ENVE Twenty7.5 (650B) AM Review

by Brian Mullin on July 7, 2012

At Sea Otter this year, ENVE introduced a 650B rim, which they are
calling the Twenty7.5 (650B), and they’ll come in an AM and XC version.
The Twenty7.5 rims are 31mm wide (24mm internal) and weigh in at 410
grams for the AM, and 24mm wide (18mm Internal) and 360 grams for the
XC, and will retail for an $875 each. They will also be available as
built wheelsets, using the DT 240, DT 180 and Chris King ISO hubs. Like
all their rims, the clinchers use 100% uni-direction carbon fiber
construction, and use their molded spoke hole technology, and are hand
built in their Utah plant.

I like the 650B size the longer I
use it, and it’s an interesting product, with attributes and
characteristics of 26″ and 29″ wheels, and sometimes right in the middle
of the pack. The actual bead seat diameters for the 26, 650B and 29
wheels, are 559, 584 and 622mm, respectively, so it’s closer to the 26″
size. I picked a few outstanding conditions and terrain that are
encountered while riding and how I thought the 650B wheel size matched
up against its brethren:

  • Slow climbs – 29 like
  • Fire roads – 29 like
  • Fast singletrack – 29 like
  • Downhill – middle
  • Rough climbing – 29 like
  • Up switchbacks – middle
  • Down switchbacks – 29 like
  • Technical – 26 like
  • Maneuvering – middle


ENVE Twenty7.5 AM
This is going to be a different review, since although I am testing a
wheelset; I am primarily focusing on the ENVE rims themselves. The
wheelset I tested are comprised of the ENVE Twenty7.5 AM carbon rims (32
hole), laced to Chris King ISO hubs (15mm front and 12x142mm rear)
using DT Swiss Aerolite spokes, and they retail for $2550. The basic
dimensions of the rims are an outer width of 31mm and an inner of 25mm,
and a height of 30mm, and they are available in 28 and 32 hole
configurations. The prebuilt wheels weighed in at 1701 grams, and I’ll
have to use their specs of 410 grams for rim weight, since I was unable
to measure them myself. For an All Mountain rim, weighing in at 410
grams is pretty amazing, and the big chunk of weight for the wheels was
the moderately heavy Chris King hubs. For a lighter build, using DT
Swiss 240 or 180 hubs can drop 110g and 180g respectively from their
heft. You can purchase the rims separately for $875 for your own custom
build. The rims have a 5-year defect warranty for materials and
workmanship, and a Lifetime Crash Replacement policy, in which the
replacement would be 50% off MSRP.



ENVE Technology
The ENVE rims are handmade at their facility in Utah, and the rims have
gone through extensive and rigorous torture, including lateral
stiffness and spoke testing, and meet the strenuous UCI test protocol.
They have a molding process for the spoke and valve holes, so that the
carbon fibers are continuous and unbroken around the holes, which
creates maximum strength and allows increased spoke hole tensions. In
addition, they mold in a conical nipple seat, which reduces spoke
breakage and allows nipple articulation.  In another innovative design,
they use removable bladders, leaving no excess internal material, so
they have a lighter end product and one that make for easier wheel
builds. The unidirectional carbon rims are unpainted, without any
coating or finish, and are raw and naked, other than a few decals.

Testing Rig and Terrain
Testing was performed on my medium Ibis Mojo HD with the Cane Creek
Double Barrel Air rear shock, Magura TS8 27.5 fork, and Schwalbe Nobby
Nic tires. I am 5’9″, weigh in at 155 lbs and have been riding since the
inception of the RockShox RS-1, and started out on a Bridgestone MB-2
for my first MTB steed. I have mostly ridden in the West, including vast
portions of the Colorado Front Range, Sedona, Moab, Fruita/GJ and many
parts of the Colorado mountains. The testing terrain is predominantly
loose rocky conditions, with many long steep climbs and descents, rock
gardens, slick rock, an occasional smooth singletrack and lots of ugly
loose gravel.

Impressions
I got to test the ENVE wheelset for four weeks, so it was a pretty
quick review period, but it didn’t take long to love the attributes of
their carbon rims. The rims have excellent damping characteristics,
without feeling deadened or overly stiff. The rims are quite light at
410 grams for an All Mountain beast and they accelerated and rolled
quickly, and their low rotational weight is very noticeable, especially
when spinning, steering and cornering. When the wheels were rolled up to
speed they felt like they had a little motor in them, and they spun
like a buzz saw, greatly helped by the smooth Chris King hubs. They
really came to life when I was sending the wheels through curvy terrain
with lots of berms and rollers, and you could plow them in and out like
crazy, making for a hooting and hollering session as you pounced on the
terrain. Tossing them into a pump track was pure ecstasy, and brought an
instant grin to the face. When pressed into corners and steered hard
through difficult terrain, you could feel the exceptional lateral and
torsional stiffness, which corresponds to excellent control and
precision. The less tangible thing about these rims is that they feel
nice and comfy, and offer a superlative ride quality. They have
stiffness in all the required directions, yet they provide a touch of
resiliency, damping and softness.

I ran them with a set of the
sweet new Schwalbe Nobby Nic 650B tires, which are 2.34″ wide, and
together they came in at a whopping 27 13/16″ tall. The wheels came with
their tubeless tape installed, which looked a bit like fancy duct tape,
so I just installed the extra tall valve stems, which are required due
to the extremely tall 30mm rim height. I ran them with tubes for a week,
but the Nobby Nic really came to life in a tubeless mode, so I left
them that way for the rest of the test period. Their tubeless tape has a
rough surface, so taking tires on and off, and using tubes seems to
abrade them and wear things away, so I had to add a layer of tape to
seal an errant air leak when trying to go tubeless on one rim? One
annoying thing is that the rim bead hook likes to hold onto the tire’s
bead, and it can be an ugly wrestling match to get them to separate. I
cursed more than a few times trying to get them to part ways, and it
didn’t seem to matter how long the tire had been on the rim, and it was
like they were sucked up into the void and glued on?

The rims were
stiff and strong, and offered incredible steering response and control,
and concerning capabilities. In the rear, they added an extra bit of
punch to the traction and control since you could really apply torque to
the wheel with immediate power and got instant feedback, which was
greatly helped by the high POE of the Chris King hubs. Due to the
stiffness of the rim and the inherent ability to apply so much torque, I
could feel the spokes and drivetrain ping a bit under power, which was
exacerbated by my personal usage of low gearing. Although not all riders
might have this issue, I would prefer beefier spokes in the rear for
additional strength and less noise. The rims are brutally tough and
bashing and smashing them through my typical heinous gravel fields,
rocks gardens, slabs, ledges and other sundry rim destroyers did nothing
to the sidewalls and rim edge, other than a peeled decal or two. I was
pretty amazed at the strength and durability of the rims, and I would
have assumed they would show some sign of wear and tear, especially with
the unforgiving terrain that I tossed them into, but they were none the
worse?

The rims are brutally expensive at $875 each, but their
toughness, durability, stiffness and strength mean they will outlast
most wheelsets, and that longevity should greatly increase the
cost-benefit ratio? You can build a lighter wheelset with different hubs
other than the Chris Kings, but their hubs are well-made and durable,
and they needed no maintenance, other than an occasional tightening of
the preload adjuster. The ISO hubs are easy to take apart, even in the
rear, and their replacement axles and adapters are simple to install for
any wheel configuration. They do make a pretty wild buzz and zinging
noise, especially when they are wound up to speed.
Measured Specs:

  • Rear Weight w/ Chris King ISO 12×142 & tubeless tape – 907.2 grams
  • Front Weight w/ Chris King ISO 15mm & tubeless tape – 793.4 grams
  • Wheelset Weight  – 1700.6 grams
  • Rim Dimensions – Inner 24.5mm, Outer 31.2mm, Height 30.2mm

Bottom Line
The ENVE Twenty7.5 (650B) AM rims are light, and have exceptional
lateral and torsional stiffness, yet they offer superlative ride
quality, with excellent damping and comfort qualities. Their low
rotational weight makes them highly functional (and fun) while cornering
and spinning, and their stiffness offers control, precision and power transition. The
well-built and innovative design is extremely tough and durable, and
should offer excellent long term usage, which is a good thing, since
they’re brutally expensive at $875 each.

Strengths

  • Lightweight
  • Exceptional lateral and torsional stiffness
  • Superlative ride quality
  • Extremely tough and durable

Weaknesses

  • Brutally expensive
  • Tough to separate installed tire from rim bead hook
  • Tubeless kit is optional

Overall Rating: 5 Flamin’ Chili Peppers

Twenty7.5 (650b) AM Specs:

  • MSRP : $875
  • Depth – 31mm
  • Width – 30mm (24mm Internal)
  • Rim weight – 410 grams
  • Wheel weight – DT 240 1378 grams, DT 180 1406 grams. King ISO 1588 grams
  • Hole count – 28 or 32
  • ERD – 556
  • Finish – UNI

Twenty7.5 (650b) XC Specs:

  • MSRP : $875
  • Width – 24mm (18mm Internal)
  • Rim weight – 360 grams
  • Wheel weight – DT 240 1478 grams, DT 180 1306 grams, King ISO 1488 grams
  • Hole count – 28 or 32
  • ERD – 556
  • Finish – UNI

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