To calculate the Aerodynamic drag on our design and show how the wind flows around a DryCycle whilst it is in motion, with the wheels turning on a virtual road, we contacted TotalSim Ltd based in Northamptonshire, England.
TotalSim Ltd have a large team of experts in Computational Fluid Dynamics, who have worked on a wide range of vehicles from bicycles and motorbikes through to race cars, and even yachts and other marine applications, though of course their work with bicycles and cars was most of interest to us. They ran our model through their CFD simulation computer systems and calculated the Coefficient of Drag (CD) ratio of our vehicle to be 0.37, which is comparable to cars, and is considerably lower than the 0.6 CD of a racing cyclist in lycra on a racing bicycle, or the 0.8 CD of a commuter type cyclist in a relaxed position on a normal bicycle.
During the design process we've conducted numerous Finite Element Analyses (FEA) through our engineering computer software (Autodesk Inventor) to make sure that our DryCycles would perform well in the real world with a good margin for error. For example the rollover bar FEA that you see below shows that the rollover bar will hold 3 times the combined weight of both the DryCycle and it's 120kg payload when the DryCycle is inverted.
Some of the more specific design choices we took in regards to safety that we haven't already covered on the Crash and Security section of this website include:
The MM bend. On the sidebars the last portion of the sidebar is bent in by a few degrees before joining to the rollover hoop at the back of the vehicle. This bend helps with aerodynamics, but also significantly increases the strength of the sidebars in resisting sideways forces that are put against them in a side impact of the vehicle. There are several other bends in the vehicle that have been designed with similar purposes in mind, including the bumpers, which instead of being simple straight pieces of metal are curved outwards to greatly increase the forces they can withstand in crashes.
Crush cans. The drilled out sections at the front and rear of the DryCycle directly behind the bumpers are designed to deform in front and rear impacts, and in doing so they absorb some of the force of the impact.
The double V front suspension struts. The need to accommodate the riders feet whilst still having a working suspension and steering system at the front of the DryCycle meant coming up with a new solution. Our double V suspension strut design gives plenty of space for the riders feet to rotate on the pedals whilst still giving the strength needed to properly support the front wheels.
Round tube roll cage. The roll cage surrounding the rider in the DryCycle is made from round tubing for several reasons: It vastly reduces the possibility of sharp edges surrounding the rider in the event of an accident compared to square or rectangular tubing, it collapses progressively in an accident, and due to the second moment of inertia directing the impact around the edges of the tubing it offers better strength, pound for pound, in a direct impact, than square or rectangular tubing. There are several good reasons why rollover cages on race cars almost always use round tubing.
The Rectangular tubing is used in the Chassis for other similarly good reasons. Firstly, rectangular tubing reduces flex, stiffening the chassis over what would be possible with the same weight of round tube aluminium in the same configuration. We also use a stiffer grade of aluminium in the chassis, 6082T6 as opposed to the 6063T6, which is what is needed for the round tubing in order to allow it to bend to our roll cage design, this stiffens up the chassis even more. For best road handling a stiff chassis is desired, but for good crash protection a somewhat pliable structure absorbs the impact rather than immediately imparting it to the rider as an overly stiff structure would.
High Grade, Tempered, Aluminium Framework
This is the DryCycle's framework, it's made out of 6082T6 and 6063T6 grade aluminium. Both of these are high grades of aluminium more commonly found in aircraft and up to 3 times more rigid than common lower grades of Aluminium.
Here's just a few design choices we've made to make life easier for you whilst still injecting style into your ride:
'Side air inlets', designed to add a sporting touch to your DryCycle these 'air inlets' are actually holes that you can put a chain through to lock the DryCycle body and framework securely to a fixed bicycle stand or similar. This is a high wear location due to it's use, so the grey lining is designed so that it protects the bodywork of your DryCycle whilst you repeatedly lock it up with a chain. When this grey 'air inlet' panel becomes worn after a lot of use you can just replace it without needing to replace the body panel.
Separate Wheel linings. These don't just give a more robust 'off roader' style look around the wheels they're also functional. This is another high wearing location as naturally the wheel arches will experience a lot of road debris around the wheels, so these wheel arches that are held in place with automotive style clips can be replaced when needed without replacing body panels.
Two access panels in the front undertray. These allow easy access for maintenance to parts at the front of the DryCycle, as well as giving another option for additional ventilation if ever you want it.
Recessed front lights to reduce light spillage within the cabin. In our early designs the light spillage from the headlights was reflecting back into the vehicle and onto the canopy at night, which was distracting. Our stylish quad headlight arrangement significantly reduces this light spillage without completely removing it, so that the reflected light now acts as foot well lighting.
It's not all about serious dependability and safety though, getting the ride just right was fundamental as well. After getting our chassis to be suitably stiff we then needed to add in the suspension. We tried many different types of suspension, including simple springs and air suspension, but after much deliberation we decided that the optimum ride on a DryCycle was delivered by spring units with inbuilt adjustable oil dampeners. We then tested several different springs before picking the spring rate to suit our weight of vehicle to achieve the most compliant and predictable ride.
Through years of development we've made a vehicle that handles well, despite it's very short wheelbase and seemingly tall stance compared to it's width. The linked rear suspension adds stability through the corners, as does our obsession with keeping the weight low in the vehicle, whilst the Ackerman geometry and rear differential remove scrub through the wheels whilst cornering. The narrow tyres reduce rolling resistance and give just the right level of grip for predictable handling and the strong hydraulic brakes on all four wheels give great stopping power.
Of course the only way you're going to find out just how well we did this is to come and try one for yourself so go ahead and treat yourself to a test ride.