig has been a biker since 1995. He made the switch to e-bikes four years ago. The second-hand Cube Stereo with 160 millimetres of suspension travel is his second bike with electric muscle. It not only rolls over the rooty Isar trails, but also serves as a towing vehicle for a child trailer. With so many different uses and plenty of travel anyway, Martin never bothered to perfect the setup.
The previous owner was about my height and weight. That saved me the work of adjusting the suspension. - Martin Leischnig, e-biker
Damper pump: tool and measuring device in one
Simply indispensable: A special pump for the air suspension elements not only creates pressures in excess of 20 bar, but also helps with measuring and finely dosed deflation. For occasional use, a mid-priced model such as the backpack-compatible Topeak Pocketshock DXG (50 euros) is sufficient. Pumps with an analogue pressure display are no less precise than models with a digital display, but are somewhat more difficult to read. Angle adapters also make unfavourably positioned valves accessible. Air always hisses out when the pump is unscrewed. It comes from the pump hose. When measuring the air pressure without pumping up, large-volume air forks lose up to 5 psi according to the experience of the BIKE test laboratory. Small rear suspension elements with pressures of over 300 psi lose a maximum of around 10 psi. There is no pressure loss when inflating.
Quarq Shockwiz: square, practical, good
Complex suspension elements, especially those with separate high and low-speed damping, are almost impossible to adjust perfectly using a popometer. The Quarq Shockwiz with accompanying app makes things easier. The postage stamp-sized box is attached to the fork or shock absorber with cable ties and connected to the air chamber. During a test ride, the box then measures the pressure and speed of the pressure changes and derives data on the spring travel used and damper settings. The app translates the recorded data into precise recommendations for different riding styles and suspension elements - right down to the specific number of clicks on the shock. The price is steep for hobby bikers, but some dealers lend out the magic box. About 350 euros from Sram.
Suspension tuner
If the demands on the suspension are greater than the standard adjustment range, specialised suspension tuners such as the companies listed below (not exhaustive) can help.
- Bike Performance, Dresden
- MRC Trading GmbH, Stegaurach
- Ultravelo, Lenggries
- R-Suspension, Rudolstadt
- Flow Bikes, Ingenried
- Bicycle chassis, Tübingen
- HelmchenTuned, Düren
- Marcus Klausmann, Mahlberg
How to set up your suspension fork and shock optimally
Simple to flow: the order counts. In principle, the process is identical for the fork and shock absorber. The compression and rebound characteristics should also harmonise on the front and rear wheels.
Starting position
The sliding bushes of the suspension elements are lubricated because the bike was ridden briefly or turned upside down for ten minutes and then compressed. All damper controls are open (turned anti-clockwise). The air pressure is set according to the manufacturer's specifications or left at the current value.
Sag-Check
In the decisive riding position (i.e. standing in the centre of the bike for trail bikes to enduro bikes), you check how much of the specified suspension travel is being used by the weight of the rider plus luggage and the mass of the bike alone. The O-rings or a temporarily attached cable tie often serve this purpose. The best way to do this is with someone holding the bike securely and pushing the rings down to the scraper when the riding position is assumed. Alone and leaning against the wall also works. Then carefully dismount and measure the suspension travel used.
Adjust air pressure, lap 1
How much sag is right depends on the total suspension travel and the riding style. The more suspension travel, the more sag is appropriate. On the fork, it is usually about five per cent less than on the shock. Basic values are 15 to 20 per cent at the front for cross-country suspension and around 25 to 30 per cent in the enduro sector. The tables on many forks are a guide to the air pressure. Tables would be pointless on the rear shock, as the rear triangles have different leverage ratios. The arithmetic operation is simple: Sag in per cent is equal to the suspension travel used divided by the total suspension travel times 100. Is the air pressure set? Then unscrew the pump and compress thoroughly several times. This adjusts the pressure in the negative air chamber. The pressure in the positive air chamber - the actual spring - changes slightly as a result.
Adjust air pressure, round 2
The sag can now be finalised. Sit on the bike again and measure the suspension travel used. Depressurise or pump up if necessary.
Setting the rebound damping
The rebound is largely independent of the riding style and only needs to match the air pressure. With Fox and Rockshox, it is usually adjusted with a red knob. The rebound damping slows down the rebound so that the bike does not bounce like a bouncy ball after a large obstacle. At the same time, the wheel should ideally rebound so quickly that the suspension travel is available again at the next obstacle. The easiest way to find the correct setting is to follow the manufacturer's instructions. Rockshox reveals the appropriate rebound setting for the respective air pressure in the Trailhead app, Fox hides the information on the website under "Help" in the operating instructions or prints it directly on the fork. The reference point for the information given there, such as "minus 14", is the number of clicks required to open the damping again (anti-clockwise) from the fully closed state. Without the corresponding information, you compress the fork or rear triangle as much as possible with your body weight and let go as quickly as possible. The wheel should lift minimally at most when rebounding. Rule of thumb for the rebound: as fast as possible, as slow as necessary. The damper oil becomes viscous when it is very cold. It then makes sense to open the rebound and compression stages further.
Setting the compression stage
The correct compression damping has something to do with personal preference. On most forks and shocks, a blue knob or lever is responsible for this. Expensive suspension elements have one control for the high-speed and one for the low-speed compression damping. However, if there is only one control, it is usually for the low-speed compression stage. It regulates the compression speed and is independent of the rider's weight. Too little compression damping can lead to the suspension sagging too quickly on steps or berms or feeling nervous when pedalling. Too much compression damping ruins the response behaviour. It's a game of trial and error. Cross-country riders will tend to adjust their suspension more smoothly than touring riders with lots of root passages. A relatively open compression damping in combination with the platform setting available on many suspension elements for pedalling-intensive passages is a good starting position.
Chassis Basic vocabulary
Pressure stage
Compression damping regulates the speed at which the fork or rear suspension compresses. On some models, it can be adjusted separately for fast (high-speed) impacts such as landings and large obstacles and slow forces (low-speed) such as braking or pedalling forces.
Characteristic curve, progression
The characteristic curve indicates how the spring element behaves under increasing load. To put it simply: if the fork sinks in one centimetre with a load of ten kilos, two centimetres with 20 kilos and five centimetres with 50 kilos, its characteristic curve is a straight line or "linear". If it reacts in the same way at the beginning, but needs, for example, 70 kilos to compress five centimetres and 180 kilos for ten centimetres of suspension travel, its characteristic curve is "progressive". If both are at the limit with the same load, the progressive fork will react more sensitively in the area of smaller obstacles, but utilise less suspension travel for medium to large impacts.
Say
For once, not an abbreviation, but simply the English word for "lowering". This refers to the suspension travel that is utilised solely by the body weight of the person standing or sitting statically on the bike. The sag is the starting point for suspension tuning.
Token
Can mean all sorts of things in English, but in the field of suspension it refers to thick plastic discs that can be inserted into the air chamber of the fork and damper by non-experts to reduce the air volume and thus make the characteristic curve more progressive. They are also called volume spacers.
Rebound
The rebound damping slows down the speed at which the compressed (air or steel) spring expands again. If there is a separate high-speed rebound stage, it slows down the rebound after full compression, as this is when the greatest restoring force acts.
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