Auto Gear Bicycle

[sakyasri]

Hey guys im not very sure where this thread belongs but i'll post it here..
Me and some of my friends are designing a circuit to make bicycles autogeared. We are planning on doing this by using an opto encorder to get the frequency/voltage (not sure which one yet) of the front wheel and then to transfer that to a PIC 16F88. and then the PIC has to send some signals to a stepper motor to move the gear cable by a certain amount.

Since we are demonstrating with a model we have to find out the maximum frequency of the wheel and break that into 7 equal parts and then depending on that to set the motor to 7 different levels.
For now we have a L298N also along with the PIC and a 6 wire stepper motor....
we dont have any schematics or codings to begin with... and cant seem to find any either...

If anyone can help with this it would be a great help

 

[KeepItSimpleStupid]

I think you also have a glitch to deal with: The derailer only operates when your pedaling?

 

[birdman0_o]

Before you go on, how exactly is a bicycle gear system going to work? How are you going to measure torque? If it is just a flat surface then this wouldn't be an issue I guess, not sure about the geography of your area.

 

[SABorn]

Search the forum, as this topic was covered a month or 3 back, when someone else done this very project.

Or are you the same person trying to ask the same question.

There is several problems you will encounter that was covered previous.

Pete.

 

[sakyasri]

thankx guys for the quick responses.

@KeepItSimpleStupid
yes the derailer does move only wen pedalling bt we are plannin on gettin the speed at the wheels. so whether it is movin or not is not an issue according to our system as long as the wheels r turning.

@birdman
im sorry i cudnt get your question..... we are not measuring torque anywhere. jst the stepper motor has to be able to handle a high torque to turn the gear cable.

@SAborn
I searched for it in but i cant find anything related to this..... do you remember the name of the thread or something like tht which could help with the searching. if it is already discussed it would be very easy.....

again thankx everyone

 

[sakyasri]

hey thankx for the quick responses..

@KeepItSimpleStupid
the derailer does work only when pedalling but tht wont hav an effect on our system as we are tryin to get the speed at the front or the back wheel.. not having anything to do with the derailer..

@birdman
im sorry i couldn't get ur question... why would be hav to measure torque..? we just need a stepper motor good enough to pull the gear cable.. i mean no need of measuring torque...... rit?

@SABorn
I tried but i couldn't find any posts related to this..... if you dont mind could you tel me some keywords to check for it...? If it is already done this would be a whole lot easier....

thankx again guys

 

[gary350]

This has already been done. Serious bikers are into extremely light weight bikes they don't want an auto shifter it adds extra weight to the bike.

Use an RPM indicator on the pedals to make the gears shift at the correct RPM. Most serious cyclist pedal at about 80 to 120 RPMs. I like to pedal at 85 RPMs maximum on a serious 40 mile ride but if I am taking an easy bike ride I like to pedal much slower about 60 RMs. You need to find a way for each person to dial in their prefered pedal RPM the gears will shift at on a flat level road with no head wind. Up or down hills it will still work fine because as the bike becomes harder to pedal up a hill it slows down and the bike will down shift at a preset lower RPM.

 

[birdman0_o]

As a bike enthusiast I really feel as if this is something that shouldn't be automated. But Gary is correct, the RPM is enough to change gears but there will be tons of different glitches in different scenarios.

 

[KeepItSimpleStupid]

There was a CC article where a guy made an ABS for a mountain bike which I thought was really cool.

 

[gary350]

The only thing your auto gear can not do is inticipate when to shift before it needs to shift. When you approach a steep UP hill you need to shift to a lower gear on the front sprickets before you start up they will NOT shift under load. Once you start up the hill it is too late to shift because the front derailleur will NOT shift under load. You need a radar or laser scanner to detect the hill about 50 ft before you start up.

You can probably do auto shift only on the back derailleur and leave the front derailleur as manual.

 

[sakyasri]

hey im sorry none of my replies r gettin posted....
we did consider the RPM bt v r tryin to do it with the speed of the vehicle..... as the speed increases for it to change the gears. and the part about going up hill... you need to change the front derailleur only if its a steep hill to climb. and since this is the first project we are doing we are trying to just demonstrate the idea and going to leave the uphill part for a bit later.

bt does anyone remember the title of the topic if this was already covered..? i cnt seem to find it...

 

[gary350]

hey im sorry none of my replies r gettin posted....
we did consider the RPM bt v r tryin to do it with the speed of the vehicle..... as the speed increases for it to change the gears. and the part about going up hill... you need to change the front derailleur only if its a steep hill to climb. and since this is the first project we are doing we are trying to just demonstrate the idea and going to leave the uphill part for a bit later.

bt does anyone remember the title of the topic if this was already covered..? i cnt seem to find it...

It was not covered on this forum. It was on the bicycle forum about 5 years ago.

 

[tcmtech]

If you are too lazy to shift a bicycle then you are probably too lazy to ride one as well.

With an automatic transmission in a vehicle the ground speed, engine speed, and throttle position all work together to determine up and down shift points.
On a bike you only have ground speed and a very limited engine speed equivalent to work with and no accurate equivalent to a throttle position to equate to a torque level being exerted by the rider.

 

[gary350]

If you are too lazy to shift a bicycle then you are probably too lazy to ride one as well.

YES....you are exactly right!!!!!

I do a 20 mile bicycle ride every morning and I shift the gears by hand.

 

[sakyasri]

hahaha yea u guys r right some people wont like to hav an auto gear system for a bike.... but this is a university project.

So does anyone know any place i can get some examples or something that would help.... because we are totally lost...

 

[SABorn]

Dont you read the posts, as i said before, it has all been done before, search this forum and you will find a thread with many answers.

You dont expect us to do all the leg work for you...........or do you?

Pete

 

[birdman0_o]

I think the best part is that there are 6 of them.
There is a difference between "I found these links what do you guys think" and "Please find me 10 links in the next hour it is urgent"

 

[sakyasri]

well i kept on looking but i couldnt find any...... maybe its the keywords im using, i dont know.i tried "autogear bicycles" and it gave me 97 searches.... but none of them matched what i needed.
and someone said it wasnt covered in this forum and it was in some bicycle forum.... so i thought it wasnt here...
its ok i'll keep looking...
thankx for the things so far.

 

[sakyasri]

oh and btw when i askd if there is some place anyone knows, i meant if you had already come across this or anything similar, to post it here if you dont mind.... no offense to anyone.

 

[gary350]

oh and btw when i askd if there is some place anyone knows, i meant if you had already come across this or anything similar, to post it here if you dont mind.... no offense to anyone.

Go to this bicycle Forum and log in then do a search. It has been 5 years since I saw it mentioned so you may have to post a question on the forum. GENERAL DISCUSSION is probably where you will find the answer someone there can point you in the right direction.

http://www.bentrideronline.com/messageboard/index.php

If I were building this I would buy a Slick SLC 150 on ebay it is a mini 20 input 10 output programmable computer. I would buy the 24 volt DC model. I would put a prox switch on the frame next to the pedal to count pedal RPMs. I would put a prox switch on each end of the rear derailleur. When pedal RPMs need to go faster I would program the SLC to shift to the left until RPMs reach 85 the prox switch on the far left is the left limit stop. If the pedals need to go slower I would program the SLC to shift to the right until RPMs reach 85. If you put a touch pad on the handle bars the rider can fine tune the program as they ride. The high RPM limit might need to be 85 for me or 90 for someone else and the low limit might need to be 70 RPM. You will have to mount a 24 VDC battery on the bike. Also buy a hand held programmer on ebay too.

You can buy any SLC programmer you like the SLC 500 might be a better choice the SLC 150 are old and getting rare and hard to find 5 years ago they were $20 each on ebay but not that they have become rate sellers think they are a gold mine and want $1000. The SLC 150 was about $500 brand new 20 years ago. Next generation is the Allen Bradly SLC 500. It will take you about 2 days to learn to do a simple program it is easy just experement and make it turn a light bulb on/off just to learn how it works.

You need to find a way to shift gears, maybe a reversable 24 VDC gear motor or something else might be better.

SLC 150 programmer **broken link removed**

Key pad **broken link removed**

I think this is the 24VDC unit you need to do a web search for the part number to be sure **broken link removed**

If you want to program the SLC with a computer you need this cable it is for an old 486 computer. Not many people still have those old computer you will need to buy software too. The hand held unit above is your best choice. **broken link removed**

Here is a prox switch it detects metal. **broken link removed**


If you want to try an SLC 500 here it is. If you learn industrial programming you can write your own pay check $$$$ make a $1000 a job doing programming on the side. I did programming for years there are dozens of different type SLCs all by different companies. I learned to program all the most common ones 20 years ago and did programming for 15 years. If you work for a large company you can expect to get a $800 pay check minimum every week. If you do programming on the side you can make $1000 to $2000 each job and get maybe 2 jobs a month if you live in an industrial area with lots of factories. Most factories hire their own programmers. **broken link removed**

I have been out of this business for 5 years. All the things I know how to program are probably going obsolute about now. Industrial programmable controllers are no different than home computers new ones come available all the time and the old somes become obsolute.

If your college or trade school has Industrial Electronics you can learn Industrial Programming in that class. There is a trade school here that teaches industrical electronics all the college kids look down on the trade school kids like they are a bunch of retards to dumb to go to a real college. Don't let that bother you at all you can wave your $1000.00 a week pay check in their face. If you go to law school you can make $400 an hour. If you go to optometry school you can make $100 about ever 30 minutes. When I was young and stupid and given the choice between a job I hated that paid good and a job I liked that do not pay good I took the good paying job but not anymore now I pick the job that is the most fun don't care how much it pays.