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Efficiency and Electrics

Despite the bike being a very old innovation it is still one of the most efficient transport vehicles known to man. Even a simple steel bike with one gear can propel a person at about 4 times walking pace whilst using just half the energy, making it 8 times more efficient than walking. The only downside is during a hill climb where a walker will only have to lift their own weight up the hill whereas a bike rider will need to move the bike as well. However, this is more than compensated for on the downhill where energy is returned to the freewheeling cyclist and even on the flat a bike will coast between pedal strokes with great ease.

The hill climb challenging aspect of a bike has been the source of much innovation over the years. Gears can be used to allow a rider to trade speed for extra torque during an ascent; and of course bike weight plays a part. It is for this reason …keep reading

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Recently there has been talk of adding an anti-lock brake system (ABS) to bicycles. This is an exciting development and so we thought it relevant to look at how these systems work and what benefits they may have for the rider.

There has been interest in reducing wheel slip from …keep reading

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Build your own Box Bike.

So you want to build your own box bike?
At Rodford we applaud innovation, those creative “men in sheds” and we like to support people who wish to do their own thing. So here’s a few things to consider when designing your own box bike. Some information to help you avoid some of the common pitfalls.

Main chassis.
Box bikes are usually either single spar or twin spar.
The single spar is the simplest build but overly long bikes of this type can waggle. Side rails or front and rear deck hoops can help reduce this.
If you want to create a very long load area then consider a twin spar design. This also has the advantage that front wheel can be tucked into the frame, creating better use of the wheel base length.
Which ever design you choose, …keep reading

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Be safe, Be seen. Fluorescence and reflectance

When cycling the dark winter commute, being seen is half the battle in staying safe.
To be seen as the light fades, you need both Fluorescent and Reflective surfaces on your bike / clothing.
Here is a short analysis on how these materials work to help when selecting clothing or accessories for increased visibility.

Reflectance is the most easily understood of the two parameters.

The reflector was invented by  Mr. Arvi Lehti, a farmer in Finland. He invented it to make his livestock more visible at night.
Inside a typical reflector there are two systems used. One uses spherical beads which is particularly good on flexible surfaces. Rigid structures can use prisms instead.
Bicycle reflectors work ..keep reading

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Mention a tyre and most people will visualise a rubber band around a wheel to soften the ride and provide grip, but this seemingly simple device is actually quite complex. The complexity raises questions about which is the right tyre for a particular purpose and how you should choose a tyre for a particular vehicle.
Without going into extreme depths, it is worth having a general look at some of the important characteristics of tyres and to observe a cross section of vehicles to understand which properties are most significant in a given situation.
Let’s look at efficiency, control, surfaces, pressures and tread.

Efficiency of a wheel in motion, …keep reading

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Speaking of Spokes……

Perhaps you are wondering about the mechanics behind the bicycle wheel, how spokes work, what lacing patterns can be used and so forth. More likely, perhaps your not. Regardless, here are a few words on the fascinating topic of spokes.

The spoked wheel was first conceived by Mr George Cayley who was an early pioneer of flight. As well as being successful in producing a working glider, he invented the wire spoked wheel in his quest to design a light and durable wheel for his flying contraptions. Spoked wheels were around much earlier than this, chariots and horse drawn carts had spoked wheels, but these wooden masterpieces were not stressed like the wire spoked wheel. On the wooden wheels the weight of the vehicle was simply supported by whichever spoke was at the bottom. The spokes had to be strong enough to support the weight of the vehicle plus its load and with excess strength to resist impacts.
Wire wheels came later and were significantly more advanced …keep reading

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Buckle up and knuckle down

In order to reduce the weight of a bike it is important to explore tube dimensions such as wall thickness/diameter ratios and length/diameter ratios to determine the best dimensions for the purpose. Looking into this can lead to a somewhat interesting (for some at least) foray into stress analysis and buckling theory.

Referring to a previous blog on second moments of area, we know that shape of a part greatly affects its mechanical properties and this explains the reason for most engineering shapes used, from simple “I” beams to complex aluminium extrusions. In the world of cycling, round tube is often favoured for it’s consistent stiffness and strength in all axis and its traditional cosmetic appearance; but what should the wall thickness and diameter of the tube be for the best performance?

In an attempt to answer this we …keep reading

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Lefty loosey, righty tighty (but not always)

Every so often someone enters the workshop wanting help removing or replacing a bottom bracket. These assemblies take all the energy from the cyclist’s legs and turn it into rotational force to drive the wheels. They are also low down in the bike frame (apart when used on recumbents) and so they suffer from debris and water thrown up by the front wheel.

Consequently the bottom brackets are always secured tightly and combined with the environment they can be hard to remove; it can be difficult to tell if you are turning them the right way to loosen them.
So here are a few words on the subject of pedal and bottom bracket threads and an explanation on why they are orientated the way they are.

First some terminology. …keep reading

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Balancing Bikes

It is a surprising fact that even though the bike is 200 years old this year (2017), it is still difficult to explain exactly how it works. It is a case that we know what works and what doesn’t and how to build a really good bike; but not really why.
However one thing is for sure, learning to ride a bike is tricky but once mastered it seems you can ride any single track vehicle after a moment’s practice.

So what exactly is going on when you balance a bike?

It is a fact that steering the bike provides two functions. Firstly it helps you travel in a chosen direction but secondly …keep reading

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Looking at Moments for a Moment

We’ve recently been investigating the benefits of different steel sections for our frame parts. Rectangular and square box section are easy to come by and have flat faces which can simplify assembly. The question is – would they be any more or less rigid?

To answer this we modelled some comparative parts on a CAD system, whilst not a definitive answer it did produce some results of interest.

Stiffness or Rigidity
For some sections the best orientation to maximise stiffness is obvious just from looking at its shape. In the example below the same part can be expected to be stiffer in …keep reading