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Sunday, July 15, 2018

About my trikes, the heart

Local letterbox, with decorative steel support, and

another one, and

yet another one. This style of fence and post decoration has been celebrated in the local Green Bins artwork on Hoddle Street, which is still there and thriving.
Letterbox and house number, now that's thinking!
Lego house number and letterbox, that's really thinking! 
Bluebower Letter box with diorama

Bluebower Letterbox with lego diorama.

Bluebower #3

Bluebower #4

What's with all the letterboxes, then?  It's really just showing off some local creativity and everyday playfulness in our neighbourhood, and to draw attention to their similarity to the ideas present in the Bluebower letterboxes and some of my trikes.

Just like in "about my trikes, the bones" on the structure of my trikes and lack of chain stress in the frame, there is an appeal to a higher theory here, and that is contained in Jules Pretty's "Manifesto for the Green Mind" which is an anti-sloth, pro-happiness, pro-learning and pro-environment wake-up call. It calls for regular physical activity outdoors, continued cognitive engagement  and socially based activities and creativity low in material consumption yet delivering health benefits. 

After picking out photos of my own creations, a phrase welled up for some of the enabling tools (bluebower letterboxes, my trikes when they go on sale) for this creativity and that is "gifts that keep on giving".  That is, like learning to play the ukelele say, these are things that don't stop, and can be played with, learned about, and used to provoke satisfaction and discussion and interest and friendship.  A certain amount of vanity needs to be thrown away, your diorama, your ukelele playing, your bike side panel, your bike pedal will never be perfect and some of your friends might disagree but what the hell, life's for living. Or something. 

That is probably enough rabbitting on for now, photos of some bikes and trikes and their customisation follow, which is just the same as my usual blog, but a bit of a summary and showcase.

Regards

Steve Nurse






















Tuesday, July 10, 2018

Audax 200k ride, Cobram

Outside Cobram Hilton

Audax ride start

My fixed bottom bracket front wheel drive, Simon's moving bottom bracket front wheel drive

Road to Berrigan


Apple Supply

Fuel tank with pizza and apples

Refuelling

Still trying to perfect the on-bike selfie, the colourful background keeps getting in the way of the blurry thumb covering the lens.

Waaiwa Post Office. Zoom out a bit and you would see sheep and horses.

A 2d selfie, just before sunset near Namurkah

Brevet Card, Job Done.

Ambience Cafe Cobram, from left to right in foreground Simon, Rodney, Ann, Peter

OzHpv committee meeting in Cobram. We struggled through the adverse conditions which included a few wasps and hoards of pesky noisy gossippy nearby but mostly friendly Audaxers. Left to right, Richard, Simon, Dome, Ian. Tim is in the meeting by the wonders of modern communication, Simon's circled black phone was on speaker mode.

Hi

A few months ago, the OzHpv committee planned a meeting for July, and it was suggested that it coincide with an Audax ride, and we chose Rodney Cruz's North and South of the Murray rides around Cobram as the best alternative. Dome lives in Western Sydney, Richard in Tungamah only 50k from Cobram, Tim, Simon and I are in Geelong and Melbourne,  so Cobram seemed fairly central.

The weekend and meeting went exceptionally well, having got back and had a few days to recover feel quite refreshed.

So I went up to Cobram on Friday, and arrived in time to set up my tent at the Willows caravan park, then drive out to visit my Dad's cousin and her husband, Mary and Geoff.  Mary and Geoff are both well, in their late 80's and still living on the farm which their son David runs.

I drove back into town and bumped into Dave Harrington who was pootling around the caravan park looking for fellow Audaxers, and then Ian Boehm, staying in a nearby cabin. We arranged to meet at a pub for dinner later.

Then followed "First dinner" of bread and left over casserole, microwaved in the caravan park's outdoor kitchen microwave with some friendly locals mingling around.  After meeting Ian and Simon in their cabin I was bumped up to first class, a couple of people had withdrawn from the cabin due to injury and family issues, and I had a bed! in a heated! cabin with a colour! TV and microwave and kettle and other modern accoutrements.

Second dinner was pizza and a few beers at the pub with Dave, his partner Ann, Simon and Ian. I really couldn't eat all the pizza and drink all the beer, I was full up and felt a bit sick but wrapped the left over pizza in some serviettes for later consumption.

Up early next morning for the ride (link to route map) , and we met up with a few familiar crew at the start in central Cobram.  Squawly winds had been predicted and they duly arrived, cold and with a small amount of rain from the west.  So the ride to Berrigan (mostly North) was ok, but turning left to go to Finley it was headwind all the way.  Luckily I was riding with someone then and we took turns pushing into the wind.  After morning tea in Finley, it was a solo ride for me the whole way, although we had a bit of overlap at the Cobram lunch stop, the Ambience Bakery.  The hard bit of the second 100k was from the start of Blarney Road, about 24k of headwinds diluted only by roadside trees and crops.  Right at the start there were lots of apples lying on the ground, and I helped myself to some and that was most welcome.

Here is the video  I took near Waaiwa, a town with a very small post office!  I ended up getting back in to Cobram about 8pm, which was not bad I reckon.  My gps had been (gasp, shock) useful, and I'd been able to light it up with my helmet light when required, so that pleased me a lot.

Next morning, after an evening spent watching the Tour De France start, we packed up and reconvened at the Ambience Cafe, first (9am) to catch up with some fellow Audax ne'er do wells, and then 10am for a very productive Ozhpv committee meeting.  The Ozhpv Challenge 2018 is on, woohoo! If I keep up the Audax riding I might even be really fit for it.

Thanks to Ian and Simon for the upgraded accommodation, and to Rodney for organising the Audax ride.


Monday, July 9, 2018

About my trike, the bones.

Hi

Last year, I finished an industrial design master's degree at Monash University, and as well as documenting 6 leaning trikes I'd made during the study, wrote an entire thesis about them and what makes them tick. The thesis writing was actually all but finalised in December 2016 and didn't really include much about chain stress on recumbent bike frames, and minimising chain stress is part of what my designs do.

So sometime last year I started writing stuff about chain stresses in recumbents, and bounced some of the ideas off my friend George Durbridge.  I written a draft by March 2017, emailed George, he wrote back, I then sat around on my bottom for a while attended to other important matters and eventually got around to redrafting, then sent it to George again and eventually it seemed good enough to send to the impressive-sounding World Human Powered Vehicle Association technical bulletin at hupi.org .

Here is some of George's correspondence, this bit dates from March 12 2017, published with his permission

"Steve,

I'll drop off your paper, with a lot of illegible notes, and I expect
I'll see you tomorrow. In the meantime, a note on something you may
have taken for granted, but which a lot of readers will need help to
work out for themselves.

How great is the material cost of chain stresses, and what other costs
are there?

The material cost is low. Chain stress mainly appears as bending of the
frame in the vertical plane or, with your bikes, of the fork. There is
a secondary element of lateral bending, but it is clearly much less
than the vertical bending. Those elements of the frame have to be
strong enough to carry the weight of the rider, which acts in the same
direction, and is of the same order as the greatest force the rider
will repeatedly apply to the pedals. It must also withstand bumps,
which may easily reach 3g.

Chain stress is recurrent, so the frame must be overdesigned by a
factor of 3 to resist fatigue from millions of cycles (literally), but
3g bump stress is more or less one-off, with not much fatigue effect.
So the metal needed to resist chain stress is more or less the same, in
amount and location, as the metal already needed to resist bumps.
Obviously, one turn of the pedals (but not millions) may coincide with
a pothole, so the frame must be able to resist 4g (more or less) but
that's a small increment.

The fact that chain-stress appears mostly as vertical bending is
counter-intuitive to me, but it seems settled. Experiments show that a
round or square tube bends much more vertically than sideways under
chain stress. New (GT20) and old (Linear) designs of monotube recumbent
deal effectively with chain stress by using a deep but narrow main
tube. These are fast machines uphill, although your calculations
confirm my notion that such a frame is much weaker in lateral bending
than in vertical bending. Properly braced extended diamond frame
recumbents, like Longbikes, deal effectively with chain stress, using
no fat tubes, but the twin tubes are always top and bottom, never side
by side, except in the Midnight Racer, which seems to have been a
disaster of a frame.

This is even odder when you reflect that chain tension roughly balances
leg push, particularly the right leg.

But the major cost of chain stress isn't the weight, bulk or expense of
additional metal in the frame. It is power loss due to flexing. What
the numbers may be, I don't know, but it is certain that whippy steel
frames bend quite noticeably with every hard push on the pedals, it
follows that they store energy which would otherwise have been used to
push the bike along, and it seems that they unwind in a way which
returns no work to the transmission (or at least, much less than they
squirrel away). The cost of using cross frames on trikes is that we
are, in effect, bending a long tubular leaf spring with every push on
the pedals, and letting it unbend freely. On the other hand, it is
common experience that stiff frames are efficient and fast.

(Locally, the shift to stiff frames began with space frames for Pedal
Prix racing and velos, and moved into monotube frames with the Anura
and Magnum, which have rectangular and round main tubes, respectively.
They show no particular signs of having been designed for stiffness or
efficiency, other than keeping them reasonably light. Whether stiffness
was a cause or an effect of moving to aluminium construction, or just a
happy synergy, I don't know: after all, nobody talks about the sporting
potential of those trikes.)

How does this reflect on your paper? To make your case it is essential
to quantify chain stress, how it interacts with leg forces, and how the
resultant affects frame design, at least roughly. It would be good to
mention power absorption, which matters a lot to cyclists and to anyone
writing for cyclists, probably more than for an engineering or design
reader base. I suspect that chain forces are much less of a problem
over the short lever of your front fork than they are over a long
monotube.

This does raise the issue whether you need to think about forks
designed for this use, though that's not an issue for this paper. There
is also an issue about how chain force and leg force interact in your
designs.

George

On Fri, 2017-03-10 at 10:38 +1100, cesnur (the at thingy) iimetro.com.au wrote:
> Hi George
> Here's an article I wrote about chain stresses in recumbents, could
> you have a read and tell me what you think please?
> Hope you are well.  I am through all of my master's degree written....... etc. etc."


So the first draft was sent to hupi on January 11 and it took a few months of back and forthing to get it published online.  I took onboard the editor's (Theo's) very helpful suggestions about putting in the stress affects of electric motors on the frame and there was quite a bit of work to do with graphics in vector and bitmap format but we got there eventually, and the article came out on May 21.

At this years Spezi show in Germany, there were a few timber bikes of the "Albatros" type ridden to the show, and Bentrideronline captured them. Also my friend Simon Watt rode 100k on his newly faired Albatros last Saturday, I'm showing a few pics here so you can sit back and think about where the chain stresses might apply and how that relates to the various materials used as you read the article at your leisure.
Spezi 2018, Germersheim Germany, laminated timber frame Albatros (bentrideronline.com)

Spezi 2018, Germersheim Germany, bamboo frame Albatros (bentrideronline.com)

Cobram, Victoria, Australia, diamond frame bike, my FWD trike, Simon Watt's Albatros at the start of 100 & 200k Audax rides, with Rimas (I think). Ian, Simon and Dome.

Cobram, Victoria, Australia, Simon Watt's Albatros with newly acquired front & rear fairings.


So there you have it, all neatly packaged, the bones of my trikes.  Next in this very small series, "about my trike, the heart". My trikes don't have an identifiable liver, or pancreas so I think I will just stop with the blog series there.

Regards

Steve Nurse