The Engineer Speaks: 2012 Manitou Tower Pro
An Interview with Manitou’s Ed Kwaterski- by Grannygear

There were enough changes in the 2012 Manitou Tower Pro forks to delve in a bit deeper, and, there are enough tuning options as to be maybe a bit confusing.  So, we went right to the source at Manitou and tossed out some questions to the Grand Poobah of engineering, Ed Kwaterski.  Read on, dear readers, read on.

TNI -So, Ed, take us quickly through the 2012 Tower Pro 29″er fork we have on test at TNI.com.  What has changed and what stayed the same over the 2011 model, then we will unpack things a bit more in detail.

Ed K: Well, the big news for 2012 is the new casting design, 1.5 tapered steer, and our new QR15 Hexlock axle.  We’ve updated the styling while reducing weight and increasing strength in the casting on both 9mm and QR15 versions.  We have a new crown for our 1.5 Tapered steer.  Internally we do not have major changes, however Manitou never leaves well enough alone and always has minor upgrades to improve service life or ride performance.  All Tower Pro models come standard with our FIRM ride kit spring, which we found to be more appropriate on 29″er bikes.

TNI - Finally…tapered steerer and 15 mm through axle!  That has to feel good being able to offer that to consumers!  Personally I would not buy a 29″er fork at 100mm or longer that was not tapered and, except for the OS28 9mm interface that Specialized uses, 15mm through axles are now the defacto standard for XC and Trail Bikes.

Ed K: Yes, it’s always nice to get another product off the plate and out into the market.  So far the feedback has been extremely positive for the Hexlock Axle.

TNI - The QR15 system that you offer kept the Hex Lock axle and is a unique set-up.  Tell us about that and why you went to all the trouble to keep Hex Lock.

Ed K: One of the great legacy technologies we acquired from the prior Answer-Manitou ownership is the Hexlock patent.  When a fork is loaded in torsion, the legs try to rotate about the axle.  A well designed clamp system and correct clamp torque on a round axle can withstand quite a bit of this torsion, but will eventually slip. Our original Hexlock axle completely eliminates any rotation due to torsion of the fork assembly, and reduces sensitivity to tolerances and pinch bolt torques.  All of that aside, riders today expect not to need any tools to install their wheels.  When time came to launch QR15 into our product line, there was some push internally to make it easy and low risk on ourselves by using an existing design already accepted by the market.  Our Engineering team actually fought to pursue this new technology, and it took a few iterations to get the ease of use we were looking for before the rest of the group became believers. In simplest terms, we incorporated a ¼ turn fastener into our hex axle.  To install it, the user simply opens the lever, rotate the handle until it clicks, and with laser etched instruction (on the axle diameter) facing up towards the crown, slide it into the drop-outs.  Then rotate the lever clockwise 90 degrees, and flip it closed.  Properly installed, the lever will always be pointing upward and parallel to the lower fork legs.

TNI - The casting of the new Tower stands out as different at the arch as well.  It reminds me of a Klingon Bird of Prey (semi-obscure Star Trek reference here).  You guys stayed with the reverse arch though.

Ed K: That is correct; our arch can be shorter than other designs because it is behind the peak of the tire (behind axle centerline), which contributes to increased stiffness.  Just as importantly, this is a very recognizable Manitou attribute that sets our product apart from everyone else.

TNI - This fork cannot be travel adjusted, correct?

Ed K: That is correct.  The MARS spring system is just too involved to allow this, and our higher end forks use specific leg lengths for each travel to help reduce weight.

TNI - Crown offset is a bit more aggressive than some of the competition at 48mm.  So you are a ‘tweener’ here…not the 51mm of a G2 Trek/Fisher approach but more than others at 44mm-46mm.  Mama bear approach or?

Ed K: The 48mm offset increases toe clearance vs the 44 and 46mm forks, and also reduces trail which makes the bike more nimble.  Manitou has used this value for a long time.  I seem to remember one of the old Manitou guys telling me this was first used with Trek before they went to the G2 geometry.

TNI - Internally, my fork was built per my needs with spring rate and shim stack, but that is something any buyer can do…customize the fork for his or her needs.  What are the options and how does that work?   Can it be ordered with a certain configuration or is this something that needs to be done post-sale?

Ed K: Prospective buyers should know that Manitou forks are the most customizable forks sold today.  We sell “ride kits” which are alternate spring rates for those forks which use a coil as part of the positive spring system (ACT Air in Tower Expert, MARS Air in Tower Pro).  In addition to this, we have an ABS+ Tuning Kit which comes complete with a book of shim stacks and dyno curves to enable virtually any type of compression damping performance you could want.  The kit is designed for shops, as it has enough parts to tune and repair about 10 ABS+ dampers.  Owners should first talk to their dealers, but if the dealer is unfamiliar, our Tech department can help out with the correct recommendations and part numbers.

Manitou is very customer centric and accessible.  Dealers and consumers will get a friendly voice and real advice on how to get the most from their products.  Even I will frequently get directly involved with solving issues and giving advice. Most recently this resulted in a special Clydesdale spring for the Tower Pro 120 because our biggest riders were not being adequately covered with our standard range of springs. This is so recent the first samples are on my desk now, and the rider who originally contacted us will get his shortly following some rate testing in the lab.  We listen to our customers, and even if it takes longer than either of us would like, eventually this input makes its way into the product.

TNI - Can we talk about the proper way to approach tuning on a Tower Pro?  The coil spring has a relationship with the air chamber that is a bit different than an all air sprung fork, yes?

Ed K: The Tower Pro uses our MARS Air system.  MARS air uses a small coil spring in series with an air spring.  The coil eliminates all felt stiction created by the seals in the air spring.  But more than that, the properly tuned MARS system has 3 distinct rate curves over the full travel.  The initial rate will be determined by the coil spring.  Then from about sag to 70% of travel, the rate curve will flatten out as both the coil and air spring work together.  Then late in the stroke, the air spring will dominate and ramps up in a progressive fashion.  In other words, the entire range of stroke can be optimally tuned without sacrificing the other areas.  A full air system, for example, trades off mid-stroke vs bottoming feel depending on the air volume used.  A larger volume will provide a more linear feel though-out the mid-stroke, but lacks bottoming control.

Tuning the MARS Air requires a couple of pieces of information:

1.  If you can not reach desired sag regardless of air pressure, then you need a firmer coil rate.

2.  Too much air pressure will create a distinct spike in the mid stroke because the air spring is too dominate over the coil.  If this happens, you will want to install a higher rate coil.  In a (model year 2012) Tower Pro, which come stock with a “Firm” coil, this will occur around 120psi.  We call out 110psi MAX in the Tower Pro, but there is some margin in that number.  As long as you know what to look for with the above two points, you can creep up towards that 120psi.

Now, if you have sag set to a value you are happy with (maybe 25%, for example), but find yourself bottoming too often, you can increase the bottoming resistance by adding about 5cc of oil to the top of your air piston.  (Let the air out first before unthreading the cap!!)  This will make the last portion of travel more progressive.

Another tip:  If you have too much brake dive, you have a few choices.  Add another 5-10psi (sag percentage is only a starting point anyway), try a firmer rate coil, add that 5cc of oil on the air piston, or add a click or two on your ABS+ compression adjuster.

Keep in mind, the spring determines HOW MUCH brake dive, the ABS+ compression system determines HOW FAST the brake dive.  The reason people tend to use compression damping is that when the fork dives more slowly, they naturally adjust body position more easily to compensate for that dive, often without even realizing it.  The downside is they often sacrifice ride quality in the process.

TNI - Anything else we need to know?  Pricing, etc?

Ed K: Tower Pro is now available in a 140mm version.  Feedback from our Pro test riders (our HTP crew) has been extremely positive on this.  Stiffness has been compared favorably with larger diameter competitors, and the smooth function can’t be beat.

If you haven’t tried out a Manitou fork in awhile, give it a shot, we really believe you’ll be impressed.

Pricing in USD is as follows:

Tower Pro 9mm 1 1/8 Alloy Steer MSRP = $499.99

Tower Pro 9mm, 1.5 Taper Steer MSRP = $514.99

Tower Pro QR15 1 1/8 Alloy Steer MSRP = $534.99

Tower Pro QR15, 1.5 Taper Steer MSRP = $549.99

Tower Expert 9mm, 1 1/8 Alloy Steer MSRP = $399.99

All forks can be custom tuned, and all are MILO (remote) compatible.

Twenty Nine Inches would like to thank Manitou/ Ed Kwaterski for the opportunity to do this interview.