Mountain biking and the triple-chainring crankset are conjoined twins in the minds of most, which has proved to be a greater stumbling block for the proponents of 2 x 10 than was anticipated. SRAM
poured untold marketing money into its XX two-by-ten campaign. The sport’s most influential riders and a groundswell of rank-and-file enthusiasts have long-abandoned three chainrings in favor of a more simple single or double arrangement. The validity and versatility of one-by and two-by drivetrains has been proven world wide, from Whistler to the XC World Cups—and yet there still is a great reluctance within the sport to embrace the less-is more philosophy. The pushback is based upon two fears: first, that small chainrings just look wrong; and second, that two-by or one-by gearing range is too limited, so one must give up top speed, or give up low climbing gears to subscribe.
Why nine-teeth matter: The gearing spread on the left represents an old-school triple crankset (22,32,44) driving an 11 x 34 cassette. The far right is a double crankset with small, 24/36 chainrings, powering a 9 x 36 cassette. The graph shows that the nine-tooth gives the two-by-ten almost an identical climbing gear and the same top gear. Compare this to Shimano's 3 x 10 second from left. -Race Face graphic
Recent developments to adapt wide-range gearing, spearheaded by Hope and Specialized, promise to address the only substantial drawbacks to single and dual-ring drivetrains. The most significant being Hope’s innovative cassette based upon a nine-tooth cassette cog, while Specialized, has taken the leadership role in applying 2 x 10, 1 x 10, and nine-tooth to its trail, all-mountain and downhill designs. Pinkbike interviewed Hope’s Neil Arnold and Specialized’s Brandon Sloane to get the facts about the new 9 x 36 cassette, and how it may affect MTB drivetrains in the near future.
Pinkbike Interview: Hope’s Neil Arnold and the 9 x 36 cassette
The nine-tooth cog is roughly the same diameter as the spline of a standard freehub. To prevent premature wear, Hope machines the last five cogs in one piece from a steel alloy which will remain a secret.
Hope Technologies introduced a 10-speed cassette, based upon an impossibly small, nine-tooth cog last year that may erase all valid reasons to choose an old-school triple crankset. Hope’s ultra-wide-range cassette was intended from the outset to give single and double-chainring users a versatile gearing spread comparable to Shimano’s contemporary triple-crankset options.
The Hope cassette is revolutionary because the freehub pawls and bearings are integrated into the cassette, which eliminates the conventional spline-and-lock-ring arrangement of a standard hub. The Hope cassette slides onto the axle and plugs directly into the hub’s ratchet ring. The cogs are made in two blocks, the five larger sprockets are machined from aluminum, while the nine-tooth cog and its four brothers are machined from a single piece of alloy steel. Hope’s simple design eliminates a few complicated parts and allows the smallest cogs to overlap the larger-diameter cassette bearings and sprocket carrier housing. We asked Hope's Neil Arnold to give us the inside story on how the 9 x 36 project came to be, and who might want to use one.
Neil Arnold explains the reasoning behind Hope’s simpler-is-better approach to drivetrain technology:
The key element of the Hope cassette is that the freehub engagement pawls are machined into the cassette body. Sealed bearings in the cassette run directly on the rear axle - elegantly simple
PB Is there one person you attribute the development of Hope’s 9 x 36 cassette to?
Not one person, but the ‘brains’ behind it at our end is Simon, one of the co-owners and designers and Owen, the chief designer. The idea or concept could be credited to all those who ride though, and who inspired something of this type. PB We have been warned that nine-tooth sprockets wear quickly. What material does Hope use for the block of five small sprockets?
At the moment that’s a secret I’m afraid! We don’t have many – but that will have to be one of them. We originally experimented with aluminum on both the upper and lower sets of sprockets, different types, different coatings… then some steel, we’re still developing it though, so no final decisions as yet – suffice to say that we won’t release something that isn’t ready and we’re not totally happy with as far as longevity, wear and performance goes. PB What motivated Hope to develop the nine-tooth cassette? Downhill? Trail?
Cross-country/trail, first of all. A few of us have experimented with single rings, single-speed, 2x9 set ups, 1x9 set ups – and the type of riders and the kind of riding that we do allows us to run these setups. It’s not for everyone, that’s an important factor to realize. It suits some people and their riding, although more could benefit from it if they ‘adapted’ slightly. The DH side of things has started to come into play already though, even in the development stages. We’re playing about with six-speed set ups with close-ratio ranges to work on smaller front rings – something all DH riders and bikes could benefit from. PB The inside diameter of a nine-tooth cog is too small to fit a standard cassette. What modifications did Hope devise to circumvent this problem?
We’ve always followed the ‘industry standards’ as far as components go. We make aftermarket upgrade parts, so we fit and work with what exists. As we already make the freehub body for the hub, it was an ideal part to work with to do what we wanted, and not what already was out there. We therefore combine the freehub body and cassette into one piece, allowing the lockring to be removed and therefore the smaller sprocket sizes to be achieved. It’s a real ‘why didn't anyone do that before moment’ when you look at it! PB Hope's 9 X 10 system reportedly only interfaces with special Hope hubs. How does the Hope freehub differ from standard?
What is standard? Our freehub body fits our hubs, of course. The new cassette fits on all our current Pro 3 and Pro 2 Evo hubs, and will retrofit back onto the Pro 2, when an axle and spacer kit is used to convert it. PB How does Hope believe this development will change the future mountain bike?
Simpler, lighter, less complicated - all the things we all want our bikes to be!
Hope's 9 x 36 cassette paired with a 24/36 double crankset produces a wider range of gear selections than a Shimano XT triple with a 11 x 36 cassette
Pinkbike Interview: Brandon Sloane and Specialized’s one-by and two-by drivetrain development.
Chain guides for XC: Specialized's Epic Expert Evo 29er comes stock with a single, 34-tooth chainring and a guide--a new look for skinny-tire production bikes.
When Specialized mobilizes most of its MTB group to develop a drivetrain concept, it indicates that big changes are in the wind. Specialized’s design team was an early adopter of the nine-tooth concept, and had already committed much of its 2010 all-mountain and trailbike range to single- and two-ring drivetrains. Specialized’s pro DH team was secretly using custom, nine-tooth cassettes on the World Cup circuit (link to PB story) and was testing Enduro and Stumpjumper prototypes with 9 x 36 cassettes crafted from Shimano’s little-known Capreo compact road-bike components (link to PB art) grafted onto Deore XT cogs. Specialized is pushing two-by and one-by drivetrain development beyond of-the-shelf options from SRAM and Shimano at a time when notable bike makers are still arguing the merits of triple-chainring cranksets. Pinkbike asked Brandon Sloane to walk us through Specialized's drivetrain philosophy.
Brandon Sloane on the direction Specialized's new drivetrains are taking its trail, AM and DH designs. PB How does 2 X 10 fit into Specialized's trailbike and AM lineup?
SRAM and Specialized co-developed lightweight guide rings that keep the chain from overshooting the big sprocket on Specialized's two-by-ten trailbikes
We went big with 2x setups for almost all trail (SJ FSR) and AM (Enduro) bikes. Enduros have actually been double for some time now (before 10sp). All of our categories have a specific 2x setup tuned for experience and wheel size. Epics and Hardtail's get bigger gears than Enduro bikes and 29-inch wheels get smaller gears than 26-inch wheels. We tend to err of the side of low gearing. We like to make sure you can get up the hills. I think many stock 2x10 offerings (XX and XTR) are too big for Trail and AM use and even XC with 29" wheels. Other brands tend to run bigger gears (because that is what SRAM/Shimano offer up), but we focus on climbing rather than pedaling a 42x11 on the road down a hill. PB Is it true that Specialized and SRAM are working closely on new drivetrain developments?
SRAM was a great partner with our 2x10 setup making custom ring configurations (24/38 for Stumpjumper FSR) and other setups (like the carbon and alloy shift guards. These are not for bashing - just a little something (that is very light!) to help keep your chain on. PB You've been on single and dual-chainring bikes forever. What would be your gearing choice for trail riding?
On my trail bike (SJ FSR 26") I run a 24/36 in most cases up front with 11/36 cassette in the rear. On my Enduro, I have a 1x10 setup with a 31-tooth up front and custom 9/36 cassette in the rear. Of course, a shift guide on the double and light single-guide on the single. Unfortunately, chains still fall off without them!
PB Grassroots 2-by and 1-by riders have all adopted some sort of chain retention system, and Specialized is using roller guides on some XC and AM models as well as outer guide rings on 2-by traibikes. Shimano and SRAM, however, have yet to address the subject. A couple of thoughts on the subject?
Brandon Sloane is riding the same prototype 9 x 36 cassette that Pinkbike photographed on Curtis Keen's Enduro FSR. The first four cogs are patched from a tightly spaced road cassette, which makes for less-than optimum gear ratios--this will be addressed for future production.
Yes. We are all for guides, but there are plenty of opportunities to make them better. Today's systems are mostly overbuilt based off of DH systems. We keep weight in mind on most Stumpjumper FSR's (with outer shift guard only) and a light Gamut system on Enduro and Stumpjumper FSR EVO. We made our own super light XC guide for Epics this year and will continue to make our own systems or have them made (like the Gamut shift guide) in the future. SRAM and Shimano are aware of the problem so I am sure you will see something from them.
PB Specialized moved the DH tech needle with Sam Hill's nine-tooth cassette and now Pink Bike has ridden a nine-tooth prototype cassette on Curtis Keen's Stumpjumper EVO trailbike. Specifically, what were the advantages Specialized was looking for in each case?
Specialized teamed up With Gamut to produce a lightweight roller guide for the 2 x 10 Stumpjumper FSR
Nine-tooth for DH came about from trying to help Sam and Brendan from smashing their chain guides during racing/practice. With the low bottom bracket of the Demo, a guide with a 36-tooth ring gets pretty beat up. The nine-tooth in the rear allows us to run a smaller front ring and guide, lessening contact. There are also a few other benefits when you setup the nine-tooth with the number of gears the guys are actually racing on. You will see other improvements based around the nine-tooth soon! Nine-tooth for Trail will be a little more difficult, but we are pushing for it. To take advantage of the wide range nine-tooth could give you, your chainring size options will need to change a bit (for singles). Also, the 9/36 cassette creates pretty big steps in the gear changes, but all these things can be solved for.
Sam Hill's radical six-speed cassette was the debut of nine-tooth in DH.
Contact Specialized and Hope to follow the proression of wide-range nine-tooth cassettes and drivetrains.To earn your Pinkbike doctorate in drivetrain development, please submit a brief dissertation on the nine-tooth concept.
The reason for Hill's nine-tooth cassette was to use a smaller, 30-tooth chainring without affecting Hill's overall gear ratios--a ploy by Specialized to raise the chain guide out of harm's way.