Bike: ‘Plus-3’ 29er Demo Bike
Riders: Mike Ahrens/Mike Shulko
Location: Saratoga Gap Open Space Preserve
Duration: 2.0 hours
Today was my first real dirt ride on the new ‘Plus 3’ 29er aluminum frame I developed for the Handmade Bicycle Show a few weeks ago. I wanted to ride yesterday but was too hung-over from St. Patrick’s Day festivities the evening before….when else can a 6’4” red-haired Irishman really let loose? :-)
Needless to say the weather was excellent, sunny but brisk with slightly damp trails from previous rains. The ride started out with a descent into tight rolling and slightly rocky singletrack which runs parallel to Skyline Blvd…superbikes screaming by my left side every minute or so. I've ridden this trails many times and the 29er immediately felt at home with predictable handling and cornering – overall providing a very neutral feeling in the cockpit. Once I got a little warmed up, the challenge became pedaling the larger diameter wheels since they seem to require a little bit more effort during the many short uphill transitions this trail offers. I could also have been ‘getting the lead out’ of my legs which haven’t been used for cycling in quite some time due to fatherhood!
Brief Background: The frame plans were dropped off at El Camino Fab in Oakland in mid-February and Jason Grove did an excellent job completing the frame in a short amount of time. The frame is built from Easton 7005 tubing throughout; the down tube I chose was straight gage (1.8mm wall) with no internal butting. Rear triangle tubing is rectangular with the seatstays being slightly narrower than the chainstays for weight savings. CNC machined dropouts and yokes round out the package to provide excellent tire clearance and very simple construction methodology. Frame weight is 4.18lbs raw – not bad for a 19” frame size!
I researched a wide variety of technical information on 29ers before settling on this frame's geometry. I tweaked a few dimensions from my standard ‘APEX’ hardtail design to accommodate the larger diameter wheels. In general, the head angle was increased (aka ‘steepened’) by one degree to 71 deg to maintain proper trail and predictable handling characteristics when mated to a 100mm travel fork. The chainstays were lengthened by ~½” to enable good tire clearance and room for the front derailleur to travel down to the small ring. The remainder of my tried-and-true hardtail frame geometry stayed intact including a moderate 24” effective top tube length, 72 deg seat angle and 19.25” seat tube length (center to center). With larger wheels and taller XC suspension fork, the head tube's position ends up high and definitely caters to taller riders. As a result, the top tube slopes very aggressively downward toward the seat tube to provide excellent standover clearance.
Parts Overview: The Maverick SC32 single-crown inverted fork is mated to a Maverick 24mm bolt-thru hub, 32 hole and 3X laced with Sapim spokes to a Velocity VXC disc rim. Rear wheel is a Hugi 240 disc hub, 32 hole and 3X laced with Sapim spokes to an identical Velocity VXC rim. The Velocity VXC disc rims have a nice 23.5mm width and low overall weight...my goal was to keep the wheels as light as possible to minimize rolling resistance. The rest of the bike is a mixture of FSA high-end parts (carbon cranks, carbon 31.8mm bars, headset, K-force stem and K-force saddle), XT 9-speed drivetrain, Hope Mini brakes (185mm rotor front/165mm rotor rear) and WTB Mutano Raptor 2.30” high air-volume tires.
Back to the ride….after the first sliver of singletrack was done, Shulko and I dropped down onto another piece of singletrack that is normally ridden uphill only – multiple trail closures made our choice to ride this trail pretty easy since it was the only one open. This trail was similar to the first trail except a little wider and then it opened up into a small plateau with manzanita brush encroaching both sides of the trail. Placement of ‘speed logs’ every fifty or sixty feet forced us to keep speed down for the most part (bummer!). The 29er floated over most of the lateral logs with ease once I got used to the tires’ ability to roll over almost anything. On taller logs, the slack seat angle and relatively short chainstays enabled me to wheelie over these obstacles confidently. Since the head tube position is slightly taller than normal, pulling up became even easier – maybe even too easy but I need more time in the saddle to figure this out. Overall I felt secure tackling the most basic trail obstacles since the larger diameter tires seem to maintain their momentum once I got up to cruising speed. This trail dropped us off onto a very wide fire road that we eventually climbed up (2.7 miles!) to get back to the car.
Climbing up the fire road was definitely a chore due to mud bogging and my being out of shape. I must mention that mud clearance on this bike is tight between the back of the seat tube, front derailleur cage and 2.30” rear tire but in this case the mud wasn’t thick enough to cause major issues. I plan on swapping out the rear tire with a WTB ExiWolf 2.10” to gain some needed space…and I will be researching e-type front derailleurs to see if they will be beneficial to increase clearance. Since 29ers are here to stay, I believe there is a market for low-profile, high-clamp front derailleurs that will work on this application. The front-end geometry worked out well for climbing – my only gripe is that the handlebars were setup too tall and the front end would wander when the fork was at full-extension during steeper climbs. By ‘locking down’ the fork with the flip of a lever, I was able to steepen the head angle and climbing became much simpler. I will be removing some spacers from under the stem to tweak my climbing position even lower before my next ride. And the 12-34 XT cassette’s gearing was a nice match to the larger diameter tires.
Summary: I am very pleased with my first dirt ride on the 29er….when compared to some steel 29ers I’ve ridden in the past, this bike clearly out-handled them and exceeded my expectations with its nimble character. By keeping the head angle at 71 deg, I am certain that anything steeper is too steep for 100mm travel forks for this application. The Maverick SC32 is a nice compliment to this bike since it has excellent lateral rigidity and tuning adjustments take only a minute or two. The ½” longer chainstays did not adversely affect handling as I expected they would….in fact I now believe they are a logical match to the larger diameter wheels. On 26” bikes it’s desirable to keep the chainstay length very short to improve responsiveness – in the 29” world this fact isn’t supported because the tires' contact patch is increased to provide more noticeable traction. This bike carves corners, climbs well during transitions, is easy to maneuver at slow speeds and wheelies over logs and rocks predictably…..overall a well-rounded package that inspires rider confidence!
Bike: ‘Plus-3’ 29er Demo Bike
Posted by Mike Ahrens at 12:32 PM