Bontrager’s thrust into all things related to enduro is in step with its parent company's wholesale push into the popular genre with its bicycle development and racing program. The Rhythm Pro wheelset is the top model in the Super Enduro Series and its construction is based around a tubeless-ready carbon rim that is laid up with materials that are specially formulated for durability and impact resistance. The rim is plausibly wide, at 29 millimeters, with a 22.5-millimeter inside dimension and the low-profile rim flanges are molded with wide caps to ward off pinch flats.
Bontrager goes after the all-mountain/enduro market with wide, carbon rims, built into a lightweight and durable wheelset that is assembled in the US.
The rear hub features a quick-engagement freehub mech’ that provides a minimal 6.9-degree interval. The tool-less hubs use DT-Swiss straight-pull spokes and support quick release and through-axle applications as well as SRAM’s new XD 11-speed driver. Bontrager builds the Rhythm Pro TLR wheels in the US from components sourced in Asia. All three wheel diameters are available, with pairs ranging between 1610 to 1530 grams (claimed). Our 29-inch test wheels weighed 1600 grams. MSRP is set at $1075 for the front and $1125 USD for the rear in any diameter, and Bontrager offers a 30 day unconditional return and a two year limited warranty on its wheels.
Rhythm Pro freehub ratchets have three pawls with triple teeth. Construction
• Purpose: All-mountain/enduro
• Wide-profile carbon rim - 29mm outer/22.5mm inner widths
• TLR: tubeless ready rim design - molded plastic rim strip.
• 28 spokes, two-cross lacing, DT 14/15 gauge, aluminum nipples
• Rapid Drive - Fast engagement hub, 6.9-degree ratchet intervals
• Stacked Lacing hub design provides a better spoke bracing angle
• Offset spoke bed "OSB" rim profile further reduces wheel dish.
• Interchangeable axles and tool-free hub design fits quick-release and through-axle applications
• Compatibility: Six-bolt discs, Shimano/SRAM 10-spd or SRAM XD 11-spd
• Includes: Bontrager TLR rim strip, TLR valve, interchangeable axle parts
• Available in 26, 27.5 and 29-inch wheel diameters
• Actual weight, 29-inch size: Rear - 880g (12mm axle w/10speed freehub) front - 720g (15mm axle)
• Claimed weights (pairs)
: 26-inch - 1530g, 27.5-inch - 1585g, 29-inch - 1610g.
• MSRP: $1075 F, $1125 R
• Contact: Bontrager
Bontrager's designers went wild on the Rhythm Pro wheels, they are packed with features - some obvious and others hidden in the bowels of the hubs. Bontrager puts no weight limits on the wheels, so we assume that they are bomb-proof in all respects. OSB:
Offset Spoke Bed is Bontrager's term for the contemporary practice of shifting the centerline of the spoke holes to one side of the rim. Rhythm Pro rims are dramatically offset at the spoke beds to eliminate much of the 'dish' normally required to make room for the front brake rotor and in the rear, the cassette cogs. Stacked hub flanges:
The angle of the spokes is further balanced with the Bontrager hub's stacked spoke flanges. The rear drive-side, and front braking-side hub flanges are machined with radial segments - each drilled for two straight-pull spokes. The holes are stacked one above the other, so both spokes radiate to the rim from the widest possible angle.
The Rhythm Pro front hub (left) shows the unique straight-pull spoke lacing arrangement. The inset view of the rear hub's drive-side flange reveals the double-drilled 'Stacked' spoke lacing, used to optimize the angle that the spokes enter the rim.
The freehub ratchet employs three pawls, each with three teeth. There are 52 clicks on the engagement ring, which result in a minimal 6.9-degree lag interval. The average is around 12 degrees. Beefy pawls and the triple tooth feature suggest that the ratchet mechanism will hold up well. Tool-less construction:
The freehub mechanism, axles and endcaps can be pulled apart by hand for inspection or service. We switched out our rear hub to a SRAM XD driver and axle assembly (available from Bontrager)
in less than ten minutes. An endcap kit is included with purchase that supports 15QR and 12mm through axles as well as standard quick-release types.
Bontrager's TLR tubeless system (left) employs a rigid plastic rim strip to capture and seal the tire. Offset spoke holes provide more equalized spoke angles and tension. The red line is the center of the wheel. the gray line to the right is where a conventional drive-side spoke would be positioned.
Bontrager's TLR tubeless system uses a stiff, molded plastic rim strip that snaps tightly into the rim well. The fit is so close that it is hard to discern where the edges of the strip end and the beads of the rim flanges begin. A raised section elevates the valve stem above the tire beads to facilitate mounting. The rim strip can be used with a tube, but the valve stem must be long enough to compensate for the extra six millimeters of plastic there. The sum of the rim strips and brass valves adds 100 grams to the wheels. Wide rim profile:
Wider rims are possible in carbon without the weight penalty associated with aluminum. Rhythm Pro rims nearly reach the emerging 30 millimeter standard for XC/trail, with a 29-millimeter outer and 22.5 inner measurement. That, and the rim's low-as possible flange height add stability to the tire for cornering and heavy braking, and provide an improvement in rolling resistance.
A look at the raised area near the valve stem of the TLR rim strip and the wide caps of the Rhythm Pro's rim flanges. A molded boss ensures that the valve stem will be well supported and compensates for the dramatic offset of the rim's spoke bed.
We mounted the Bontrager Rhythm Pro wheels to their 2.3-inch SE4 tires for testing and for a control, we also mounted up a Schwalbe Rocket Ron 2.35-inch tubeless ready tire. Both were a tight fit to get over the rim, presumably because of the additional thickness of the rim strip. Unlike the fussy tubeless ready rim strips that DT Swiss are infamous for, the Bontrager versions do not fold under or distort when using tire levers to get the rubber mounted to the rim. Once the wrestling match was won, the tires were inflated with a floor pump and snapped into place at 45 psi (3 BAR)
. Removable valve cores allow the sealant to be injected after the tires are successfully mounted. We switched the freehub from ten speed Shimano to 11-speed SRAM. Bontrager sent us the optional kit, which included a drive-side endcap, a new axle and the HD freehub driver. We simply pulled apart the hub (the non-driveside cap required help from a pair of pliers)
, slid the new parts into place and pushed the endcaps back on. Like DT Swiss hubs, the endcaps secure the assembly with internal O-rings that grip the axles.
On the trail, the wheels feel quite rigid in the lateral plane, with a sharp feel under hard acceleration out of the saddle. The stiffness translates to more secure steering in the boulders which are abundant in our test trails. The freehub ratchet engages almost instantly, and thankfully, it does not announce the fact that it has 52 engagement points to the world with an obnoxious hiss or growl. The Rapid Engagement feature emits a subdued noise while coasting, which is helpful when passing or approaching non-cyclists.
With plenty of rocks to bottom out the tires, we had ample opportunity to crack the rim flanges. Happily, the Rhythm Pro rims are intact and running true. The maker installed enough decals on the raw carbon surface to form an anti-scratch barrier, but we did manage to inflict a few gouges into the carbon that have not amounted to anything more than cosmetic flaws in otherwise fresh looking wheels. Carbon rims hold their shape and do not bend when stressed, unlike aluminum types. so they tend to remain true and tensioned far longer. The Bontragers supported this theory and have not required a spoke wrench for over two months of winter testing on all-mountain style trails. So far, the Rhythm Pro wheelset has put in an excellent performance. Issues:
We found few downside issues to report. Owners should beta test the length of the valve stems in their spare tubes, because the addition of the raised section of the rim strip and the extra thickness of a carbon rim eat up abut ten millimeters of stem length. The only other question that arose was purely cosmetic - the machined finish of the Rhythm Pro hubs seemed a bit cheap for such an otherwise polished looking wheelset.Pinkbike's Take:
|Snobbery might be the only reason for top bike-handlers to pass up Bontrager's Super Enduro Carbon wheelset. Rhythm Pro TLR wheels are well designed and supported by a solid warranty - and at just over two thousand bucks, represent a good value for an elite level carbon all-mountain wheelset. The performance is there too - with demonstrated stiffness, a sweet engagement feel and excellent durability. Can they be broken? Every wheel can be broken, but the fact that Rhythm Pro carbon wheels come without rider-weight restrictions should be a hint that Bontrager erred on the strong side when they chose their carbon layup schedules. We are sure that some riders will pass on Rhythm Pro wheels simply because they are a Trek product. Those who can look past the label, though, will see a pro-level wheel in every respect, sold at an attainable MSRP. Put Rhythm Pro TLR wheels on your shopping list. - RC |