Maiden Voyage - GB4 36 Custom

So first, I’ll confess my shame. My new GB4 36 arrived from U-Turn last
Friday, and it took me 5 days to get to its maiden voyage. But last
night was the night, and the journey was only sweeter for the
anticipation. I’ll get to a more formal review later in the proper
forum, once I’ve knocked off a hundred miles or so and can speak from an
educated standpoint. This post is just about the joy and challenge of
taking a super-fine machine out for its first journey.

Getting it ready was pretty straightforward. The packing was great,
everything came through in great shape, nothing was sticking out of the
sides of the boxes, and all that really needed to be done was install
the pedals, mount the wheel, tighten down the bearing holders, and
program the computer. John Childs was kind enough to come over on Monday
night and help make sure I didn’t botch the wheel install, but that was
mostly just a good excuse to have a couple beers and down some of
Marie’s excellent homemade shepherd’s pie. George’s bearing holders are
very precise, and the wheel dropped in beautifully. By that point it
was getting dark, so I knew a ride was out. That said, you can’t have a
brand new custom 36 sitting there assembled in front of you and NOT give
it a try. I was worried, though…I hadn’t been on a Coker since January,
and I really didn’t want to blow my first free-mount attempt. Call it
superstition, but I wanted to nail the first mount. The worry was
doubled having Childs there, because he’s the person I wipe out in front
of the most. Turned out to be a non-issue, even with him watching. I
backed it up half a turn, walked forward, and hopped right up the first
time. Good Luck Omen #1.

So due to other commitments, I couldn’t ride Tuesday…another agonizing
delay. Finally Wednesday came, I got home from work, and after a few
laps around the neighborhood to get things adjusted and snap a few pics,
I was off. About time! I headed right for a long gravel trail out of
my neighborhood, trying to think through the ideal route for a test
drive, with some good climbs, steep downhills to test the brake, and
some gravel and dirt trails just because.

The first section was pretty flat, giving me a chance to check out the
basic speed and handling. The GB with U-Turn’s wheel and higher quality
bearings is much easier to pedal than my stock Coker was. Very smooth
and very fast. In my previous Cokering, I couldn’t really imagine
shifting to shorter-than-stock cranks, but I found myself thinking about
that very quickly here. I pretty quickly got up to max pedal speed (for
me), which according to both my fear factor and the computer was faster
than I’ve ever gone by about 3 mph. I thought the wider hub would
really take some getting used to, but it felt comfortable right away.

After a short paved section through the edge of a thick wooded area, the
path I was riding comes out of the trees and takes a sharp turn to run
through a large grassy field under some big power lines. I came around
the corner at about 5 mph and rode right into a group of three deer that
were browsing the grass at the side of the path. They were literally
less than ten feet in front of me, and if they hadn’t jumped pretty
quickly, I had a real chance of either hitting one full on or UPD-ing
into one. But not being on a 36” wheel, their ability to quickly
accelerate saved the day. Surprisingly, they really didn’t get
spooked…they jumped about 30 feet away, then stopped and went into a
slow walk into a stand of trees. This gave me the opportunity to
dismount and snap a couple pics. It was quite the adrenalin charge to
get so close to this wildlife on my uni, and I’ll consider it Good Luck
Omen #2 for my new GB4.

Flats, speed, and wildlife out of the way, I headed for some hills. As
part of my Moab prep, I had switched to muni riding exclusively after
January. With a four month hiatus from the big wheel, I was a little
worried about climbing with it, but was very happy to find that the
progress I’ve made in climbing on my muni mapped right over to the 36.
Hills that used to leave me sucking wind if I could climb them at all
seemed much easier. The GB/UT prototype handle provided a very solid
platform for pulling, and there was no noticeable wheel flex during the
climb. I did seem to hit the side of my thighs a couple times on the
crown, but that was pretty easy to adjust for.

My braking skill from my muni—unfortunately—did not transfer over quite
as well. I made the mistake of having my first downhill brake attempt
be on one of the steepest paved hills in my neighborhood:
http://gallery.unicyclist.com/albuw44/IMG_0473. I can get down this no
problem on my muni, with or without brake, but on the 36 I got to about
the halfway point and things started going wrong. Braking on a 36
requires a much more delicate touch, and it’s also a lot harder to make
micro adjustments to make up for inconsistent application pressure. At
one point, things got wobbly, I squeezed the brake tighter, started to
go over the top, released the brake, and had the GB shoot out from under
me. It bounced and rolled, I just bounced. Wipe-out #1…there always
has to be a first one, right? Over the rest of the ride, I had a chance
to practice braking on some longer hills also, with sections of varying
steepness. In the process I UPD-ed backwards and over the top, the
latter resulting in a nice stripe of rash above my knee. George and
U-Turn: you’ll be glad to hear that the front of your handle provided
sufficient protection for the computer. The uni went down hard, and
everything was protected. By about my fifth descent I was starting to
get the hang of it. Next ride I’ll be going back to that little hill in
the above link, and I’ll make it down. Then I’ll turn around and crank
my way up it. You can only take so much lip from a stupid hill…

Since I was falling off anyway, I took the opportunity to check my cycle
computer. Seven miles… I was only about a half mile from my house at
this point and was feeling kind of tired from the climbing and
wipe-outs. I started to head for home when that little Fred Flintstone
landed on my shoulder, whispering “If you don’t get to double digits on
your Inaugural Ride, you’ll be a Wimp For Life (WFL, or “wiffel”).
Yeah, I thought, you’re right Fred. Can’t limp home now without hitting
the decade mark…better get in some more climbing and braking practice.
Turned out to be a good idea, since otherwise I’d have missed a really
nice sunset.

One thing was a bit off: I felt like the uni was “pulling” a bit to the
right, which is to say I felt like I was having to lean slightly to the
left (i.e. pushing my hip slightly to the right) just to keep going in a
straight line. I’m sure it’s just something slightly out of adjustment,
and that something might just be my brain. The wheel is absolutely
true, and is a work of art, so I’m ruling that out. Not sure what else
might be a factor. Airseat inflation? Seat angle? Wheel housing in the
bearing holders? Any recommends from the pros on why it might feel that
way?

I’ve created an album of shots of my GB4 36 Custom, and it can be found
as the last album at this link: http://gallery.unicyclist.com/albuq62.
There are some shots in there showing the arrival, boxes, unpacking,
etc.., plus the final assembled road beast, deer in the trail, etc. All
in all, the Maiden Voyage was a great success. The GB4 36 rode like a
charm, the U-Turn wheel and overall build-up is great, I crashed it good
a couple of times, I bonded with deer, and I made it to double digits
even though it brought me home after dark. It was a good day. Total
miles: 10.3; Average speed: 7.6; Top speed: 16.3; total pedaling time:
80 minutes. George and Dave: you have built a wonderful machine, and
I’m proud to own it. What a ride! I’m looking forward to the many
thousands of miles ahead…

Tom


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tomblackwood - Registered Nurtz

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If you thought seeing the deer was a kick, wait till you do a night ride
with a bright light. Then you'll see all sorts of glowing eyeballs
looking at you from the sides of the trail, from the woods, from up in
the trees, everywhere. It's freaky.

The problem with the uni feeling like it is pulling to the right can be
due to several things. On the Coker I've found that it is usually due
to something being out of center with the seat. If the padding in the
airseat gets out of kilter and leans one way then the uni is going to do
the same. We'll have to find out how U-Turn put the seat together and
how the inner tube is stuffed in there. Maybe it's a little lopsided.
It could also be due to needing to get used to the wider hub. We'll
see.

My max speed on my GB4 Coker is only 15 mph. I have no desire to push
it beyond that right now.

Say, talking about max speeds. What did you end up setting your cycle
computer at for wheel size? Maybe your setting is making you go faster
than you actually are. There's no way that you can be faster than me.


--
john_childs - Guinness Mojo

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Thanks for the nice writeup and photos, Tom.

It's nice to see the crash protection is working well. It has worked
well on others and there's some delicate stuff up there (Magura brake
cables, cyclometer head, headlight). The handle was designed
specifically to provide crash protection for those three components.

You will quickly get used to the brake. I did the same thing with mine
- I went flying about 12 feet horizontally. Now I use it all the time
(when I'm functional).

As far as the twisting goes, there are several things to think about,
not in any particular order:

1. You may not be comfortable riding at night, so that your body is
drifting into an "easy bailout" mode. More rides will fix this.

2. You may just need time with the new configuration. More rides will
fix this.

3. Your seat may be a little high, so that one of your legs (probably
dominant) is optimizing itself at the expense of the other.

4. The seat may not be on quite straight.

5. As John said, there may be seat support issues. These seats are
really tricky and very individual. However, at first just play with the
air pressure, because reconstructing the internals is a lot of work.

6. Find neutral ground to ride on (that is, non-sloped, non-crowned hard
surface) and see if the problem still exists after riding for an hour or
so.

All but the second half of #5 require little work but riding, so I
recommend doing them first. However, if it should come to that, you
might at first revert to a "normal" air seat using a dogbone (I did send
you one, right? If not, I will) and simply replacing the innards rather
than try to rework the innards. Then you can try the innards again
later without having torn it apart (for the non-Tom Blackwoods, the
"innards" of the seat include a constrained air tube plus Miyata
foam).

I look forward to more excellent writeups!


--
U-Turn - Member of Generation XO

Weep in the dojo... laugh on the battlefield.

'29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)

'Strongest Coker Wheel in the World'
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'New York Unicycle Club' (http://www.newyorkunicycle.com)

-- Dave Stockton
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tomblackwood wrote:
*One thing was a bit off: I felt like the uni was “pulling” a bit to
the right, which is to say I felt like I was having to lean slightly
to the left (i.e. pushing my hip slightly to the right) just to keep
going in a straight line. *


I find this quite interesting as I always drift to the left. This is
regardless of the surface I am riding on as I do the same whether I am
on a nice flat hall floor, on tarmac or on paving.

I have checked the seat and I'm pretty sure it is on straight. I've
been experimenting with seat height and I'm pretty sure I have that
right. I may, of course be wrong on both these points, but at least I'm
riding far enough to notice the drift (4 pedal strokes).

Is this a characteristic problem with cokers or just something that you
notice quicker because you go so far with each pedal stroke?

Anyway - a very nice write up of what sounds like a fun ride.

Jayne


--
Jayne ZA - Learning to ride on a Coker

Being a statistician means never having to say you're certain


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john_childs wrote:
*What did you end up setting your cycle computer at for wheel size?
Maybe your setting is making you go faster than you actually are.
There's no way that you can be faster than me. *

Well unless you botched the chalk marks during the roll-out, it should
be correct. The tale of the tape was 110 inches, which according to the
online conversion engine at sciencemadesimple equaled 279.4 cm. I
rounded down to 279, which might be responsible for the discrepancy.


I was stunned by the reading also...as I noted, it's 3+ above my
previous fastest. But everything else looked right....I've ridden the
route before and the mileage made sense. Maybe we can try side-by-side
this weekend and check the calibration.


--
tomblackwood - Registered Nurtz

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tomblackwood wrote:
*
Well unless you botched the chalk marks during the roll-out, it should
be correct. The tale of the tape was 110 inches, which according to
the online conversion engine at sciencemadesimple equaled 279.4 cm. I
rounded down to 279, which might be responsible for the discrepancy.


I was stunned by the reading also...as I noted, it's 3+ above my
previous fastest. But everything else looked right....I've ridden the
route before and the mileage made sense. Maybe we can try
side-by-side this weekend and check the calibration. *
If you want to go twice as fast, or three times, I have some extra
magnets here...


--
U-Turn - Member of Generation XO

Weep in the dojo... laugh on the battlefield.

'29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)

'Strongest Coker Wheel in the World'
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tomblackwood wrote:
*
Well unless you botched the chalk marks during the roll-out, it should
be correct. The tale of the tape was 110 inches, which according to
the online conversion engine at sciencemadesimple equaled 279.4 cm. I
rounded down to 279, which might be responsible for the discrepancy.


I was stunned by the reading also...as I noted, it's 3+ above my
previous fastest. But everything else looked right....I've ridden the
route before and the mileage made sense. Maybe we can try
side-by-side this weekend and check the calibration. *

I've been using Nathan's measurement of 2776 mm. His number came from
measuring 3 revolutions and includes riding wobble so it gives road
speed rather than wheel speed. But that number was on a stock Coker
wheel. I'm not sure if the Airfoil rim will make a difference.

Some threads about Coker rollout distances:

'Nathan's measurement' (http://tinyurl.com/2bxu2)
'Calibration thread started by Klaas Bil' (http://tinyurl.com/376q3)
'Calibration thread started by Ken Fuchs' (http://tinyurl.com/23o6a)

It's too early in the morning for me to do any math. I'm curious about
how much of a difference in MPH your setting of 2790 mm and my setting
of 2776 mm would be if we were both going the same RPM (cadence). I
suspect it wouldn't be much. Probably less than the resolution of the
cycle computer. Maybe. But I don't feel like doing any math to
verify.

Your number is close to the measurements for no wobble while mine is
close to the measurements including wobble.

I use the Google calculator for conversions and calculations. I love
the Google calculator.
'110 inches in mm' (http://tinyurl.com/2wu2b)


--
john_childs - Guinness Mojo

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john_childs wrote:
*I've been using Nathan's measurement of 2776 mm. His number came
from measuring 3 revolutions and includes riding wobble so it gives
road speed rather than wheel speed. But that number was on a stock
Coker wheel. I'm not sure if the Airfoil rim will make a difference.*

Seems to me there was plenty of wobbling going on as tried to get that
one full revolution while clinging to my wife's truck...

Maybe on our weekend ride we can find a measured mile someplace and see
how our computers compare against it. I don't want to go too fast...I
just want to set me computer so I can remain a little faster than you.



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tomblackwood - Registered Nurtz

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How are we going to keep up with you on the Iron Horse Trail with you
going so fast and us trying to dodge a herd of wild animals chasing you?
I can tell you without seeing it that the seat is too low. Please fix
that for me before I ride it.


--
harper - Statuesque

-Greg Harper

B L U E S H I F T

"Stoke your own thread as much as you see fit, no problem." - Klaas
Bil

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"john_childs" . com writes:

It's too early in the morning for me to do any math. I'm curious about
how much of a difference in MPH your setting of 2790 mm and my setting
of 2776 mm would be if we were both going the same RPM (cadence).

Less that 0.1 MPH at riding speeds.

Ken