Bicycle Base Tunes | More Than A Supporting Role
A look into bicycle base tunes with Sram’s Torben Borrowy...
A look into bicycle base tunes with Sram’s Torben Borrowy...
From Dirt Issue 124 - June 2012
Words by Steve Jones. Photos by Steve Jones.
Not much more than a tin full of oil and washers but never have so many done so little for so much. Opinions will vary. Being the heart and soul of the party comes with it overwhelming responsibility, but rear shock absorbers carry the burden of weight and expectancy of thousands of riders worldwide. Opinions will vary, that’s why it’s big business. Everyone loves damper chat.
Fortunately we don’t get as many shitters as we used to, the bikes we get are largely fairly good in suspension design and with the correct shock tune. It’s rare that a howler of a bike comes through the door in need of urgent shock therapy. Yes it does happen, but given the wide range of dampers/tunes offered, particularly by RockShox and Fox, it’s surprising that it happens at all. And let’s face it, over a certain price–point tailor made dampers should come in the price of a bike.
Opinions vary, different riders will have an alternative take on things depending on many variables, environmental, physical or skill based. Even a mood will alter how you weight/load your bike on a certain day. Some product managers (PM’s) might have bad days too, yet ultimately it’s that person’s personal preference, together with his perception of who and how he feels will be riding the bike and under what conditions, that ultimately determines what type of tin you have.
Largely they do a grand job, more often than not they get it on the nail leaving us muppets to drive it home. Ideally however a shock absorber should allow you movement above and below a mean setting, allowing you softer for wet days and harder for dry days. Maybe it’s unfair to expect a PM to make everyone happy, they simply do the job of getting a base tune, but that certainly doesn’t mean it will be the correct one for you. For many riders the first port of call after purchasing a bike will be a call to one of the many shock tuners. This is especially true for trail bikes that are sometimes weak on the compression tuning compared to downhill bikes.
When it goes seriously wrong or if a product manager can’t get it right it goes back to someone like SRAM’s Torben Borrowy. We were lucky to catch up with Torben when he had his tins out. We had a look inside and he prepped us some gems.>>
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GENERAL SHOCK TUNE
Dirt: Clearly there are extremes of body shapes and riders are frequently outside the 12.5 stone (175lbs/79kg) of the average Euro male. Many bike companies fit a shock they say will cater for riders between 100lb and 250lb. Do you believe a shock can work at its best within this large range?
Torben Borrowy: In general rear shocks work perfectly within a wide range and can be fine–tuned with the adjustments of the rebound and compression clickers, and the spring rate (change of the coil spring or adjustment of the air pressure). On the extreme ends of the weight range mentioned above, you compromise a bit of performance but the compromise is still hard to notice.
Explain why the optimum shock for a bike might (assuming average rider weights) be right for some riders yet too hard or too soft for others?
This is where riding style and the terrain you ride in comes into play. If you have a very dynamic or active riding style and blasting through berms is your deal you want more support on the low speed compression damping, if you are looking for the maximum comfort you might find such a setting too harsh. On the rebound side of things it also makes a difference if you are riding on a man–made hard–pack soils where you want the suspension to feel very settled, while a natural, rocky alpine trail requires a more active or lively setting to adjust to the bump frequencies. Also more aggressive riders benefit from more ramp–up in the spring rate while a linear curve offers more comfort.
Terrain, rider style, come on Torben! Surely there are enough dials on a modern shock to compensate for different people?
That is correct. The range of adjustments is pretty big and on high–end shocks you can find multiple ways to fine–tune your shock without having to open it. It is always key to have the correct base tune for the bike. The number of adjusters on your shock should be very minimal if you just want to swing a leg over your bike and ride, if you want to fine–tune your shock and spend some time finding the optimal set–up you should go for the full package of adjustment options.
I guess the message here is that riders buying after–market should buy correct to begin with right? How should they go about this?
As mentioned above, the right base tune for your bike is key. The RockShox dealer should be able to help out here. He can always rely the knowledge of the SRAM Tech Centre and complicated cases will find their way to our computers.
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LAPIERRE ZESTY – Torben tunes up some beauties
Given the wide range of standard tune shocks available we were fortunate that Torben could send us a few shocks to get an idea of suitability for a Lapierre Zesty we had on test. The earlier version of this bike was a classic example of a one that needed more support and harder compression tuning for some riders.
Dirt: OK so this shock for the Zesty feature in the magazine for example is set for what range of rider weight? What changes might I be looking to do (internal or external) to the shock for a heavier rider?
Torben: The shock pretty much is set up for a rider weight from 70kg to around 100kg (150lb–220lb). Heavier riders should be good, lighter rider might ask for a faster rebound. This would be a change of the rebound shim stack.
Can you decide what shock suits a bike simply by sitting in an office?
By looking at graphs and numbers on the computer I’m able to find an ideal point to start at, but real world testing is always necessary. Numbers and charts don’t tell you about rider–weight distribution on the bike, tyres, forks and other variables that influence rear suspension characteristics.
Balancing the system then. I’m going to run a RockShox Revelation World Cup up front. How comparable will it be in spring/damping terms to the Monarch Plus?
Perfect match. The Monarch Plus is a very good match for a Revelation bike.
The old Zesty design was a tricky one to manage the travel, you made me a custom tune with very heavy compression yet it seemed to control the travel far better. The new design is more progressive with an easily understandable stroke correct?
The engineers at Lapierre put a lot of thinking into the new Zesty platform. The position on the bike and also the geometry changed quite a bit. The leverage ratios did also. Since you have a very hard–on–the–suspension style of riding we have to think differently about your set–up. The average rider would probably prefer a softer and more linear set–up like the stock one we’ve developed for this bike.
OK basics. The bike comes standard with a FOX Float RP2 HV Boost Valve 200x57 for OST+. You’ve given me two shocks here. One will be a base setting shock right? Which one and why?
Based on the information I have from previous test sessions with Lapierre I’ve built an ‘L’ compression tune and a slightly reduced high volume air can. The second shock comes with a medium set–up. This gives you a good comparison and also might suit your riding style.
That’s right. Fox is working different with their tunes, so they have different descriptions.
Are they standard units?
Yes, both are standard tunes. If both tunes wouldn’t work at all, we are going down the custom path.
How do you work out the tunes?
The individual standard tunes for the Monarch Plus have been worked out in our test lab in Colorado Springs based on the damping curves and data of the Vivid shocks.
Do you have base settings, that’s enough surely?
The three base setting we have cover a pretty wide range. Sometimes the frame engineer or product manager is looking for something very specific for their bike design, that’s when we start working on a custom tune.
Do you believe there is enough variation on the dials on standard shocks (assuming average rider weight) to accommodate ‘rider style’ as some tuners say?
Most of the time the frame and its shock comes as one system. If the frame engineer or product manager takes full advantage of the variety of parameters and work out the right tune, the shock should be pretty much perfect for a given bike and would not need additional tuning.
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THE BASICS OF A MONARCH PLUS
Let’s take a look at the variation of the Monarch Plus damper.
190x51/200x51/200x57/216x63/222x66. Shim stacks: Three tunes for compression, low, medium, high. Three tunes for rebound, low, medium, high.
Outline the component differences between light/medium/high rebound.
Thickness, diameter, and number of the shims.
What are the component differences between light/medium/high compression?
Same again. A normal can is needed for bikes with a falling rate rear suspension ratio. A high volume can is needed for bikes with linear or rising rate. The air can size is very important. Too small and you won’t reach your travel, too large and you are flying through the travel. This is usually the first thing you set up when you get a bike to test shocks on.
What makes this shock smoother than stock?
A number of finishing touches will.
Dirt: With who do you feel the responsibility lies to get it right? The rider/the tuner/designer/product manager? 5K bikes for example should surely be ‘tailor made’?
Torben: The responsibility is in the hands of the product manager of the bike brand. It’s his bike and he gets to choose the right componentry.
Why at Sram test days do I get a better feeling from the shocks compared to those that reach me via a bike brought in for test though?
Look at the big number of different bike models out there. It still is a challenge to work on every model and the available time you have between model changes can be short, so a product manager of a bike brand might not be in the position to choose the perfect tune. We do our best to change that and help as much as we can.
Some bikes, no matter how much damper changes you make, it is still a shit bike right?
For sure there are some challenging leverage ratio curves, but I have not been at the point where we had to give up. Of course some designs are better than others.
How many companies actually go through the process of trying different tunes?
Lots, and the number is increasing fast.
Some companies have riders who test many shocks for their bikes before the final spec. Is it simply a balance between the theory, the test riders then and the product manager’s opinion of what tune would suit the rider who will own that bike?
You can even get ‘performance tuning’ on Monarchs from other companies! Can I not get that off you guys?
Customizing through our channels is a bit of a challenge due to the way our organization is set up. The in–house suspension department is flat–out busy with the OEM work and we simply don’t have the infrastructure to offer individual tuning for the consumer. This is where our partners and distributors come into play.
That last question was hinting at the fact that there are companies that claim to offer improved performance over standard Monarch or other stock dampers. I believe that even a standard shock properly prepped offers sufficiently solid performance for most of us muppets. Considering the talk that goes on about shocks it’s pretty simple really, there might well be differences between companies with tunes, but our stock L/M ‘with finishing touches’ was perfectly good. In fact it was more than that.
Obviously we are in a privileged position to be able to try out so many shocks and lucky that with the Lapierre bikes the product managers know their tins and linkages. I guess the message here is get some good advice, the good thing with the many of today’s fully adjustable units is that they allow for experimenting.