In this installment on Manitou, we were afforded the opportunity to interview Manitou’s top suspension engineer, Ed Kwaterski. Ed was helpful in getting us some answers on how to set up a suspension fork, set up a rear suspension to work with a front fork, and more. Read on for the full details.
Twenty Nine Inches Interview With Manitou’s Tech Expert Ed Kwaterski: by Guitar Ted
Twenty Nine Inches: How long have you been tuning and designing suspension products?
Ed K: I have been involved in suspension since I graduated from Milwaukee School of Engineering in 1996. Initially, I worked on active suspension systems for the automotive industry. During this time, I began tuning motorcycle suspension with my own side-business. In 2000, an opportunity came up to go to Showa and focus on motorcycle suspension. I spent 7 years there, literally riding and tuning on the track and on public roads 15 weeks/year. The rest of the time, I worked with the factory, created suspension specs, helped sort out problems…anything to streamline the relationship between Showa and the customer. It’s pretty neat to think there are over 1 million motorcycles on the road with suspensions I had the privilege to work on, next to some of the most talented suspension engineers in the world…guys who tuned for the likes of Freddie Spencer and Mick Doohan at the heights of their racing careers. During this same time, I also grew my side business and did both tuning and kit development on Road Race, MX, Supermotard, and Street applications. It was really like having two careers going at the same time, as both jobs complemented one another. The most important thing I learned is that a vehicle needs to be developed as a system. You don’t just put “the best fork” on and expect the best result. The geometry of the bike, including front end trail, rear anti-squat, and overall weight distribution need to be understood and accounted for. I have also found that individual preferences on a given bike are mainly a result of weight distribution and how the rider reacts in the corner (how body English and application of power affects the weight distribution.)
In 2007, I sold my shop and came to Hayes Bicycle Group to focus on the Manitou suspension product line. Our time was initially spent fixing old problems, and training the team on a new product line. Now we are fully focused on developing and launching new products with an emphasis on performance, reliability, and ease of use. Personally I like it because it takes advantage of everything I’ve learned over the years technically, and adds in the challenge of working with the team here to rebuild the brand.
TNI: What makes a good damper and why?
Ed K: Clearly, the best dampers have the best frequency response. This means the damper generates force consistently and predictably regardless of size and shape of the bump. When the damper moves, it must immediately begin pumping fluid and reacting to changes in direction and velocity. That said, a lower performing shock that is carefully tuned to the bike and rider will outperform a very high end shock that is mis-applied.
TNI: Tell us the importance of sag in set up.
Ed K: The adherence to a magic sag number is a bit over rated. It is only a starting point. We achieve several things when setting sag:
First, we are setting the static geometry of the bike. On the front, this affects the trail primarily, but to a smaller degree also affects weight distribution. On the rear, it is important to set the triangle in the proper position for pedaling efficiency and traction. The frame engineers design the pivot systems to behave a certain way, and we need to complement that with proper sag settings. Not only sag, but also shock or fork length play a major role in achieving the proper geometry.
Second, we are controlling the amount of suspension available to soak up a bump, and how much is remaining to extend into a hole. Too little sag adds harshness because the bike falls into holes rather than the suspension extending to allow the wheel to follow the ground. Too much sag wastes travel needed to soak up a bump, and also allows the bike to pitch and dive more easily.
Third, and not lastly, we are starting to balance the front and rear of the bike. If one end is too stiff relative to the other end, the stiffer end will drive excess motion into the softer end. A hard tail will perform better with less front end sag than a full suspension with the same fork. Generally, it also needs more spring rate. Otherwise, the fork will absorb the bump initially, and then take a second shot (double dip) when the rear hits that bump. This is felt as a forward pitch. Also, you don’t want the bike dipping in the front with each pedal stroke. Far better to have a full suspension bike that stays level and has no pitch motion.
TNI: Tell us the difference(s) between spring and damper circuits.
Ed K: Springs hold up the bike and STORE energy. Dampers control velocity and DISSIPATE energy. The dampers control how quickly things happen. When both of these functions are optimized, there is a greatly reduced need to change the set-up for different terrain. Now, this goes way beyond sag and knob clicks. It is up to the engineer or tuner to tailor the shape of the damping curves, the bottoming characteristic, spring rate, bike geometry, etc so that this optimal setting can be reached.
Many riders like to add compression to “hold up” the bike. This is misleading and causes many riders to get that system out of balance. Neglecting systems with lock-out or platform, adding compression damping will only slow down the motion, but given enough time, equilibrium is reached where the weight balances with the spring force. Where compression can “hold up” the bike is in quick transitions or short duration events that do not allow equilibrium to be reached. (Fast corners, quick brake applies). Damping also prevents overshoot (wheel moving farther than the bump) which is critical for maximizing traction.
Lock-out or platform dampers defy the above logic a bit in regards to what dampers do. They essentially hold up the bike by stopping oil flow, and do not perform a damping function until they blow off. How these systems blow off is unique among brands. Manitou’s ABS+ blows off a preloaded shim stack. Once that shim stack starts to pass oil, it absorbs kinetic energy in proper fashion, then closes off as soon as the input forces (bumps) drop back below the blow-off point.
Manitou’s “Wrecking Crew”: From left to right: Chris Volbrecht, Test Engineer Suspension; Ed Kwaterski, Chief Engineer/PM Suspension; Shawn Cotter, Product Engineer Suspension and Wheels
TNI: Can you give our readers suspension set up 101?
Ed K: Number 1: Take care of your investment. Wipe off the forks and shock, linkages, brakes, etc. Nothing is more important to service life than keeping the seals and sliding surfaces clean. This doesn’t mean they can’t handle mud and water. Just don’t let that mud dry on between rides. Next, keep things lubricated per owner/service manual recommendations. And be aware of spring or damping kits that may be available for your product. Manitou has damper tuning kits available for ABS+, and spring rate kits for both ACT Air (Tower Expert) and MARS Air (Tower Pro). Many riders gain both control and mid-stroke plushness with a FIRMER spring kit on their MARS air system. This happens because it enable s a lighter air pressure. Now that we covered the hardware, let’s go to set-up.
Set sag to about 20% for XC, and up to 35% or so for long travel applications. This is a starting point.
On a full suspension bike, after setting sag, the rider should get on the bike in an aggressive riding position. Bounce on the bike in a controlled manner, with most force driving thru the pedals, but also keeping the arms rigid and driving maybe 15-20% of the torso weight thru the bars. Try to do this without rocking forward and backward: just smooth vertical motion. The front and rear should move downward evenly (compression), and back up evenly (rebound). If springs are unbalanced, the softer end will dip more. On the trail, this will encourage the bike to pitch over bumps, and force the rider to compensate body position.
Adjust rebound damping on both ends as soft as possible, while not bouncing off the ground, or allowing the wheel to chatter along uncontrolled. As you go tighter on rebound, the chassis will feel more controlled, but at some point, harshness will increase, and traction will diminish as the wheel can not respond quickly enough to stay in contact with the ground. Rebound is more critical than compression to be set correctly, but compression gets all the attention.
Adjust compression damping to control the chassis during fast transitions, to minimize brake dive (speed of the brake dive), soak up landings (control bottoming energy), absorb bumps in a plush manner while not allowing the wheel to move too far and lose traction.
What causes us to change some of these set-up parameters? Sag is a static condition, but we notice performance issues in the most dynamic situations. If you really push the front down in corners, shifting weight onto the front wheel, then more preload, higher spring rate, or more compression damping may be needed. Conversely, if you sit back in the corner, then a softer front end is needed to maintain the proper balance. Don’t forget, you may adjust the rear end in the opposite direction in these situations.
Hard tails need a firmer front end set-up in order to remain balanced with that rigid rear. Just don’t go to far and lose the benefits of comfort and traction that come from a suspension fork.
Above all, experiment and enjoy the features you have paid good money for. Take some notes. The Pro’s are always tweaking and testing, and this is necessary to gain set-up knowledge. You test first, and learn as a result; not so much the other way around.
TNI: Give us the differences between the Absolute Plus and the old Absolute damper. Why the change..?
Ed K: ABS+ is a shim based damper with a tapered needle adjuster. It is very responsive and very easy to tune for any application. The closed position of the needle creates a pedaling platform, with characteristics dependent upon internal shim stacks. The old Absolute was essentially a relief valve. Each click of adjustment increased the pedaling platform. The downfall is the system did not have a good setting for plushness, and going back to frequency response, it was very slow, so you could not respond properly to changes in terrain.
TNI: What are the differences between the Tower Expert and Pro models? Is it the just the air systems?
Ed K: The Expert uses ACT Air, which is an air adjusted coil spring. The Pro uses the MARS Air system, which is a lighter and plusher system. The plushness is achieved by eliminating the effect of air piston stiction, not necessarily by low spring rate. Beyond this, the Pro reduces weight even further by the use of a lighter hollow crown, internally tapered inner legs, and more use of aluminum components internally.
TNI: How does Manitou see the future of 29″er forks in the longer end of travel? Are we going to see 140mm forks? 160mm?
Ed K: We already make a 29″er version of our Dorado DH fork, so we see this segment filling out in these mid-range travel segments. Several companies already make a 140mm travel 29er.
TNI: What about a lightweight XC type short travel fork for 29″ers. Is there any room for a product like that?
Ed K: Certainly everyone wants lighter products that are still durable. We see more trends to the longer travels than the other way around. However, there are endless niche opportunities for many unique products.
TNI: Manitou went through some rough times as far as producing underwhelming forks and providing poor customer service. Why should a customer feel good about spending money on today’s Manitou product?
Ed K: We love to answer this question. Our Tech-Service Department has developed a reputation for taking care of problems quickly and without hassles. We give every caller the same attention. On the product side, we have a couple engineers who came from other suspension industries, places where the product is expected to perform for 25,000 to 100,000 miles or more without service. This long life does not come necessarily from heavy materials or high cost, but rather from paying attention to the details: cleanliness, tolerances, oil quality, workmanship, and architectures that protect themselves from the extremes of use. Manitou has added various life cycle tests, and elevated the requirements on existing tests in an effort to bring this reliability into our line up. We expect this reliability at all price points as well. This is probably the single most important factor in the ownership experience. If you need to send your suspension back for frequent tune-ups, it means you are not riding. It adds hidden costs as well. We all work very hard for our dollars, and nothing is more disappointing than taking time off, and traveling to our dream destination only to lose riding time due to equipment failures. Our mentality here is that this is unacceptable.
When Hayes Bicycle Group purchased Manitou a number of years ago, everything was broken: drawings, supplier quality, manufacturing quality, and low product expectations. These issues are all fixed now: I can not remember the last time a fork leaked. Our ABS+ damping system is very consistent and durable; every example we ship feels the same, and the technology holds up to the most severe thrashing our Dirt Jump riders can dish out. We assemble at our own factory, with great pride of workmanship. I recently returned from our Taiwan factory, and after 3 years of assembling product, I see the same faces on the line; experienced assemblers building with much higher skill levels, and an eye for quality that did not exist when I got here in late 2007. And we are not finished. We keep raising the bar; what was good last year is no longer good enough.
TNI: Some of the trends in forks like tapered steerer tubes and 15QRs are a boon to 29ers in my opinion. That is a minimal weight gain and allows for the potential of a better steering bike. I know you guys are bringing that tech to your product at some point. Is it just a matter of time before the traditional 1.125″ steerer and 9mm quick releases are gone from mountain biking?
Ed K: Actually, the increased diameter at the point of highest stress on the steer tubes has allowed Manitou to design our most recent tapered steerers to be lighter than the 1.125 steerers. It also complements the thinner walled aluminum frames and use of carbon fiber on both road and MTB applications. As for axles, many of us in the industry feel that 9mm quick release will happily go by the wayside, as we enjoy the greater safety and higher performance of the 15mm systems. Cost will likely keep both 9mmQR and 1.125” technology on mountain bikes at some level for the foreseeable future, however more and more just on the lowest cost product.
Twenty Nine Inches would like to thank Ed Kwaterski, and Manitou’s Rich Travis for getting this interview off the ground. Look for more on the Tower forks coming up this spring.
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