Mix And Match Parts To Build A Better Mountain Bike Derailleur

August 13, 2019 by Lewin Day 4 Comments

Mountain bikers take their sport seriously, and put their bikes through all manner of punishment in the course of a ride. This has given rise to a wide range of specialist equipment, such as suspension, disc brakes and even clutch derailleurs, which help reduce chain slap when riding over rough terrain. However, these specialist derailleurs aren’t available for all applications, so sometimes you’ve gotta hack together your own.

Shimano clutch derailleurs are only really available for 10-speed rear cassettes and up, due to a change in derailleur ratio compared to the earlier 6 to 9 speed cassettes. Using a derailleur designed for 10-speed operation on a rear cassette with fewer gears won’t shift properly.

[SzurkeEg] was inspired by earlier work, and realised that by combining parts from several generations of Shimano hardware, it was possible to build a working clutch derailleur for 6 to 9 speed rear cassettes. The main parallelogram is what handles the positioning of the derailleur, and is sourced from a 9-speed part to get the gear indexes correct.The rest of the parts are sourced from later models with the clutch feature built in.

It’s a smart mechanical hack, and one that isn’t necessarily the most intuitive. But by having a go, and seeing what’s possible, now a whole generation of mountain bikes can tear up the trail like never before. We’ve seen Shimano gear hacked before, too. Video below the break. Continue reading “Mix And Match Parts To Build A Better Mountain Bike Derailleur” →

Reverse Engineering Shimano Bike Electronics

March 26, 2019 by Lewin Day 31 Comments

ANT+ is a wireless protocol specifically designed for use with sensors, and has similar functionality in some respects to Bluetooth Low Energy. It’s found a place among various bicycle equipment manufacturers, to connect smartwatches, cycle computers and electronic gear shifters. Of course, as soon as something becomes a defacto standard someone has to start coloring outside the lines. In this case, Shimano went off book with their DI2 groupset, leaving [kwakeham] with a reverse engineering job on his hands.

[kwakeham] gives us a great example of how to approach reverse engineering. Researching the Shimano hardware by its FCC ID shows that the device communicates using an NRF24AP2 chip, common in ANT+ devices. The Shimano device is then opened, and a logic analyser attached to various test points until the SPI interface between the transceiver and microcontroller is found. At this point, it’s a simple matter of putting the hardware through its paces and capturing data until the protocol can be pulled apart, piece by piece.

The work is documented on Github for anyone wishing to interface with the Shimano DI2 groupset. Reverse engineering is a powerful skill, that can teach you about everything from Pokemon to botnets. Video after the break.

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Bicycle Hub Hydropower

October 11, 2010 by Mike Szczys 36 Comments

[Niklas Roy] wanted to create electricity from moving water so he came up with this hyrdopower generator. It is part of his grand scheme to rent out small personal fountains made from buckets. They need electricity to run so he hooked up the generator to the water jet of a public fountain. It should be possible to use this setup with falling water in a similar way that other generators do.

To build the device he cut fins out of PVC pipe to use as the scoops. They are attached to a Shimano hub generator, meant for producing power while you pedal. The hub is mounted in the front for from a bicycle, which can then be mounted anywhere moving water is available. The only thing that worries us about the setup is [Niklas’] comment that being showered with water didn’t destroy the hub right away.

See the hub and the smaller fountains in the clip after the break.

Continue reading “Bicycle Hub Hydropower” →