Chain Lubricant Testing
Have you ever wondered the effect that your choice of lubricant has on your chain’s efficiency? On our chain rig here at Silverstone Sports Engineering Hub we recently put a variety of chain lubricants to the test to find out.
The chain rig uses simple harmonic motion to quantify the overall efficiency of a chain-chainring system. It uses a swinging pendulum in order to articulate the links of the chain around a chainring. The pendulum rotates on knife edge bearings instead of a traditional rotational bearing, in order to eliminate frictional losses and damping in the system. Tension is applied to the chain in order to simulate a rider applying power to the drivetrain, this tension can be changed depending on the desired power output. The swing of the pendulum over time is monitored with a non-contact rotary sensor in order to not add further damping to the system.
After releasing the pendulum from the starting angle, the pendulum experiences damping due to frictional losses of the chain. When the angle of the chain is plotted against time the reduction of each peak can be used to calculate its percentage efficiency. The pendulum can be released and swung without a chain in order to compare the chainless decay to the decay when a chain is fitted. In the time interval that it takes the pendulum to decay when a chain is fitted, the chainless configuration will see negligible decay and thus 100% efficiency. Therefore, during the testing, the damping of the pendulum swing is related directly to the friction of the chain, i.e. the frictional and drag losses of the pendulum and the knife edge bearings are negligible.
The rig requires testing of multiple samples in order to obtain efficiencies of various chains on our rig and enable comparison between the different lubrication methods.
For the purpose of this investigation, 4 lubricants and a degreased chain were tested. The chain was stripped with white spirit following each test, then dried thoroughly using an air compressor prior to being re-lubricated with a different lubricant. This was done by laying the chain flat on a workbench, and applying a drop of lubricant to each roller. The chain was allowed to sit for 5 minutes to absorb the lubricant, then another drop was placed on each roller. Once the lubricant had absorbed into the chain for a further 5 minutes, the chain was installed on the rig.
Chain tensions of 200, 300 and 400N were used, with 3 repeats of each. These corresponded to approximate powers of 200-400W at 90rpm. Application of the lubricant on the chain can somewhat be variable and subjective, therefore, each chain was also rotated to test two chain positions. These two positions were then averaged to give a representation of the chain as a whole.
The average efficiencies for each chain and tension, as well as their respective standard deviations are shown in the tables 1-5. These efficiencies are plotted in the bar chart shown above.
Lubricant 3 had the highest average efficiency across all the chain tensions, closely followed by Lubricant 1, and then lubricant 4. A decrease in chain efficiency can be clearly noted with increasing chain tension. However, the standard deviation of the efficiencies can also be seen with increasing chain tension.
Across all of the tensions, lubricant 3 was the best performer with the highest average efficiency of 93.55%. Interestingly the degreased chain wasn’t that far behind, with an average efficiency of 92.85%.
Whilst no one lubricant was a top performer across all of the tensions, there were clear trends in which conditions lubricants performed best. As stated, lubricant 3 performed the best on average across all tensions. However, the highest efficiency seen overall was that of lubricant 1 at 200N.
For correct interpretation of the results, it is important to remember the purpose of a lubricant. Which in the case of a bicycle chain, is to reduce friction in the chain, whilst also reducing wear on the internal components of the chain, which ultimately contribute to the stretching of the chain over time. The above test method serves as quantification of the friction in the chain, with no regard for wear reduction and longevity of the chain. Consequently, although at face value the degreased chain appears to rank 4th, a degreased chain will experienced increased wear, despite there being lower friction. Therefore, the most efficient lubricant across all operating conditions would be would be lubricant 3.
Although this method enables accurate investigation of the efficiency of a chain, it tests this in isolation. For example, a chain efficiency of 95% using this method cannot be taken as a ‘whole drivetrain’ efficiency and used for further modelling. However as the results demonstrate, clear differences in chain efficiency can be seen, enabling direct comparison between lubricants.
If you would be interested in arranging a booking for the Chain Efficiency Rig to optimise your own equipment choices, please refer to the Cycling Test Lab section of our website for further information – https://silverstonesportshub.co.uk/cyclingtestlab/