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Thread: Aligning Flywheels & Chains

  1. #1
    Join Date
    Mar 2004
    Southwestern Sheboygan, Wisconsin USA

    Default Aligning Flywheels & Chains

    For some reason lately I've been having problems getting flywheels to line up and chains to drive without a lot of noise or rattling.

    We have six year old (black) Star Trac Spinners. I have been replacing the bottom brackets and chains on all of our bikes. Seems like just about every other bike I've been having problems with the alignment of the flywheel and chain. After I R/R the BB and chain I re-seat the flywheel. I turn in both alignment screws the same distance until the chain starts to snug. I then check the alignment of the flywheel with the bottom of the bike frame and measure the distance from the flywheel to the side frame to make sure the flywheel is properly aligned. (If it is not I will adjust the adjustment screws accordingly). I then continue to tighten the adjustment screws until I have the desired tension in the chain - tighten the lock nuts on the adjustment screws - and tighten the axle nuts.

    Still after doing this some of the chains seem to have an excessive amount of side-to-side vibration and/or noise (pinching or grinding) up at the front ring. I know the replacement chains and BB are the correct size. I am wondering if it could be a problem with wear (or bending from wear) in the drive chain ring or front ring.

    If anyone has some thoughts I would love to hear them. If anyone sees a flaw in my alignment procedure - or can suggest a better way - please let me know.

    FYI I do have a copy of Studio Cycles Tech Manual.


  2. #2
    Join Date
    Mar 2004
    Western Wisconsin
    Blog Entries

    Default sprockets

    I had a similar issue recently. in my case I changed the sprockets this helped. I don't know if your issue is the same or not. Just a thought how are the bearings?

    good luck

  3. #3

    Default It's the sprocket!

    Replacing the BB and the chain will not fix the issue. The sprocket/chain rings on most bikes are stamped out of metal plate and not machined to a very high tolerance. The quality of the steel is not that good either. The wear pattern created, over time, due to the above will see a new chain have a bigger tight/loose spot than the worn chain. The noise will be worse also.

    To get the best results the sprocket/chain rings need replacing.

    Good luck. Revs

  4. Default

    I share in your frustrations. I think most has to do with the tolerances these bikes are built at. I replaced flywheel, front sprocket, bottom bracket, chain and chain ring with brand new components. I did all the proper alignment and setup as per JW's book. The noise lessened, but not where I hoped it would be.

    As for aligning the FW/sprocket to be parallel with the chain, could you explain more. I am looking for a more fool proof way to make this happen and knowing the tolerences are out on the bike (frame to FW distances not always accurate) I have resorted to eyeballing how the chain falls onto the sprocket.


  5. #5
    Join Date
    Mar 2004
    Southwestern Sheboygan, Wisconsin USA


    Zoe here's what's been working for me. Most of the time I start from scratch. Loosen the axle nuts. Then I turn out the adjustment screws until the ends are flush with the inside (front-most side) of the frame. Then I turn both sides in 23.5 times which is about how much is needed to get the chain to start to snug. Then (facing the front of the bike) I measure the top (chrome) of the flywheel to the outside edge of the (black) frame and then the bottom (chrome) of the flywheel to the outside edge of the same (black) frame. The distance should be in the area of 1.75". Top and bottom measurements should be pretty much the same. Then I do the same to the other side. If the bottom measurement on either side is off I will make the adjustment while there is still slack in the chain. (If the bottom measurement on the drive side is more than the top - you'll want to gradually tighten the non-drive side adjuster until things measure up on the other side) When all four measurements are near identical I will gradually tighten both adjusters (back and forth) until I have the desired chain tightness. Before I tighten the axle bolts I'll spin the wheel and eyeball it with the bottom frame member to make sure it rolls true. I'll also watch the chain as it feeds into both rings to make sure it is feeding the center of the chain. If all looks good - I'll tighten her up and give her a test drive.

    If anyone can improve on my method please do.

    I have learned through experience - you can't be in a hurry when adjusting a chain and/or flywheel. At times it can try your patience.

    Good luck.

  6. Default


    I follow a lot of what you do except the measurements. I usually rely on my ear and eye to align these puppies. Without major issues I can do a room full of 30 bikes in 2-3 hours. However, that does not mean everyone needs adjustments. Rarely does a bike take me more than 5 minutes and most would be considerably less. For the ones that are over 5 minutes it usually is a sign of wear on a part - so I replace. Maybe I am fortunate that most of mine (currently serving about 60 bikes) are in good shape because the gym;s allow me to maintain on a weekly basis, so not much gets too far out of whack

    I, too have found that the premise of adjusting only one side of the axel leads to wheels that are more "OUT". I always do both sides.

    Would love to hear Jeff's feelings, technique on adjusting these.

  7. Default A loose nut

    Hey Cheese,
    I would guess theres a loose nut behind the wheel

    Sorry, I couldnt resist!

    You can contact me directly next week if you want to talk.I am currently in San Francisco on behalf of Schwinn with my Platinum Tech Support program.

  8. Default

    Hello I am new to the forum,

    I realize this is an old post but I am having this very problem with a Schwinn Johnny G pro. I thought logic would dictate that if I measured from center of axle bolt to center of bottom bracket bolt I would have the axle and bottom bracket parallel and all should be good. But the flywheel appears slightly out of square to the frame and the flywheel is not properly centered between the forks. The measurements are close pertaining to square with frame and parallel to forks. I am checking with measurements and squares.
    Does the parallel axle to BB sound like it should be the appropriate way to go about this or are the other square to frame/parallel to forks measurements the way to go???
    Any help appreciated.


  9. #9


    ....... I miss Realspindoc......... Brayn,I'll respond later when I get back from work as it's more an "eye" thing than measurements.

  10. Default

    Yes I have been watching alot of the Realspindoc and was sad to hear of his passing. I am new to knowing of him as I have been researching spin bikes in the last few months. He is the reason I looked for a Johnny G.
    I am a carpenter and am fanatic about measurements and keeping things square, straight, true. I have picked this machine apart and the base is square to itself as I checked via the 6/8/10 method at each end. Therefore it is feasible to line up the flywheel to the center bottom beam. But the forks are not parallel to each other and the center of the flywheel is not at perfect center between the forks as result of or due to the axle spacers, sprocket etc not allowing it. So measuring off of the forks does not work on my bike. But with the flywheel lined up perfectly with the bottom beam, the axle is perfectly parallel with the bottom bracket. I am using logic here(which doesn't always work ). But how can it go wrong if the bottom bracket and flywheel axle are perfectly parallel? I was trying to find a quick method of getting the flywheel set and it seems to work.(on my bike anyhow).
    I haven't ridden her yet so all my theories may fall apart in the morning when I try the bike out.
    Thanks for the response Rick. I look forward to hearing how you align the bike.

  11. #11


    Jeff knew everything there was to know about indoor bikes and I was lucky enough to ask him just a few questions,sit in on a couple of workshops and visit him in his new (at the time) facility.

    Ok,so every single time I have had to line a wheel up i have done it by ........ looking at it.I listen to the pads as the wheel rolls through as well.There is no science to it (how I do it,that is) but I have always been able to feel it right.


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