I thought I'd share this message recently posted in another news group
regarding the Batavus Ouverture, a euro style bike imported from the
Netherlands with the NuVinci CVP Transmission. Both the NuVinci Wheel
and Batavus Ouverture are available at Edina Bike & Sport.

Carl
Edina Bike
952-929-0313
www.edinabike.com (over 25,000 items)

It is a simply brilliant commuter bike with dual roller brakes,
dynohub, fenders, full chain case. It aint light, and it aint
cheap, but it's a low-maintenance stylee ride for the non-racey
commuter with some cash flow.

The following is a review of the NuVinci hub by a colleague. While
it is true that the company Val works for is the US importer of the
bike I ... trust their opinion more than anybody else's in the
industry except for the world-famous (in bike circles) Sheldon Brown.

The Batavus Ouverture is one of the best overall solutions if you
want a heavier, but super-reliable, euro style commuter bike.



The NuVinci CVT Bicycle Hub

A Review

Since before the turn of the twentieth century, the development of
gearing systems for bicycles has inspired a vast amount of technical
invention and innovation. The overwhelming variety of drive train styles
has been the subject of many articles and several books, and new
developments continue to appear. One goal that has obsessed inventors
almost from the beginning has been the creation of a continuously
variable drive system. There have been many attempts to build such a
system, which would allow the rider to change the gear ratio throughout
the range without being limited to specific gear increments. Until now,
all the imaginative approaches to this mechanical conundrum have been
either completely unworkable, or inappropriate for use on bicycles.

The NuVinci Continuously Variable Transmission hub has finally achieved
this goal: a bicycle drive train of moderate weight, good efficiency and
durability under torque, with an infinitely adjustable gear ratio and a
range of 350%. As one of the first US distributors of this revolutionary
hub, Seattle Bike Supply recently received a sample, which we promptly
built into a wheel, installed on a bike, and began testing under the
toughest conditions we could impose. I had the privilege of riding it
for the first week, and these are my impressions.

The hub itself is larger and heavier than any other internally geared
hub, but not unreasonably so. The 150 mm flange means that wheels must
built in a two cross pattern, and the resulting wheel will shift the
center of gravity rearward on the bike. Initial installation requires
careful attention to the instructions, as the shifting mechanism must be
properly installed on the axle, but once the set up process is complete,
removing and reinstalling the wheel is only slightly more complex than
it would be for a standard bolt on wheel, and easier than a coaster
brake wheel (our wheel was set up for disc brake use - there is also the
option of using the Shimano roller brake, which would make removal and
reinstallation more difficult). The shifter uses a double cable system,
and is easy to install when assembled with cables and axle mounted shift
box. Setting up the cables and shift box is a somewhat complex process,
but not too technically sophisticated. The twist grip style shifter
makes one full revolution going from the low end of the range to the
high end, and has an unusual display which indicates the ratio without
numbers. In the lowest ratio, a red line forms an inchworm-like hump,
indicating the sort of hill you can climb in that ratio, and as you
shift up, the line flattens out, until it is perfectly straight for the
highest ratio.

Once we had a working bike, I began using it as my primary commuting
bike. My daily commute is 8 miles one way, and the return trip involves
1 ¼ miles of 9.6% uphill grade. To make things more fun, it is winter in
the Pacific Northwest, and rain, grit, mud and freezing temperatures add
to the conditions that any bicycle must endure. I am also the sort of
person who always needs to have a certain amount of paraphernalia (tool
kit, thermos, lunch, rain gear, first aid kit, etc.) and cargo space for
running errands. I never travel light, so I was towing a two wheel cargo
trailer at all times during this week of testing, with a minimum of 20
lbs. on the trailer.

During the first day of riding, I did have some minor problems with the
axle slipping in the dropouts, but this was easily rectified with more
torque on the axle nuts. Once the wheel was properly secured, I was
unable to cause any sort of malfunction whatsoever, and I did try.

The function of this hub is different than anything you have ever
ridden. There are no "gears" as we know them. The range built into the
hub is the equivalent of having an 11-38 tooth cassette, but the rider
does not select a gear within this range. Instead, you simply adjust the
ratio to match your riding preference and the terrain. It feels like
turning a dimmer switch or the volume dial on your stereo. The hub is
always "in gear" because the mechanism is always engaged, and always
capable of transmitting the pedaling torque to the rim. Because of this,
there is no way to miss a shift, and no need to worry about when you
should shift. You can always shift, whether pedaling, coasting or stopped.

One of the best aspects of this is that it makes shifting simple. It is
no longer something you need to think about at all; if you want to
shift, you shift, any time, even when stopped. Even so, using the hub to
its best advantage does involve learning some different habits. During
the first day of riding, I found myself waiting until my cadence was
high enough to get into the next gear, a good habit with any other
gearing system, but totally unnecessary with the NuVinci. When
accelerating, it is possible to shift continuously, keeping your cadence
constant as you go from a stop up to cruising speed. If you shift a
little too far, and find yourself in a ratio that is a bit too high,
adjust back down a little - there is no trauma, no hesitation, no chain
slipping.

Once I got used to shifting whenever I felt like it, I found that the
hub gave me some very useful feedback about my pedaling stroke. The
manufacturer states that you can shift the hub under load, and while
this is true, it is also true that any system under load will resist
shifting. The more force you are putting on the chain, the more force it
will require to move the shifter. If you have consciously developed the
habit of relieving the pressure on the pedals when your hand shifts,
this will be no problem, but if you do shift this hub under pressure,
you will find that it tells you exactly where the "dead spot" is in your
pedaling stroke. Under rapid acceleration, with moderate pressure on the
shifter, the hub shifts in small increments every time your foot hits
that spot. I found that in some circumstances, I actually had almost no
dead spots in my stroke, and at other cadences, on different terrain, I
seemed to have three. Very educational; after a while the feedback
between feet and shifting hand becomes totally instinctive, with no
intervention from the brain at all.

The ease of adjusting the ratio also led me to discover an interesting
riding strategy - I found that when my legs were laboring on long
upgrades, I was able to shift down just slightly and spin a bit faster,
sometimes just for two or three pedal strokes, and then shift back up
into the original ratio without any trouble. With a conventional gearing
system, the need must be dire before this sort of multiple shift is
worth the trouble.

I did try to put as much torque on the hub as I could, to see if I could
break anything, with no success. After one grocery run, I chose the
steeper of two possible routes home to haul the 60 lbs of trailer and
supplies home, but even muscling over speed bumps on an extreme slope
from a dead stop using 180 mm cranks seemed to have no effect on the
hub. I never felt any slippage in the hub, though by the end of the week
the chainring I had used was showing signs of extreme stress.

The factory specs on torque state that the chainring should be at least
twice as large as the cog on the hub, and this is how it was set up for
this test, with a 19t freewheel and a 38t chainring. With this
combination, the lowest ratio available gives the equivalent of a 1:1
gear, in which the rear wheel rotates once for each crank revolution. On
this bike, a Redline Monocog Flight with Rhyno Lite rims, this
translates to a 26" low gear. With the 350% range of the hub, this means
that the highest ratio is a 91" gear - all in all, high enough and low
enough to be useful in almost all situations. I did find myself using
the full range, and I never felt that I really needed more, though I
occasionally thought I might want it.

One of the main advantages of any internally geared system is resistance
to extreme weather and dirty conditions, and the NuVinci is no exception
to this. At the end of my week, I took the time to clean around a half a
pound of road grit off the bike, and had to open the Euro style BMX
bottom bracket to let the water out. Through all the slop that winter
dumped on it, the hub remained impervious, and chain maintenance was the
main concern, though there was never any question of derailing, as the
chain line was essentially the same as any BMX drive train.

Overall, I would say that the hub performed excellently, and definitely
lives up to its promise as a unique and revolutionary technology. The
one feature that is lacking is some sort of protection for the shift
box, which is mounted on the right side of the axle, and could be
vulnerable in a crash, or when parking in a bike rack. It should be
possible to modify a derailleur guard to prevent such damage, but it
would be best if the manufacturer were to provide a guard. It is
possible that future versions of the hub will be lighter, as well, but
the current weight is not inappropriate for the comfort, city, commuting
and cruiser style bikes that it is likely to be installed on. The great
news is that we have continuous shifting at long last, and it is not
only reliable, it's fun!




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