Interview with Paul Lew, Director of Technology and Innovation at Reynolds Cycling, LLC on their MT29 wheels: By c_g

In the context of our Carbon wheel experiment we at TNI Europe are reviewing a set of REYNOLDS MT29 wheels. For the intro see here. These wheels are an interesting combination of a wide rim (29 mm outside and 21 inside), a low spoke count (24 holes) and light as can be spokes (DT-Revolution , 2 x laced) – a combination not seen all that often and reason enough to approach REYNOLDS development apartment to find out the WHYs and WHATs behind those wheels. So here comes the interview for you to read.

Twenty Nine Inches: Can you give me a small background to REYNOLDS cycling and what you do?.

Paul Lew: Wheels are all we do. In the past Reynolds has manufactured carbon tubing, forks, handlebars, and wheels. For the last 4 years we have focused only on wheels. A few years ago we looked internally at our passion, and at our engineering focus, and it was wheels. We know carbon, and we know wheels. We have developed an extensive knowledge base from the road side gathering knowledge from Grand Tour European professional cyclists (Reynolds is in their third year with AG2R La Mondiale Professional Cycling Team).

TNI: And with your background in road cycling you diversified into MTB wheels. What were your goals?

PL: When we entered the MTB market we knew that many of the basic principles of wheel performance would be similar. While there are similarities, we have had to create an entirely new set of requirements for MTB wheel performance. Because our heritage started in road, we didn’t feel like we had to follow any particular MTB recipe, and so we started with a clean sheet of paper. The MTB designs have been performance based, not necessarily traditional. We have created an optimized wheel system—optimized based upon the performance requirements that we defined. While it is common for performance requirements to typically include stiffness, strength, durability, and light weight, as the wheel designers, and manufacturers we have the opportunity to prioritize these primary requirements.

TNI: Ride tests in real world conditions are great (and often good fun for us testers :)), but looking at your road wheels you also take a more scientific approach to testing. There is a lot of aerodynamic considerations going into these. What specific tests does REYNOLDS perform on the MTB wheels to insure consistency and durability?

PL: We subject our MTB wheels to thousands of hours of testing. Typically a wheel is tested for one full year in the lab prior to seeing the market place. While real world testing is important, the lab testing is literally a 24 hour, 7 days a week ongoing test-to-destruction process. We think we know what the wheels will do prior to ever seeing the real-world. For us, real world represents validation, as opposed to testing. The lab is testing. The real-world is validation. For approximately one year prior to putting wheels into the market place we set-up our manufacturing line, and we test the consistency of our process, the quality of our material (as an applied science), and the consistency of our hand-made work product. When product goes out the door to the consumer, the product they get typically is beginning (the) second year of production (year 3 or 4 since concept).

I think you ask a great question here, because when we speak of Reynolds quality I don’t know if your readers understand the engineering effort that goes into the product before they get it. What this means is that at Reynolds we do not follow new trends. We have to start a new product at a minimum of two years, and typically three years before the first day the product is available to the consumer in order to meet our strict internal guideline. Reynolds is significantly different in this way from companies that see a new trend, and put out a “me-too” product the next season. That is simply not enough time to design the product, set your supply chain, establish manufacturing protocol, and quality assurance, lab test, and finally validate (real-world test). So at Reynolds, rather than follow a trend, we try to create leading features and trends.

TNI: Seeing a respectable but not exceptional weight of 1620 g for the MT29er wheels it was not weight you went for most of all, right?

PL: Our MTB design is driven by strength and durability. Reynolds knows how to build super light weight wheels, for example our RZR road, and TT line. While weight is an important consideration, we determined that durability, and low weight/ reasonable weight is more important for an MTB wheel set than a fragile wheel set that challenges the market place for the light weight top- spot. What your readers should remember is, all wheel sets are not equally durable regardless of weight.

We prioritized durability, strength, and stiffness in this design. During the development of the 29″er we tested sets of wheels in the Cape Absa Epic in Africa, we had local pros hammer them into the ground, and we sent wheels to 24 hour races.

TNI: I understand that stiffness is a combination of rim stiffness and lacing (spoke count and tension, lacing, …). Reducing the number of spoke holes like with the MT29er (24 holes) further weakens the rim less when drilling them (and I assume your rims are drilled, not pre-laid with the nipple holes inside). What would be different with a 32 spoke count? Could the rim be lighter in this case?

PL: It is true that adding holes to a rim weakens it. It is not true that a pre-laid-up carbon rim with nipple holes inside is stronger than drilled holes. The strength of the rim/ wheel is determined by several factors. It is possible to drill holes in a rim and have the resultant strength equal-to or better- than a molded hole. If you test our drilled rims, you will find that they exceed the strength of the molded hole technology in the market place.

What is true is that more holes mean a weaker rim. In our testing we found that in MTB applications that it is more common for impact with trail hazards to result in bent or broken rims than in broken spokes. If you examine 1000 broken or damaged rims you will notice one thing they have in common. The break will either originate at a spoke hole (or valve hole) or propagate to a spoke hole (or valve hole). It is common sense that a stronger rim design has less holes. Based upon our testing, adding holes would not allow us to build a lighter rim. Because of the strength and stiffness of the rim, increasing the spoke count does not significantly increase our MTB wheel stiffness or strength. We also know that high spoke tension results in less maintenance, and wheels stay true longer with high spoke tension.

TNI: What is the motivation for the strongly inward leaning rim walls and the pronounced radius there? I assume it is tire bead locking (in junction with the rim´s inner raised shoulders), but also to eliminate pinch flatting. Is the also a engineering reason because it is carbon – I have never seen such a strong inward bend with alloy tubeless rims (That is until recently in the introduction of the new ENVE rims.

PL: This is a unique shape that we have developed and tested to enhance stiffness, strength, and durability which are the driving performance requirements. The inward leaning rim walls and radius help in several ways. As you have assumed with your question, yes, they help with bead locking, minimize pinch flatting, but they also structurally stiffen the rim.

Here’s how the shape stiffens the rim: It’s common knowledge that a tubular shape, “O” registers a higher torsion value than an open channel “C” shape. By leaning the rim walls inward we create a rim section that has the characteristics of a tubular “O” shape, as opposed to an open channel “C” shape. This enhances the torsion of the rim and wheel.

TNI: How much is the rim´s (and for that matter hub´s) individual weight anyway?

PL: Reynolds is focused on promoting their wheel system, and the rim is not designed as a stand- alone component.

TNI: Going for a 21 mm inner width, while most of your competition goes for 19 mm, looks like some serious abuse handling capacities, but the 24 h built looks a lot more XCish – What is the story there?

PL: We had some preconceived ideas when we started designing this wheel system, but starting with a clean sheet of paper, this was our best performing configuration. The extra width will give a better platform for tires from 2in up to 2.3in, and prevent them rolling as they would on a narrower rim.

TNI: Do you have a few words on the hubs – weight, ratcheting system, bearings, …. I could find nothing on them and I assume they are some high quality hubs as well :).

PL: Regarding weight, as with the rims, we are not focusing on hub weight, but rather overall wheel set weight. The hubs can be used with any axle standard. That means 9mm and 15mm bolt-thru for the front, and 135mm QR, 142mm/12mm and 135mm/12mm thru-axle on the rear hub. Ratchet is a floating 3-pawl system. The front hub has two 6804 RU (20x32x7) bearings with rubber seals on one side of the bearing. The rear hub has four 6902RS (15x28x7) bearings with rubber seals on both sides of the bearing.

TNI: In out intro we mentioned the REYNOLD´s ASSURANCE PROGRAM (short: RAP), which is a warranty to be purchased separately from the wheels for enhanced protection. Do you have a word on that for our readers?

PL: The Reynolds Assurance Program is a safety net for the consumer. With very few limitations Reynolds will replace a broken wheel or wheel component, no questions asked. This means
that Reynolds does not care if you crack your wheel on a rock or if it falls off of your car, and gets destroyed on the highway. We recognize the your wheels are an investment, so this is a very inexpensive insurance plan that has saved people thousands of dollars when something unexpected happens.

TNI: In our test set we have already switched end caps for accommodating different axle standards and find it super easy – the front wheels and rear non-drive side is simply done by pulling out the end caps and the rear drive-side by unscrewing carefully, which only takes a firm grip or possibly the assistance of a small wrench. All done without taking off the cassette or discs and within minutes. When wheels are purchased, are end caps or the means to convert the wheels included?

PL: All end-cap options/ components are included in every box. There is nothing extra to purchase to accommodate the preferred set-up. The consumer gets EVERYTHING the first time, so the purchase is completed in one transaction.

Thank you Paul for the time you took for this interview and information included and best wishes for 2012!!