Search the Community
Showing results for tags '3 speed conversion'.
Found 1 result
I have been working on a 3-Speed Conversion with alienmeatsack, biknut and steve-condie . I have 2 yellow bikes purchased on the third day of the first indigogo campaign, one for myself and one for my lady. I have purchased most of the needed parts. Three speed freewheel cog set, the derailleur and a new 52t sprocket crankset. The only part missing, besides a chain and some misc. hardware, is a shifter. Due to the odd pitch (pitch is the measurement between cogs) of the 3 speed cogset (6.2mm vrs. 5mm-5.5mm found on most 6-10 speed bike cassettes) I am unable to find a suitable index shifter that will work with a shimano derailleur. Apparently, no one makes an index shifter for a 3 speed, only a friction shifter or a twist grip shifter. I would really like to use an index shifter with a gear indicator. Not so much for myself, but to simplify shifting for my ladies bike. She likes things obvious and simple. Myself, I would use whatever I could cludge together, if I had too. With only three speeds it just strikes me that you should just be able to thumb the shift lever and shift up or down with the indicator showing 1, 2 or 3. Yeah, right!! We all know what should be and what is are often miles apart. No one makes a 3 speed rear derailleur shifter, they only make 3 speed front derailleur shifters and the two are entirely different animals with different pull lengths (the length of cable pull required to move the chain to the next cog). To solve my problem I have decided to investigate building an electronic derailleur controlled by an up-down shift switch. Now this might seem like a complicated solution to the shifter problem but being a mechanical engineer (in a former life) I decided to investigate the possibility. Shimano and Sram both make electronic shifters but at a cost of close to $2,000 for the set, I decided to see what good old DIY ingenuity could accomplish. Never dismiss the capabilities of a broke man with an expensive dream. Necessity truely is the mother of invention. Besides, it sounded like a fun project and being retired, I'm supposed to have time for fun projects, right? So, I did what any modern inventor would do, I went to Google for information regarding electronic derailleurs. To my delight, I found quite a bit of information on the subject. It seems that when shimano came out with their $2000 electronic shifter/derailleur setup, for road bikes, it set off a storm of shifter envy among the poor but inventive DIY community. The best website, devoted to the subject of servo shifted derailleurs, was DIYshift.com by Preston Fall (a fellow Oregonian). This site is referred to in almost all of the web articles that I came across. Unfortunately, the site is no longer available having been replaced by what ap[pears to be an Asian porno site. What makes this so unfortunate is the fact that most of the newer articles used DIYshift.com as a model for their designs and they refer to that site for pictures and details leaving little, useful, detailed information, just vague descriptions of the actual mechanism. Also, there are half a dozen uTube videos about DIY shifter projects. As is usual with uTube videos, there is a noticeable lack of hard information about how to build one with builders showing very little detail and few closeups, preferring to tease you with their cleverness and leaving you to fend for yourself figuring out the details. The good news is I found the contents of DIyshift.com on Github https://github.com/Diyshift (thank you Google) Here is a list of all of the uTube videos devoted to electronic shifters. https://www.youtube.com/results?search_query=DIY+electronic+derailleur This is worth checking out so you can see what the possabilities are. I also found an instructable detailing how to build an electronic derailleur. http://www.instructables.com/id/DIY-Electronic-Derailleur/ This project is totally awesome. Not only does it solve the shifter problem but it can easily be upgraded to a larger cassette by changing the programming. Also, I have some ideas to turn this into an auto shift by putting a strain gauge on the crank chain that will automatically upshift or down shift depending on how much force I am putting into peddling. Much better than the cadence system built into the controller. It would be easy to also put together a shifter that would also shift a front derailleur by using a 2 channel servo controller. Do to the cheap cost of servo controller boards, DC-DC converters and arduino processor boards, this project could be put together for about $50 plus the cost of the derailleur. The whole system could be powered by the bike battery or a separate 7.4v Li-On battery, like the kind used in RC models. According to what I've read, a 7.4v battery is good for about 40,000 shifts (a conservative estimate). I plan on putting some real effort into this project, including designing a circuit board, shift switch with an led readout showing the gear selected and the servo mount. The software has already been written but I will check it out and make sure that it works with my version and is easy to use. I have an idea that will allow me to program the controller wirelessly using my tablet or a smart phone making it easy to tune the system. I think I will see about putting together a complete shift kit with everything but the servo and the derailleur. I have quite a bit of work to do on this but I will post more information as it comes. I am shopping up parts right now and still waiting for my shimano 105 derailleur to arrive. I'll know more when it gets here. Let me know if anyone out there that has any experience with one of these electronic shifters or if there is anyone else interested in this project.