News and Events

Keep up to date with the latest news and events of Modular Bikes.

Tuesday, February 13, 2018

Fixing a Flevo Part 2

How it started, from this post
Finished Bike with 24" wheels replacing 700 c size, front derailleur cable and shifter removed and 11-34 drive cog. The remaining shifter was upgraded to a non-indexing model. The heavy rack at the back is gone and replaced with an occy strap which keeps the back wheel from falling down when you carry it. The bike is meant to work with only one of the chainrings, the middle chainring with about 38 teeth.

Test ridden or maybe test wobbled by Aki.....





..... and by me.




Aki and my wife Christine

Part of the payment plan.

New brake brackets can be seen here.  Aluminium plates on either side of the frame, front and back hold the brakes and make the brake mounts independent of holes drilled in the frame.  The front brake was moved from near the derailleur to this new position so it couldn't interfere with the chain.
Hi

My friend Aki came over on Sunday and he picked up his flevobike, passing on a small amount of cash and some delicious home cooked Prawn Crackers as payment.  There have been other posts including this bike including this one from a year ago and this one last August.

Of course we had to have a test wobble!  Most of the fixing of the bike (removing the rack, smaller wheels, moving bottom bracket etc.) helped make the bike suit Aki's smaller leg size and he can now ride the bike ok with only a few goes up and down our street.  He had owned the bike for 15 years without being able to ride it!

I rode the bike along our street but was not so crash hot on the turns.  It was fun.  The cranks were quite a long way back for me but that didn't seem to matter.

Anyway, this post is mainly pictorial, the photos came out quite well with some long shadows and nice reflections in view.

All for now, if you have any questions please ask!

Friday, February 9, 2018

T-Shirt Bike

Selfie next to a gardeners shed in a park near my home.
Raw material, a couple of old t-shirts.  Decided not to use the yellow "Howard Hughes" shirt but instead went with 2 black "PBSFM" shirts.  One had holes in it, the other I retrieved from the pile ready to go to the op shop.

Halfway through cutting, the tshirt is behind the panel it will eventually cover.  The tshirt logo needs to sit in the right spot and the cloth needs to cover the panel.

Probably the best clips to use, but I......
Ran out and used some pink ones of these for one side.
Left hand Side.

Obverse.
Hi

In a few posts, I have shown my leaning trike with cloth panels on it but my choice of cloth has been a bit arbitrary.  For a long time now I have thought about putting something that reflects my character on them and over the last few days I actually did something about it.  I have 3 PBSFM t-shirts and that is a few too many, and the oldest one was full of holes anyway.  So I had decided one was for the rag bag and another for the op shop pile.  But then I got off my hind quarters and made my long-thought about t-shirt bike.  It just needed the old t-shirts fairly roughly cut and held to existing corflute side panels with stationary clips. So I still have a few bike t-shirts of which a great many exist in the world and now also a t-shirt leaning trike of which completely bugger all exist in the world.

It might make the bike look better but it does nothing else for it but make it a bit heavier. But that's what being fashionable is like, you have to suffer for your art...

And by the way I can still wear my other, other, mostly black PBSFM t-shirt while riding this latest creation.  Woohoo!

See you out there

Steve Nurse
 

Sunday, January 28, 2018

Rear View Glasses for Bike Riding

Aki with the glasses in his hand

Mirror panel at outside edge of glasses: "Warning, toy glasses, does not provide protection"
Hi

My friends Aki and George came over last night for dinner.  The excuse was to pass Aki's Flevo bike back to him after fixing.  We didn't get that done as he came by bike, and instead had a barbecue in the backyard and sat around drinking beers in the balmy weather.

But Aki had a trick up his sleeve and when he arrived showed me his rear view mirror sunglasses which he uses for bike riding. They are labelled as a toy (and Aki got them for $3.00 from an Op Shop).  I managed to track them down on ebay here .  They seem like a reasonable option for getting a rear view while riding a recumbent or any bike. But for me they would have to be worn over my vision-correcting eyeglasses which is what Aki does.  Anyway, at about $9.00 including postage they might be worth a try. 

Aki at least had a sit on the Flevo and thought it was ok (It was too big for him before).  Here is the photo of the bike in its new state, it can be compared to those shown here




And while we are on show and tell and to partially explain my nerdish concern about rear vision technologies for bicycles here are a few photos of my current helmet setup.  It has moved on a bit since I started here.  The latest changes are removing some of the corflute and visor right next to the helmet.  This should let air escape easily and help stop the helmet flipping up when travelling at speed, which is inconvenient and definitely embarrassing!





 Regards

Steve Nurse

A Trike Called Fred

Fred Trike
Hi

Recently I read Jun Nogami's blog, Biking in a Big City where he mentions and links to the cycling term Fred .  Now I have never used the cycling term Fred but I've felt such a word should exist.  I have a homemade daggy-looking bike helmet with built in rear view mirror, so  completely independent of the bikes I ride I can be identified as some sort of "other cyclist" or "Fred". Here is the third definition of Fred from the Bis Key Chronicles Blog:

"a Fred is a cyclist who has a ton of cycling gear, especially of the utilitarian “uncool” kind, like mirrors, powerful lights, fenders, bells/horns, heavy leather seats, racks, reflective gear, bags, baskets, etc. The gear and bike may be put together by kludgey homemade solutions, like duct-taped flashlights to the handlebar. This type of Fred is a bike geek who likes/needs lots of gear (even if it is modified stuff not intended for bikes) that a racer would never use, no matter what roadie cyclists or others think. Sacrificing some, or ignoring completely, concerns of speed or traditional roadie/sport cyclist style, these type of Freds are more concerned with practical concerns like comfort, safety, versatility, maintenance, being able to quickly transition to time and culture on/off the bicycle, etc. Freds of this type can be well aware of their fredness, once they are aware of the concept, and often embrace it wholeheartedly."

So - if you are to attempt to try to ride an hpv like mine you will inevitably identified as some sort of "Fred".  So why not cut out the middleman and just call it what it will force you to be. So Fred is the name of my trike type from now on. And one of my aluminium Freds is now for sale on Ebay, here is the link. Start price is $1500.  My timber Fred is also for sale, not on Ebay but details are here.  Price is $3000.

Regards

Steve Nurse


Saturday, January 13, 2018

Around The Bay 2018

Lineup at the start, tea & coffee & biscuits provided.
My trike, second from right

Rick Harker's Cattrike Musahi

On the 12 O'clock Ferry which

most of the riders I saw on the route caught.

A selfie.
Hi

The end of the year came round quite quickly last year, and when I checked the weather for the upcoming Buckley's Ride date (6th of Jan ) it promised to be neither hot, nor horribly wet or windy, so I signed up for the ride, which is a 217k jaunt (ok, tough ride, but moderately flat) around Melbourne's Port Phillip Bay.  Buckley's is Audax Oz's cheap and cheerful ($6 plus food plus ferry fair) version of The Bicycle Network's Around the Bay in a Day ride (Up to $205!)

For a few days prior to the ride I did 2 25k loops of a hilly circuit near to where we live, and I used the wireless speedo on the bike to ensure I kept a steady pace (usually 10k minimum) up the hills.  This training stood me in good stead, and the speedo was useful on the actual ride too.

Saturday, the day before the ride was hot, 41 degrees I think and my wife and I spent most of it inside.  I was fettling the bike and watching television, I checked tyre pressures, bought in supplies of bananas and biscuits and filled the water bottle.

Next morning I was off early and rode to the start at Albert Park.  There were a few familiar faces there from previous years and events like Ian Knoz and Rick Harker.

The ride to Queenscliff went quite well.  There were a wind-protecting bunches to ride in and for most of the way to Geelong did about 27 kph and made the 12 o'clock ferry.  Across the heads in Sorrento I rode with Rick and Ian for a while, but hared off with a fast bunch of Bendigo riders soon after. Haring doesn't do much good though, Ian and Rick caught and overtook me near Frankston.

In the end I was in by 5pm, a good result in my book.  I was happy with the way the trike went.

Regards

Steve Nurse

Monday, January 8, 2018

Disc Wheel Tests Part 2

Problems with Roll Down Tests: Cars parked near the gutter means its hard to mark the stopping position of the bike accurately.

More problems: For accurate results comparing aerodynamic setups (in this case wheels with covered spokes), conditions like tyre pressure, temperature and wind condition all need to be the same between runs.
This is a composite of several screen grabs from this ride with gps post .  It includes the on-screen square popups showing slope and height at different locations.
Hi

For the last few days I've been doing roll down tests on trikes with different style wheels fitted.  The aim was to see which wheels are the more aerodynamic or wind-resistance decreasing.  I'm forced to admit I didn't really come up with worthwhile results in terms of the aerodynamics, but thinking about it and jotting down a few formulas has come up with some methods which might be useful.  So here we go.  I'm going to ask a few questions, see if I can answer them mathematically, then work out if measurements I've made make any sense.

IF I RIDE TO THE TOP OF A HILL AND THEN ROLL DOWN AGAIN WITHOUT PEDALLING, HOW FAST WILL I GO?

The answer depends on lots of factors, but its not hard to work out the fastest speed.

At the top of the hill when the cycle is at rest, the potential energy is MgH where M is the combined weight of cycle and rider, g is the gravitational constant of 9.8 m/(s^2) and H is the height of the hill.  Without pesky wind and rolling resistance, all that potential energy is converted to kinetic energy
 (  (  0.5*M*(V^2))  where V is the velocity at the base of the hill.

We want to end up with V expressed in km/h, and not some other silly units like m/s or miles/h.

First lets simplify the equation MgH = 0.5*M*V^2

to get g*H = 0.5 * V^2

or V(m/s) = (9.8 * 2 * H(m^2/s^2))^0.5

or V(km h/3.6) =  (9.8 * 2 * H(m^2/s^2))^0.5 or

or V(km/h) = ((9.8 *2)^0.5) * 3.6 * H^0.5

or V(km/h) = 15.9 * H(m)^0.5

With my own trials and speedo with maximum speed function, I got up to 54 kph going down the slope shown in the third pic.  Does this make sense?

Well it seems to! The calculated maximum top speed is 15.9 * 29m ^ 0.5 or 85.6 km/h, and I reached 54km/h, so it seems plausible the rest of the speed was lost to air and rolling resistance.

Before adding to this bit of maths, I thought I'd clarify what I'm trying to do here and made the diagram shown below.

Cycle Performance Improvement Map

The whole thing can be labelled Cycle Performance Improvement Map. It doesn't take everything into account, for example adding mudguards will  add weight and may worsen aerodynamic drag but still improve performance.  The tests I'm doing here are seeking some justification for cycle mods in the C5 cell of the diagram, that is showing that improving aerodynamics while increasing weight slightly is sensible.

HOW TO SHOW THAT IMPROVING CYCLE AERODYNAMICS WHILE INCREASING CYCLE WEIGHT STILL IMPROVES CYCLE PERFORMANCE.

The method I propose is to perform an energy balance by quantifying:

A: The energy expended by lifting an aerodynamic cycle accessory up a hill. This is actually the difference in potential energy between "bike plus rider plus accessory"  and "bike plus rider".

This works out at mgH where m is the weight of the accessory, g is acelleration due to gravity and H is the height of the hill.

B: The gain in energy achieved by the accessory giving extra speed during coast-down on the same hill. 

This works out at Mgh where M is the weight of the "bike plus rider plus accessory", h is the difference in height achieved during roll down tests and g is acceleration due to gravity.

To reckon that we have improved things we want an energy gain from the process, that is

mgH < Mgh.  "g" can be taken out to get

mH < Mh.

Now h is the height difference at the end of a downhill run, with and without the accessory installed and is in fact H1 - H2 (H1 with accessory, H2 without).  This is the same as (X1-X2)sin S where X1-X2 (call it X) is the distance apart in metres of the stopping points with and without the accessory and S is the angle in degrees of the slope.  With these new variables plugged in we get

mH < MXsin(S) or

We can divide everything by mH to get an Energy Gain Ratio figure

Energy Gain Ratio = (MXsin(S)) / mH and

For Energy Gain Ratio > 1, the accessory is demonstrably "worth it" in gross energy terms when ascending and descending the hill, but there are some provisos.  For example, your peak energy output of the entire course could be when climbing the hill, and adding to that burden might not be helpful even if there are overall energy gains.

MORE LATER, I WILL TRY TO PROVIDE SOME WORKED THROUGH EXAMPLES NEXT TIME.

Meanwhile here is a link to an article (p16) about a Lightning Recumbent that seems relevant.

Regards

Steve Nurse 

Thursday, January 4, 2018

Disc Wheel Tests Part 1

Standard Wheel Weight 1.22kg

These are part of the wheel covers, I used them to make the "fast trike"

Final Weight of wheels is 1.41 kg, making the whole set of wheel covers weigh about (1.41-1.22)*2kg or 0.38kg

Made from foam mat and gaffer tape, both available from Bunnings, total cost is about $24.

The trike with the 2 sets of wheels, black taped wheels should be more aerodynamic. 

After a roll down test with visible-spoke-wheels. The small stick marks the "first spot", how far I got back up a hill after a controlled" roll down with the exposed spoke wheels.....

and this is the "second spot" result with the covered spoke wheels.

This was photographed from the first spot toward the second spot, distance is about 40m.

Room for Improvement 1, by learning how to operate my wireless speedo properly, I can capture the max. speed.

Room for Improvement 2, by using this gizmo the angle of the road can be calculated and a bit of stuff worked out.
Screen grab from this ride with gps file . Start point is circled right (50m elevation), and approximate stop points are circled at left.

Hi

For better or worse I've signed up to do the (200k or so) Round the Bay in a Day or Audax Buckley's ride on Sunday.  Temps are forecast to go up to 41 on Saturday but return to a more handleable 22 degrees on Sunday.  And I've trained for it a bit, doing about 50 hilly k's on each of Sunday, Monday and Tuesday.  The ride is mostly flat, so an aero bike will help.

So today I've been building some wheels with aero covers for my trike and at the end of the day did some testing. 

The covers are designed to be robust, and whereas previous wheel covers used gaffer tape or camping foam mat, the new designs use both.  Basically I want the design to be reliable and strong first, then light, and looking good comes somewhere down the bottom of the criteria.  I already had all the bits needed including some cut foam.  Cost is $24.00.

Anyway, results were quite good, and I will report more later.