If you just want to get building move on to step 1.
Background
This instructable is part of a larger project to build the ultimate bicycle computer, which you can read about on my blog. It will show you how to build an electronic rear derailleur for Shimano parts. I've tested it on the RD-4500 Shimano Tiagra, but this method should work with similar derailleurs. Rather than pulling the shift levers, you press a button to get to another gear.
Motivation
1. Once both derailleurs are electronic you get automatic trimming, which means no more chain rub!
2. Easier/smoother shifts. OK so it's not super hard to change gears with mechanical levers, but going electronic means you get an accurate shift every time.
3. Cheaper than the commercial alternatives. Like thousands of dollars cheaper...
4. When your gear changes are combined with other metrics like your heart rate, gps, speed and incline you can improve your ride by finding your weakness. Were you on the correct gear on that incline?
5. It's a conversation starter.
6. Adding electronics to anything is always cool!
Skills Required
- Basic soldering and electronic skills. See Sparkfun's Soldering 101
- Very basic Arduino knowledge like how to upload a program. See Sparkfun's beginning embedded electronics
- Basic bike mechanic skills like a removing derailleur, if you do your own bike maintenance you be should OK
Progress
So far we've got the rear derailleur shifting and plan to do the front so look for future instructables for updates and new features. At the time of writing the software does not turn off the servo to conserve battery power because there is a chance of gear slippage. This means you will have limited ride time. A fix for this coming soon so follow my instructables account.
Open Source
Up to date Arduino sketch, schematics, Fritzing diagram, bill of materials and CAD diagrams can be found on the project page http://nabilt.github.com/diy_eshift/.
Future plans
- EEPROM wear levelling
- Waterproofing and better a enclosure
- Better cable management
- Machined servo bracket
Background
This instructable is part of a larger project to build the ultimate bicycle computer, which you can read about on my blog. It will show you how to build an electronic rear derailleur for Shimano parts. I've tested it on the RD-4500 Shimano Tiagra, but this method should work with similar derailleurs. Rather than pulling the shift levers, you press a button to get to another gear.
Motivation
1. Once both derailleurs are electronic you get automatic trimming, which means no more chain rub!
2. Easier/smoother shifts. OK so it's not super hard to change gears with mechanical levers, but going electronic means you get an accurate shift every time.
3. Cheaper than the commercial alternatives. Like thousands of dollars cheaper...
4. When your gear changes are combined with other metrics like your heart rate, gps, speed and incline you can improve your ride by finding your weakness. Were you on the correct gear on that incline?
5. It's a conversation starter.
6. Adding electronics to anything is always cool!
Skills Required
- Basic soldering and electronic skills. See Sparkfun's Soldering 101
- Very basic Arduino knowledge like how to upload a program. See Sparkfun's beginning embedded electronics
- Basic bike mechanic skills like a removing derailleur, if you do your own bike maintenance you be should OK
Progress
So far we've got the rear derailleur shifting and plan to do the front so look for future instructables for updates and new features. At the time of writing the software does not turn off the servo to conserve battery power because there is a chance of gear slippage. This means you will have limited ride time. A fix for this coming soon so follow my instructables account.
Open Source
Up to date Arduino sketch, schematics, Fritzing diagram, bill of materials and CAD diagrams can be found on the project page http://nabilt.github.com/diy_eshift/.
Future plans
- EEPROM wear levelling
- Waterproofing and better a enclosure
- Better cable management
- Machined servo bracket
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Wire cutter
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for the help,to make this very interesting project.
It's exactly what I was looking for.
do you have in mind for the front derallier?
i would like to see a video with this working.
can you fine tune without pc just in case it happens somethin on your ride?
great!!!!if you add the front derallier i will built it the same time!!
Here's an idea for when you get the front der added to the mix:
Since you are using an arduino, how hard would it be to program in a gear sequence so when you hit the upshift or downshift buttons it progresses to the next gear in a logical sequence, moving either or both the front and rear ders?
Also, since my ride is a home built trike with a mid-drive, I have 1 front on a triple, a 6 cog mid, and a 7 cog final. Could this be programmed to account for all three?
I would definitely be interested in building something like this!
Thanks for the 'ible!
Shifting in sequence is very doable but I question its usefulness on the road at least for the way most bikes are geared and the way I ride.
First, although, mathematically, there may be 21 gears, there are usually duplicates. You would not want to waste time shifting to a gear that is marginally different. Ok, you need to (and can in fact) program the arduino to bypass one or the other.
Secondly, when I shift I usually change only one derailleur. To clarify, say I have a triple chain ring. On the ride, I find a sweet spot using the middle ring. UpHill coming - I switch to the smaller front or a larger rear but not both on one shift. Don't need to - one or the other improves my situation and usually close enough. If not close enough, I tweak (probably with the derailleur I did not change initially). Chances are my changes are not sequential at all.
So maybe a programmed set of "my favs" gears would be more useful whether accessed sequentially or directly.
If we really were to put in the bells and whistles, Version 17.1 would chose the gear for you based on your cadence, heart rate, the incline, your power output and your fitness level and length of ride. It also stores your ride history and uses predictive logic to determine the gear and when it will shift.
But I am happy with the promise you've shown so far! Good job. Very inventive.
Not difficult at all. A few people have requested this so I'll add it to the feature list. The only difficulty is making installation easy with all of these new configurations.
> Could this be programmed to account for all three?
Definitely. The next version has an LCD so each user could choose their configuration on the screen.
Thanks!
I can tell you the front derailleur is much easier to control with a servo than the rear. I have been working on a similar project for some time http://www.diyshift.com . Have you had any problems with derailleur ghost- shifting over large bumps? That was one nut that I was having difficulty cracking without leaving the servo powered up and eating batteries.
I look forward to seeing your updates and test results.
I think this is great and should provide endless funin the dark winter nights when riding is impossible...
well done to all!
> Have you had any problems with derailleur ghost- shifting over large bumps?
I have. I'm thinking of adding some tension or a normally closed brake to hold the derailleur in place to fix this.
Maybe we should chat and see if we can help each other out. Email me at nabil dot tewolde gmail.com.
Referring to the schematic, could you please explain futher the use of the transistor to switch the servo power? I've only seen this done with the base being used to control the load. Thanks.
for example I want to shift into Gear 5 and hold that ?
For an anti-theft system:
I try to get a new derailleur and use the old one for this project. and what servo size are you using?
Maybe, but I wouldn't recommend it. They tend to have less torque compared to an equivalent size servo. They are generally used when you need high accuracy.
> and what servo size are you using?
I am using the medium size HiTEC HS-225MG Servo.
I also thought of using a worm gear from a guitar machine head and then send the arduino to sleep to save battery consumption.
Anyway keep up the good work.
Super cool project!
http://www.google.com/products/catalog?hl=en&q=bike+dynamo&um=1&ie=UTF-8&tbm=shop&cid=3052823855019776153&sa=X&ei=btHQT6LqA4f69QTKj6G_AQ&ved=0CKkBEPMCMAc
Good work.
I am just getting into the Arduino myself (still haven't gotten it in the mail, I ordered it last week lol) & I can't wait to get into the work w/ it & start programing & posting projects for people to use.
All things considered this is a wonderful project & I can't wait to try it out myself.