Thunderbolt with wide range gears and more


Doug Goncz

Hello, arbr folks. I haven't been by here in ages.

My Thunderbolt has 24-35-51 / 34-28-23-19-16-13-11 double step gearing with
657% of range. 21 speeds with 10 duplicates. 11 widely spaced gears. I do not
follow the advice to maintain a constant pace. Rather, I combine pace and
pressure to maintain efficiency, an approach well supported in the experimental
literature. I do not have a power meter.

I used a Sugino XD tandem crankset with TA rings. The shift pins and ramps help
that very small middle gear work well with the others, but it had to be moved
inward by 1.2 mm to work. As supplied by Bikes@Vienna, it had only 14 speeds
with 5 duplicates and less range than stock. They just couldn't finish the job
and John Brunow there has refused to answer my many emails trying to resolve
the problem. Nobody else at Bikes@Vienna handles the email. Let's not go on
about the shop, let's talk about the bike.

It could use another 0.6 mm spacer under the 51 T chain ring. It's reasonable
now and I can spin 51/11 down any hill, and push 24/34 up the same hill.
Yesterday I climbed out of Bluemont Park to the top of Upton Hill via Lockwood
House, finishing on turf at damn near a 45 degree angle. I had to speed to the
slope to make it and on the slope the slick slipped, so when I build in the
disk brake hub I am going to a 1.75 rim and a little more knob.

I mated a Big Cheese BMX chain ring spider to the disk brake hub by drilling
from 7/8 to 1 1/4 with a Unibit and having Jensen finish the bore to 33 mm. Or
was it 34? Whatever. I applied a 48 T chain ring and a loop of chain to make
the boring setup compatible with the standard three jaw lathe chuck. This
reduced the price of the boring job. Then I bought a set of 10-32 transfer
punches from Small Parts and screwed in three. I applied the Cheese and added a
large socket to distribute the force, then whacked it. I drilled at the marks
1/16 HSS at 3000 rpm, then enlarged these holes to 7/32 to clear the 5mm SHCS,
which are close to 10-32. I installed three screws in the holes and whacked it
again, drilled out those three, and ended up with a hub with cogs on both

On the left rear, a chain goes to Northern Hydraulics's 8 tooth go cart pinion
for 5/8 shaft with integral key, thinned on the lathe at Jensen to 2 mm
thickness for the bike chain. An Ametek servo motor from C&H Sales rated 900
rpm, 30 VDC, 12 A was slotted 3/32 x 3/16 for this key in my mill. The pinion
fits nicely and does not slip. A motor mount made from 4 inch plastic drain
pipe (not schedule 80 PVC pipe) with two bent ears hangs from the Tbolt's seat
stay clamp screws, which were extended to 30 mm length at Home Depot. A
stainless hose clamp tensions the chain and another secures the mounting shell
to the motor. I drew the pattern for the mount in Express PCB, a free drafting
program designed for schematics but capable of scaled output. I glued the legal
sized output to the pipe and drilled and cut to make the mount.

The two screws secure the rack, a Blackburn Expedition rack, to prevent
forward/rearward movement. Grommets are needed there. I cut off the slots on
the rack adjusters and slotted the remainer to suit the Tbolt. The rack is very
nearly level. I can attach my Northern Hydraulics Heavy Hauler wagon for heavy
loads using two climber's carabiner's and intend to use this configuration
again when I pick up a monitor soon.

The wheels are fitted with the OEM supplied ESGE fenders and during a motor
experiment, the motor fell against the rear fender and tire, and the fender
rotated forward, folding in thirds, then amazingly springing back to shape. A
few minutes with a ball peen hammer and you really can't tell it's not new. A
local park has a muddy section after it rains. But that section gives me access
to a really safe route to Bluemont Park. So I slog it out. When it's bad, I
divert to the grassy route; more difficult navigation, but better terrain.

A 110 VAC ceiling fan motor has been fitted to the front derailer mounting post
with a Bike Nashbar adjustable stem and a hose clamp. Jensen machined the
Surplus Center's 10-1134 motor shaft to 5/8 and slotted it for another 8 tooth
pinion. It is driven by a matching 51 T cog. A 52 or 50 T cog might provide
better chain adjustment. The Nashbar stem, which only adjusts by every 5
degrees, was machined on my mill to provide a 120 degree V-seat to support the
motor, and can still be used as a stem. All I did was vee out the cast seat
linearly. I will repack the bearings with oil instead of grease soon, and one
day will rewind the armature with silver magnet wire to further lower the
source impedance and increase efficiency. Since the windings of the AC genny
are on the circumference rather than in the center like the DC genny, it has
lower resistance and should display higher efficiency than the DC genny, which
is good, since pedal power is precious.

Two types of loads can be attached to the AC genny. Both shut down at 80 VAC to
prevent depoling the rotor. The rotor is poled with 12 VDC for about a second.
After doing that, and with the needed run cap in place, it self-starts. If
rotated to a stop with a load that doesn't automatically go off line it will

One load is either an 8 inch white LED signal light made by Dialight and
donated for my experiments, or the innards of a green 12 inch traffic light
made by the same company, purchased through ebay. The two inch square green
phosphor LED board will mount on a bit of foam facing forward for tests, and
the circuit board will be on a similar bit of foam nearby. This forward facing
green light is not a legal marker light, but if a marker light is supplied, is
legal. As a headlight it has a very broad beam suitable for singletrack. The 8
inch unit has not been disassembled and has a fine beam pattern, which will be
smoothed by bead blasting soon. It's a remarkable headlight at 8 watts but it
can't be adapted to batteries. The current controller requires 80-135 VAC. To
use it with an inverter would be hilarity.

The other load is a bank of two R40 reflector flood compact fluorescent units
with an 8 position switch applying combinations of half wave and full wave
power to the lamps providing 10, 20, 30, and 40 watts of load, and ridiculous
amounts of light. They are mounted in desk lamp shells from Home Depot with
standard medium base screw in sockets. The shells are riveted to Space Bars.
The Space Bars are spliced in the middle with rivets and tubing inside. They've
been milled out a bit so they can clamp side by side to the handlebars. They
use an internal T-nut for clamping.

A white F4T5 tube light using 4AA alkaline cells has been fitted, glued to the
back of a wide view convex mirror, both supplied by J.C. Whitney. It wiggles
and I need to remake the Lexan mirror mount I made in aluminum or magnesium to
prevent the wiggle. But it's the best rear view mirror I have ever had on a
bike. The light serves as a marker for legal riding, and is suitable for less
challenging singletrack, not for high speeds. A linear aperture tube is planned
to provide a horizontal beam with four times as much light. I'll have to mix
red, green, and blue fluorescent paint to get white. This will be painted on
external to a germicidal tube. The output of the germicidal tube may not match
the absorption peaks of existing paints. They usually match conventional black
light tubes, so I may have to mix some phosphor paint.

This light will be added to the rear as a marker using fluorescent red paint in
several layers. This is cheaper than LEDs and may be more efficient.

A Buddy L charger will recharge the AA cells for the lights and for other
equipment from the either genny.

The whole thing is for the US Army's Dual-Use Technology program, and will
likely be commercialized first, then modified to support our troops, who are
resupplied more frequently with batteries than with food some weeks.

It's a mobile power station that turns Gatorade and Nutri-Grain Muffin Bars
into 110 VAC, regulated 6 VDC, and 10-15 VDC floating off of an ultracapacitor
bank storing 9 watt hours of energy that can be delivered at 3600 watts peak.
And it takes some trails, too. You can ride all day in it and not get a sore
but or tired arms.

pics at

Sorry no pics of the recumbent yet. Just the machining, the machine, and the
devleopment bike, a Peugot moutain bike.

Aren't those lights amazing? Two 15 W dimmable CFL units in broad daylight on
the Cross County Trail, and they washed out my CMOS camera! It's specifically
designed to let you see somebody's face when they sit backlit in a sunny
window. I think it has 120 dB of light range. And they washed it out.

Any time you are in Northern Virginia, look me up, give me a call, and visit my
home shop. You'll be welcome there.


Doug Goncz ( )
Student member SAE for one year.
Loves in my life:
Dona, Jeff, Kim, Mom, Neelix, Tasha, and Teri, alphabetically.
So that is who I spend my time with.

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