Shifter problems.

Discussion in 'Bicycle Repair' started by arkives1, Jan 23, 2010.

  1. arkives1

    arkives1 Member

    I'm working on an OCC chopper which will be set up with a shifter. I'm currently changing the bike from single speed to 5 speed. I have the gear cluster and derailleur all set, got a longer chain on, the problem is in the shifting of gears. No matter how I adjust it, I get erratic shifting, either it skips gears or will shift up ok or down ok but not both. I have tried twist grip shifter 6speed, no good. Tried 6 speed thumb shifter, no good. Just tried a shimano 5 speed thumb shifter, same results. The shifters are Shimano and both the derailleur and the shifters are made for SIS. The gear cluster is a Suntour. I suspect that the gears are not correctly or equally spaced on that cluster. Has anyone else run into this problem with shifting? I have other bikes with 6 or more speeds and all are adjusted correctly so I don't think it's my technique thats wrong here. Any comments or suggestions are most welcome.....Woody
     

  2. a/c man

    a/c man Member

    Rear derailer can be aggravating

    Is your chain the right size and length? A five speed derailer needs the 1/2"by 3/32" chain. single speed bikes typically use 1/2" by 1/8" chain. The difference in width will not jive if you try the wider 1/8" on a derailer.
    If the chain is too long it won't shift right either. To correctly size the chain thread the chain on the large front sprocket, and the largest rear sprocket without running it through the rear derailer. The chain should just connect and be 1" longer than that. Also some rear derailers have a third adjusting screw which is not a hi-lo adjuster but a chain tension adjuster for the derailer spring. It should be adjusted tight enough to almost bring the chain in contact with the smallest rear gear(5th)when shifted to that position. A bent derailer cage will also pi$$ you of by not shifting right. Hit a curb or something and a little twist of the cage with the 2 plastic wheels and you'll spend hours of fun trying in vain to remedy that. Here's a great link on derailer fixin. I hope you give that bike on more good look over before going nucken futz. Seriously check the Sheldon Brown link out. It will show you how to do the cable tensioning correctly also http://sheldonbrown.com/derailer-adjustment.html#chain
     
  3. arkives1

    arkives1 Member

    shifter problems

    Thanks A/Cman. I know the chain is the right size, it is 3/32" and the length was calculated using a chain length calculater online, plus I learned that generally adding a derailleur requires two more links than the chain would be on the two largest gears. The derailleur is a new Shimano Tourney right out of the box, never been on a bike before so it should be ok.There are three adjustment screws, high, low and sprocket to sprocket distance. The idlers just clear the sprockets on the highest gear as directed by the derailleur's instructions. (They suck by the way, so small I could barely see the print much less the diagrams) I'm afraid it may be too late to save my sanity, I've gnashed my teeth to the bleeding stage and what little hair I haven't pulled out is turning gray.:annoyed: I have another gear cluster on the way which is Shimano as well and supposed to be designed for SIS. We'll see what that brings, if that fails I'll wait til spring and hit the yard sales til I find a bike with good working gears on it at a good price and use it for parts. I'm puzzled by this one because I've had much success adjusting these things in the past on my own bikes and on all my kids bikes...Very strange....I examined the cluster again tonight trying to see if there was a variation in the spacing of the gears, I can't tell by looking at it but the chain is just missing the shifts by a very little bit no matter how it's adjusted. Fun hobby isn't it...if I survive this one, I may take up golf. Thanks again AC and I will check our Sheldon's site. Woody
     
  4. a/c man

    a/c man Member

    I also have the Shimano Tourney derailer. So far it's been the best one shifting out of the 3 or 4 I've tried. I don't have the freehub style gear cluster though, I have the older style freewheel type (one glob of inseparable gears). The freehub style you have is better and easier on supporting the rear axle.
    I know indexing that thing can take some time and patience. Good luck and by the way get a good cable designed for rear derailers, cheapies can compress the cable housing length.
     
  5. arkives1

    arkives1 Member

    Shifter problems

    Hi again A/C. Actually my freewheel is like yours, one glob of gears. It has Suntour stampled on the outboard side of it. It does look like each gear is a separate piece separated by spacers, they all turn together. The spacers are different colors, some are chome like and others look like brass maybe. I read through Sheldon Brown's web site last night, excellent information and well written and easy to understand. It seems I did everything as he describes. He mentions using mismatched shifters and sprockets as no problem. I mean like using a 6 speed shifter with a 5 speed gear cluster. I originally thought they would be spaced differently but apparently are not, it's just that a 5 would have as shorte stack height than others. All that being said, I still think the problem is with the gears themselves. The cables are made for this purpose and were made my an excellent local bike shop that's been here for over 50 years. They should know a thing or two. When the replacement freewheel is here and installed, I'll let you know if that helps any. By the way, we discussed chain length, when I was doing this I found online a calculator and a formula using the chain stay length, the diameter (number of teeth) of the two largest gears and doing a bit of math. Both methods gave me the same answer, 78 inches or 78 links for the OCC with derailleur. I thought perhaps the long chain stay (close to 30) inches might be causing some sort of twist or bounce in the chain causing the missed shifts. Keeping tension on the upper chain and shifting slowly didn't change anything, still got the same bad shifts. It's an interesting and challenging problem that I'm determined to solve somehow. Thanks for the interest and help. Woody
     
  6. arkives1

    arkives1 Member

    shifter problems

    after a lot of re-engineering and experimenting with various derailer/shifter combinations I think I finally found the root cause of the problems and have found a solution. It seems that because of the way the frame on this bike is shaped the sprockets on the derailer couldn't get close enough to the gear cluster for proper shifts. It was also hanging up on the frame. I finally found a derailer with 5 positive stops on the derailer and none on the shifter. It's called a Shimano Positron and predates the newer index shifting designs. This thing has no spring to pull the arm in or out, it uses a push/pull cable. A rigid wire like piano wire pulls the lever one way and pushes it the other way. It was very easy to adjust and seems to work in a positive manner. Shifting is easy and smooth, no erratic gear jumping or missing a gear. I had to make some modifications to make it work in the push mode but got it done easily. These shifters and derailers are old school and not so common as others but it does seems to have solved my problem. Seems like a sensible shifting design but it didn't have a very good reputation or wide spread acceptance in it's day. It's called a Shimano Positron and it uses a dual lever shifter with whats called posi-cable. The second shift lever was meant to shift the front crank derailer system. The bikes these were used on had freewheel cranks supposedly to allow shifting while coasting or changing gears for cornering or sharp curves. I've had a real education on shifters and derailers and I'll bet there are more surprises ahead. In case anyone else builds a shifting OCC Chopper this might save you a lot of head scratching and hair pulling. Woody
     
  7. a/c man

    a/c man Member

    Wow, you paid your dues on that shifter dilemma, glad you finally found
    something that works. Never heard of that type of derailer, sounds kinda cool!!
     
  8. retromike3

    retromike3 Member

    Shimano Positron

    I remember one of the first index systems was the Shimano Positron. It was a horrible system and only was on the worst bikes available. It was about five years before they came out with the Dera Ace S.I.S. system. I still remember those one size fits all cables(much like the throttle cables most kits come with.)and the cheep steel derailleurs. Just because it was make a long time ago does not improve its quality. It is a single parallelogram derailleur and does not track evenly from the largest to the smallest cog.

    If you want to cruse memory lane I would recommend the 1989 Shimano Deore seven speed with a 14-28 freewheel. those systems were bomb proof and beautiful. Whatever you did you could not make them fail and with only 130mm axle spacing the hubs were almost indestructible.

    Mike the bike guy
     
  9. arkives1

    arkives1 Member

    Shifter problems

    Your information is much the same as mine Mike, I did read about the poor reputation and that the quality was not good. However, so far this is the only one that's worked right and shifts easily and smoothly. I have no idea how long it will last but I'll give it a try and I'll keep the info from you filed away in case I need to replace it. This has been very frustrating. Nothing seems to work easily when converting an occ chopper to a multispeed. Woody
     
  10. retromike3

    retromike3 Member

    multi speed

    Have you considered an internal hub? Shimano makes a nexus five speed and Stermy Archer makes a seven that I think might hold up to a MB.

    Mike the bike guy
     
  11. arkives1

    arkives1 Member

    Shifter problems

    Actually, I did consider that at first, but decided I didn't really want to invest that much in this bike and I really didn't care to relace the wheel. I may yet decide to do that depending on how this works out as I have it now. If so I will likely try to get a better brake system as well. I was able to add front caliper brakes and had rim brakes on the back already. I'd prefer disc. The triple tree front end makes disc brakes very difficult.
    Woody
     
  12. Breuklen

    Breuklen Banned

    If you use a teflon lined cable housing with grease it will cause the problem you complain of. Also try using shimano sis inner and outer cables. If you use coil wound wound outer cables on anything more than a 5 speed index shift system. you will have this problem. Coil wound outer cables compress when the cable is tensioned,therefor the degree of accuracy needed to maintain for 6 speed and higher drive rains is compromised. in other words coil wound cables act like a spring under tension. Using shimano sis linear cables will rid your problem! Make them as short as possible and make sure the radius's arent too tight. Do not kink them or they are ruined forever!!
     
  13. arkives1

    arkives1 Member

    Shifter problems

    Thanks Breuklen ....I did solve that problem with an old positron shifter and a little skid plate on the bottom of the derailleur. Because of the way the frame is made the derailleur was dragging and hanging up on the frame causing the problem. After that modification it worked very well and still shifts nicely.
    Woody
     
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