11-speed gearsticks: Trend or dead end?
The gearbox on a bicycle is actually an absurdity. Filigree gear wheels, packed close together and with too few teeth by mechanical engineering standards, are subjected to murderous chain forces. And without any protection from the harsh biking environment. Mud, clay, sand, dust - everything that gets under the wheels also gets onto the chain; the dirt is almost magically attracted to the lubricant, without which no chain runs smoothly. Wherever metal meets metal and dirt grinds in between, material is removed. Even the hardest steel, not to mention the much softer aluminium, erodes between the pins and plates of the unsealed chains and on the flanks of the sprockets and plates. Only by replacing worn components in good time, especially the chain, will the drive remain reliable.
More sprockets = more wear?!
Wear follows a simple logic: the higher the forces and the smaller the contact surfaces, the higher the wear. If more sprockets have to fit into the same installation space, it is reasonable to assume that the contact surfaces inevitably become smaller and the wear pressure increases. So are 11-speed drivetrains only for high earners who don't care about the cost per kilometre when cycling?
Sram counters this and promises a four times longer service life than before for its XX1 11-speed chain. The reason for this is said to be a special coating and hardening. Shimano is also advertising a new, friction-reducing coating for the XTR chain. Marketing magic or technical progress? In order to test the wear under controlled conditions, our sister magazine BIKE subjected three 1x11 drivetrains to a rigorous test on the chain test bench:
Each transmission was subjected to a 45-hour endurance run on the chain test bench (equivalent to around 750 kilometres). Fine quartz sand and water were applied to the lubricated chain three times during the test to accelerate wear. With a tensioning force of 100 kilograms of weight, we subjected a frequently ridden, medium gear ratio of 32/17-19 to a "cadence" of 75 revolutions per minute. Metallic crunching and grinding acoustically signalled the destructive forces during the ride. The elongation of the chain was recorded several times and the sprockets and blades were checked after the test under load with a new chain. Tooth wear was also measured.
Conclusion on the test of the 11-speed drivetrains:
The manufacturers have done a good job and designed the 11-speed components to be quite robust. The durability is on a par with the ten-speed drivetrains. However, steel would be desirable as a gear material for the front of the single cassette. This would significantly extend the replacement intervals.
The complete article was published in Trekkingbike issue 1/2016. You can read the entire issue in the Trekkingbike app (iTunes and Google Play) or order the issue in the DK shop.
You can download the individual articles as PDF files here.
