Friday, January 24, 2014

Prepping for the second bike (part 1/3)

A little cabin fever has been setting in and I'm ready to start work on the second bike.  Normally I would work out in the barn, but we are in the third spell of sub zero temperatures, so I took some time to find a flat, level spot on the basement floor.
Using a level and 6 foot wallpaper straight edge to find a good section of floor.
If the floor is bad, it's also possible to build a low table that is flat and level.

Then I attached a prop arm to the wall framing with only one screw so that it would pivot, stood the project bike up level, and put some weight on the end of the arm to press down on the bike.
The bike standing up vertical for measurements.

The main goal of this project is to extend the rear wheel backwards to make room for a large cargo rack, but there are a few smaller goals.  I used low pedals on the first bike to make it easier to stand at stop signs and lights, with the crank centerline 10 inches off the ground, which resulted in the pedal centerlines being 3.5 inches off the ground.  It turned out last summer that I never caught a pedal when leaning in a curve, but did hit the ground a few times when riding off road with the bike.  This bike needs to be slightly higher.  Another factor is the steering head or stem angle, (the head is the frame tube on the outside, the stem is the fork tube on the inside, both should be the same angle if the bearings are ok), as I want this bike to have slower steering.  Most mountain bikes are using a steeper angle (72-75 degrees from horizontal) with minimal trail for a fast steering, so that riders can steer around rocks in a split second.  I would like the steering to be fast enough to avoid obstacles that the rider notices, but when they don't see something the bike should be able to ride over it without falling.  I also want a bike that will track straight when the rider says "Look at that cow" and the kids on the back turn.  I'll cover a bit more of steering geometry in the next post.

The head angle is 68.5 degrees.
This is a magnetic digital angle gauge that woodworkers use to set their tablesaw blades.
It's cheap enough at $25, but it has some accuracy issues that I'll write about in another post.

The stock crank height is 11 3/4".

The stock pedal centerline height is 5".  

With the rear wheel removed and the frame propped up 1.5" lower at 10 1/4" crank height.

This gives a new pedal height of 3 5/8", which is 1/8" higher than the first bike.

The lowered head angle becomes 64.7 degrees.
Hmmm, is this okay?  It should be slow steering, but maybe too much.  I know that it is possible to ride a bike with the front fork sticking way out:

Captain America bike, from Easy Rider, Photo credit: Business Wire
I was hoping to not have to cut and reweld the downtube. We'll have to measure the front fork trail in the next post.

Sunday, January 19, 2014

Year end report

A few days ago, a letter about solar electric cargo bikes that I had written to the editor of Home Power magazine was published:
Photo credit: Mary Holland, author of "Naturally Curious:
A Photographic Field Guide and Month-by-Month Journey
Through the Fields, Woods, and Marshes of New England"

This has been followed by a mention in the New Hampshire Sierra Club newsletter:

It's made me stop and think about the huge response and all the people who have helped with this bike.  In the last year it has been to:
-Hartland 4'th of July parade (as a town energy committee project)
-Woodstock Sculpturefest
-Two Rivers Ottauquechee Regional Planning Commission
-Dartmouth Move In Day (as part of the Upper Valley Sierra Club)
-Sustainable Hanover Transportation Expo
-VPIRG / Vermont Toxics Action annual conference
-VECAN town energy committee annual conference
-several smaller outings, such as farmers market booths
There have been a few people who helped at each event, and there are also almost a dozen people in town who donated bikes, as well as two welders who put part of the bike together while I was busy with other work.  In all about 3 dozen people have directly helped, and I'd like to say thanks to all of you.

Currently I'm working on the design of the third bike, (mid winter is a good time for design), and will soon start working on the next frame.  Plans are being worked on for an Electric Vehicle day and 2 festivals next spring, and I also hope to start the loan program that I didn't get to last summer.  There are also some blog posts I'd like to write about on the front fork, aerodynamics, the bottom bracket, wheel size, human power capacity, the ELF, and E.ON, but it has been more about meetings and planning lately.

I'd like to mention some local news for readers in the area- the Bellows Falls Community Bike Project, ( ), held a planning meeting last week and 14 people showed up.  Bonnie Anderson is trying to set up a bike rebuilding program using donated bikes, and sell them at low cost in the community to encourage biking.  There is also a work program where hours can be traded for bike stand repair time or bikes.  She is being helped by Todd Ward (shop manager), Tonia White (VP), and Gary Fox (treasurer).  They have an after school program to teach kids how to work on their bikes, and are hoping to set up a town bike share program too.  Good stuff.  One nice part is that Todd is enthusiastic about electric bikes and utility bikes.

Friday, January 10, 2014

Bicycle chic

As Marc van Woudenberg has written in his blog Amsterdamerize, bicycling culture is man made.  As I've been studying bikes, it's been fun to compare cities:

Photo credit: Marc van Woudenberg, Amsterdamerize
"Bicycle Cultures are Man Made", guest post for the European Cyclist's Federation

Boston is so full of youthful idealism, with so many colleges, and working away at Bikes not Bombs , (although there is still some old school MassDOT that sometimes ignores everything but "Level of Service, Throughput, and Crash Barrier Standards". )  But with so many young people it is so sweet:

And then there is nature loving Portland, with mass naked bike rides and riders writing poems about potholes in winter:

The Tiniest Bright Spot

by Jamie Caulley

January —

Followed by the quirky, macho, damaged charm of Bike Snob, NYC, who obviously loves the pothole poem but can't admit it:

NYC also has Casey Neistat:
Video credit Casey Neistadt
New York, you gotta love it.  See my earlier post "Maybe sports cycling isn't all there is?"

But then you get to the pros - Netherlands - 16 million people with 20 million bikes riding 200 billion km per year with style, and this is what you get:

The Cyclists from Thomas Collardeau on Vimeo.         Music: Ratatat- Loud Pipes

It all depends on what you want.  "If you build for traffic and cars, you get traffic and cars.  If you build for people and places, you get people and places."

Sunday, January 5, 2014

Freewheels and bearing drag for a mid drive

Santa was very nice and brought lots of mid drive presents.  Most of these pieces are meant for the third bike, as the second bike will have a simple direct drive hub motor in the rear wheel.  There are about half a dozen ways to connect a motor in the center, and these pieces give me a chance to experiment before committing to a design. The general idea is that you don't want the motor spinning when pedaling, nor the pedals spinning when the motor is running, unless the rider wishes to use both.  This requires at least 2 one way rotation devices, such as freewheels or one way bearings, and fitting it all between the pedals is a challenge.  Most mid drive bike motor manufacturers replace the standard bottom bracket with a special casting with the drive train inside.  For those doing it on a smaller scale, a motor can be connected three ways:

-left or right side of rear wheel using a single speed gear set with a large wheel sprocket, (this works well for a larger 4000 to 8000 watt motor)
-in the chain before the rear derailleur, which gives about a 2.2x range from high to low speed
-before the pedals, which gives about a 3.5x range, (this is the one I'm aiming for)

A manufacturer using a new casting can use either concentric cranks or offset shafts to separate the motor and pedals.  This is not an option here, and although the motor will be remotely mounted, at least one freewheel and an extra sprocket must be mounted on the crank.  (If both freewheels are placed there the cantilevered load becomes a concern, and a provision should be made for supporting the outboard end of the assembly.)  Mounting directly on the crank arm using the common freewheel 1.375" x 24 tpi thread saves some space:

The threaded right crank arm allows a freewheel to fit in the small space.

Using a flanged freewheel allows custom spiders to be bolted on for sprockets and the second freewheel

A reverse rotation freewheel is usually needed for the second freewheel for the motor connection or it will unscrew, and unfortunately these must be adapted from single speed freewheels as there aren't any flanged units.

Bearings that have either sprags or ramps in them will spin in only one direction, and can be used in place of a freewheel. Since the motor speed needs to be slowed down, a planetary gear set built with a one way bearing is very tempting.  However there are problems with the inside bore diameter fitting around the crank bearings, and also with enclosing the gear assembly, which makes this a more serious solution for someone willing to build a case and/or custom large diameter one way clutch.

I've also collected a few freewheel hubs and freehubs, just in case it looks like a lay shaft would be the best fit.  They would have a problem fitting down in the crank area.

Adapters that could hold the one way devices.

A crank with an extended right side to allow more stuff to fit between the pedals.

As long as all the pieces were loose, I decided to test them for drag.  My general impression has been that freewheels (with a ratchet) have less drag than one way bearings (with sliding contact pieces), but it would be nice to know how much better.  I wrapped a thread around the outside of each piece and pulled on it.  Three forces- the force needed to start the device moving (break out), the force to keep it just barely turning, and the force while pulling as fast as I could while still being able to take a reading, were measured with a small postal scale that had a 0 to 120 gram range.  Dividing this by the thread circle radius gave these torque ratings (the low to high order is based on the average of all three readings, but only the faster speed readings are shown here):

Device                              torque at faster speed  force with a 26" wheel
608 bearing with shields     0.36 grams/cm           0.002 ounce
202 bearing with seals        4.57                           0.032
Southpaw freewheel           14.71                          0.10
DNP flanged freewheel 1     14.88                         0.10
DNP freewheel (clean)        13.97                          0.09
Shimano freehub (clean)     16.28                         0.11
BMX freewheel                   17.41                          0.12
Falcon freewheel                16.06                          0.11
VXB one way bearing          22.58                          0.16
DNP flanged freewheel 2     27.90                          0.19
Planetary carrier hub           27.14                         0.19
Shimano freehub (dirty)      58.14                          0.40

The measurements formed 3 groups:
-the regular ball bearings with 0.4 to 4 grams/cm of drag torque
-the freewheels with 14 to 17
-the one way bearings with 22 to 27 

There were two freewheels that didn't do well.  The second flanged DNP is new and I'm not sure what is going on, as the other one has much lower drag. The Shimano freehub probably has some very old and dirty lubricant inside, maybe even rust, so I don't feel it is representative, just an example of what bad maintenance will do.

The best choice appears to be freewheels, but it should be noted that these are all very small amounts.  The lowest plain shielded bearings cause a drag when riding that is equivalent to lifting 0.002 ounce- not even noticeable, and the worst case dirty hub is only 0.4 ounce drag, which is similar to lifting two pencils.  If a bike was never maintained it might be possible for the front and rear wheel bearings, and the crank bearings to have that much drag also.  The bike would be only a little bit less rideable. The point here is to avoid adding many more bearings while building a mid drive, because maintenance can not be guaranteed.

Thursday, January 2, 2014

Maybe sports cycling isn't all there is?

Continuing the thread I started in the Helmets and Safety post that perhaps there is more to bicycling than sports, here is a very nice short video about New York City cycling I'd like to mention.  Imagine bicycling in a place where we know they drive worse than in Vermont.  Clarence Eckerson Jr. at Streetfilms put together a montage of the change in NYC infrastructure over the last several years.  And this film doesn't even mention the High Line because it is pedestrian, or Citybike.  Impressive.

NYC Streets Metamorphosis from Streetfilms on Vimeo.

I would be remiss if I didn't also mention Janette Sadik-Khan, head of NYC DOT: