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 a road racing rider will prefer a lightweight bike for quick acceleration and the minimum deficit in a hill climb, but not all bikes are designed like this. Downhill mountain bikes can be heavy because they need to be very robust and have suspension, good brakes and bulky tyres, however these bikes are not so much fun up a gradient where the suspension soaks up rider input and the weight works against the rider.

So clearly frame or bike weight is important to get the most from a bicycle’s power source. Consequently the quest for a good hill climbing bike has driven frame builders towards ever lighter materials. Original “hobby-horse” type bicycles from the 1800’s were largely made from wood, making them quite heavy but still faster and more efficient than walking.

Dandy Horse style Bicycle.                                      Photo by Gun Powder Ma

For many years steel has been used for bike frames and lightweight thin walled tubes have been developed by companies such as Reynolds specifically for frame builders. Tubes no longer have to be round and they are often double butted meaning they are thicker walled at the ends and thin in the middle to match the stress concentrations of their application.

Simple cross-section sketch of a double butted tube

Nowadays Aluminium is popular for it’s lighter weight, but careful design is needed to avoid fatigue without adding too much weight back in. Titanium is another hi-tech, light, strong and corrosion resistant material and of course carbon fibre frames developed from race bikes now lead the way.

A modern carbon bike is a marvel of engineering design. A racing frame might only weigh 700grams and a whole bike less than 7kgs if lightweight componentry is used. This has a huge benefit during a hill climb where bike weight becomes important.

But what about bicycles for transport?
Weight is still a consideration here, but not an all out goal like in the world of racing. The more cargo you add to a bike the less significant the frame weight becomes. Add more than 10 or 12kgs of cargo to any bike and you will be more concerned about frame strength, handling and braking than the weight of the frame. However, when selecting a cargo bike frame weight remains a parameter that most riders will consider and excessive weight is certainly to be avoided.

So what is the answer to hill climbing with cargo? Clearly even the fittest rider on the lightest bike will struggle if the hill is steep, long and the cargo heavy.

But………….There is now a new technology to help with hill climbing. Something that actually adds to bike weight but something that enables even a rider of modest fitness to climb hills.
Electric Assist.
Electric motors have been around for hundreds of years, but battery technology has always limited their mobile applications. However Laptop and mobile phone development has improved the situation and this technology has now reached the transport world. New Lithium based batteries have an impressive output, longevity and low weight. This means adding an electric motor to a bicycle has more benefits in terms of performance than the deficit of carrying the battery and motor around.

It is important to make a distinction here between the pure simplicity of a simple pedal bicycle and the benefits of an E-assisted vehicle. The bicycle will always be popular and so it should be. A fantastically simple, yet efficient machine which has mobilised both the developing and modern world. It’s a great thing. It is also true that if you cycle for a fitness challenge or in any kind of competitive way then assisted bikes may not appeal.
However E-assisted bicycles also have a place. They should not be scoffed at by the recreational fitness rider because they can move stuff, cargo or kids, in the hilliest cities where a simple bike and average rider would struggle.

Summary.
If you live in a town with hills* an E-assist equipped bike can help take the strain out of the climbs. More and more people are starting to consider E-bikes as a possible mode of transport and it has many benefits. Even on a solo bike it can help you reach your destination quicker and in less of a fluster. It is possible to cycle in a uniform or smart suit, without needing a shower when you arrive. Add the aspect of cargo into the picture and the E-assist is a game changer. Bike weight is no longer the critical factor like it is with a simple pedal powered machine and an E-assisted box bike is a capable cargo hauler.

So there we have it.
Even on the most efficient of bikes, with a light frame and a fit rider there is no escaping the fact that when you add kilograms of cargo, the bike becomes hard work on the hills. An E-assisted box bike is one countermeasure to this situation. A well designed box bike is more of a vehicle than a bike. It has a greater presence on the road, the ability to move with the traffic flow and to climb hills without exhausting the rider. These vehicles are ideal for inner city deliveries, couriering or the school run.

At Rodford many of our bikes are fitted with crank drive motors to overcome the strain of hill climbing and to allow riders of all abilities to benefit from the freedom and enjoyment of cycling for transport. If you live in one of Britain’s hilly cities (or even if you don’t) then please call us for a test ride.

By the way – where are Britain’s Hilliest cities?

Bangor
Bath
Bradford
Bristol
Durham
Edinburgh
Glasgow
Lancaster
Leeds
Lincoln
Liverpool
Norwich
Sheffield
St Albans
Stirling

Cities marked in Bold are particularly hilly.

Vale Street in Bristol. One of Britain’s steepest streets. Suitable E-bike territory?

*Not all towns are hilly, but most settlements have evolved around rivers; this stems from old civilisations when being near water was necessary for life. Rivers (not surprisingly) run down hill and therefore lie in valley’s, meaning many town and city centres are effectively surrounded by hills and most roads climb upwards as you leave the centre.