Problem with my new/rebuilt wheel

Discussion in 'Frame Mounted Engines' started by Hajuu, Mar 7, 2010.

  1. Hajuu

    Hajuu Member

    Hmm. After readjusting my wheel and tensioner again (my new ones), i've run into an interesting problem..

    Basically, with my old wheel, the hub was a uniform size which allowed me to slide the drive sprocket right upto the edge of the wheel. On this one, the hub was non-uniform in size, and thus I had to use the rubber gasket between the sprocket and the spokes/hub.

    Now however, the chain even running the tensioner very close to the rear sprocket, I still get barely any clearance between the frame and the chain, and it also doesnt seem to like the angle the tensioner is on either.

    The clearance of the chain seems to me to be ok, the tensioner is maybe a bit of a tight fit but it doesnt seem like itd cause any terrible issues.

    Now my symptoms of the problem are that when I start riding, I am met with a very shakey, shuddery ride, with kind of like, smaller bursts of power. At higher speeds this becomes nothing and it runs as normal.

    As far as I can tell there are three possible causes but im unsure as to which it is most likely to be..

    1. The rear drive sprocket isnt 100% true
    2. The chain is too tight
    3. The tensioner isnt at the right angle and is causing the chain to stick, but power through it at higher speeds.

    Any ideas?
     

  2. AussieSteve

    AussieSteve Active Member

    So, previously you didn't use rubber on both sides of the spokes?
    I got two rubber gaskets with my kit and used one each side of the spokes.
    You didn't have trouble with the sprocket hard up against them?
    If not, could you possible enlarge the hole in the centre of the sprocket to allow it to fit the way it used to?

    The tensioner needs to be really carefully aligned by bending/twisting to guide the chain onto the centre of the rear sprocket, especially when it's close. The centre is an average of it's side-to-side wobble as it turns.
    (I had mine fairly close, before I threw all that junk away and bought the shift-kit. Best addition to the bike so far.)

    Double-check chain tension by lifting the rear wheel and rotating it to where the chain is at it's tightest. You want it almost tight. Then, rotate the wheel until the chain is at it's loosest and see how much play there is. If too much, you might need to re-centre the sprocket.

    Also, if side-to-side wobble in the sprocket is more than about 5mm, it can cause problems.

    Get a piece of string and check sprocket alignment, too.

    ... Steve
     
    Last edited: Mar 7, 2010
  3. Hajuu

    Hajuu Member

    Nah, before now I used a layering like: 3 part bracket, rubber, spokes, sprocket (facing opposite way to directed), rubber, 2 part metal bracket, bolt ends.

    Now the layering is: 3 part bracket, 2 part bracket, rubber, spokes, bolt ends

    I think, by the way the rubber is taking up the gap perfectly, enlarging the sprocket hole would be a mistake. Its much more likely this is the way its meant to sit (it seems to me atleast).

    The tensioner is definately a gum in the works, is it going to be a terrible idea for me to blowtorch it and bend it, because I dont really have a vice or anything here for heavy duty bending etc.

    Also: While on my test ride today I noticed that after a while of riding it at high speed (remember I said riding at high speed seemed to be ok but low speeds were having big issues), afterwards on the way back, performance really dropped. Is it possible that the friction on it was so much that it heated up and stopped spinning. And would this have had said effect on performance?

    I also thought that rolling a bike and seeing either it getting looser or tighter was a sign your sprockets weren't aligned/true?
     
  4. AussieSteve

    AussieSteve Active Member

    You say above that currently there's no rubber between the sprocket and the spokes, only on the inside of the spokes. Is that true, or is what you said in the original post right. You're confusing me. This is what you said in the original post:-

    Dunno what to say here - depends on the above


    Blowtorch, what for? The only way to do it properly is to clamp it very firmly in place, then bend/twist until it's perfect. All you need to bend it is a large shifter or even a 20cm one with a foot of pipe on the end.
    I did mine that way and I'm a 50kg weakling.


    I don't understand this. Friction on what was 'so much that it heated up and stopped spinning'?


    If you re-read what I said, that was my point.


    In summary, just really have a good look at things with the rear wheel in the air so you can turn it as you work. Double-check everything and use your head a bit. It can't be too much of a mystery. Check alignment with string or a straight-edge as suggested, too.
     
  5. Hajuu

    Hajuu Member

    Opposite way around :)

    Now I have rubber between the spokes and sprocket, before I didn't.

    Sorry if my posts are hard to understand heh, I tend to use the word 'it' often instead of saying what a comment is about.

    With the blowtorching the bracket thing, its simply because I don't have any vices, clamps or even a big pair of pliers, i'll give it a go without heating it up. Heating it up, bending it, and cooling was just my initial thought back from my days in metal work at school.

    Cheers mate
     
  6. AussieSteve

    AussieSteve Active Member

    Glad you've got rubber on both sides of the spokes. Much gentler on the wheel.

    You'll find that it's actually easier to bend the tensioner into position when it's clamped onto the chainstay. Try to only twist or bend it right near the bottom, close to the chainstay, if possible. I also replaced the original bolts with a pair of 8mm high-tensile bolts, from SuperCheapAuto, so I could tighten them more than usual.

    What was the friction thing you mentioned? Did you mean to ask if the engine was maybe getting too hot and beginning to tighten up, (seize)?
     
  7. happycheapskate

    happycheapskate Active Member

    I think he means the roller on the tensioner was binding up.

    Make sure your chain is thoroughly lubricated. When I first started running my Grubee kit I thought something was wrong with it because their was a lot of vibration, but soaking the chain in motor oil and then keeping it greased has cut way down on friction.
     
  8. AussieSteve

    AussieSteve Active Member

    Actually, now that you mention it, I had to add an extra washer to my roller to stop it binding.
    Then, so I could tighten it properly, I filed the head of the pin to take a 14mm socket, like this. (It's not as off-centre as it looks.):-

    [​IMG]
     

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