RADBMX.CO.UK
Technical & Reference Section => Tech and Restoration => Topic started by: sweetbeats on October 30, 2008, 01:43 PM
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Alright,
Fitted a new izumi chain last week and have noticed that in one part of the chain it is fine but if i turn my cranks half a turn it is tight as anything!
Is this just down to being new or is it a piece of jap crap any ideas? :daumenhoch:
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Can you put a pic of the complete drivetrain up dude?
:daumenhoch:
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What bits that?
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somethings not quite inline
could be back wheel not sat square or probably on the cranks area as in chainring
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Is it a left handed or right handed chain you're using?
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This is caused by a warped chainring, I believe (but could be wrong). I think you can get rid of the problem by putting spacers/washers on some of the bolts.
Please correct me if I'm wrong but I have the same problem on my Haro.
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Does it have a spider/chain ring set up?
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This is the set up,dont think it is the chainring as it was brand new and the powedisc is minty too...checked wheel and looks pretty square...do you think the problem will ride out..I only built this last week and already i am thinking of selling it...it is just making me angrier and angrier :D even looking at this picture i want to smash it up :4_17_5:
(http://www.radbmx.co.uk/archive/albums/ll418/jasonscottpics/DSC00910.jpg)
any old freekin iron!
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More than likely the chainring & spider on the crank slightly off centre. you can mess about with it to improve things by loosening off the chainwheel bolts & retightening them (without the chain on) & also loosen & retighten the spider on the cranks. Also watch your freewheel whilst cranking the pedals backwards & forwards, is there any 'wobble' in the freewheel at all?
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I have the exact same mirage disk and sugino chain ring, one of them will definitely be warped slightly, a washer should fix it. Am I right, Bob?
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I will have a look after my tea...it really is starting to drive me nutz this bike..been getting on my ti@s since I started it :LolLolLolLol:
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More than likely the chainring & spider on the crank slightly off centre. you can mess about with it to improve things by loosening off the chainwheel bolts & retightening them (without the chain on) & also loosen & retighten the spider on the cranks. Also watch your freewheel whilst cranking the pedals backwards & forwards, is there any 'wobble' in the freewheel at all?
Checked freewheel no movement at all :daumenhoch:
Hi lucy where would i put the washer?
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Are you using a reducer/top hat so that the spider fits the spindle?
If you are, was there any play when the spider, top hat and spindle are assembled (before you tighten up)?
If there is then the spider might be slightly off centre!!
Also try loosening off the Chainwheel bolt on your crank arm. Just to check whether tightening the chainwheel bolt has caused the spider to pull out of alignment. If it is then you might need a washer between the crank arm and spider where the chainwheel bolt goes through to take up the slack so that when you tighten it it doesn't warp the spider.
If your spider is warped where chainring bolt is attached then it would cause tightening in that area!!
When the Chainring bolt area is off the chain (between the top and bottom of the chain) then it will feel loose!!
And tight when the chainring bolt area is furthest from the Freewheel!!
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Cheers Fella I will have a muck about with the bolts shortly and see what happens :daumenhoch:
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When I've had issues like this before I always start with checking the run of the chainring.
I start by removing the chain.
I then use a pen/pencil and hold across the chainstays with the tip next to the edge of the chainring teeth.
Then I turn the cranks and see for sure if there's wobble, or back to front movement showing it's off-center on the spindle.
It doesn't have to be too far out for it to create major slack/tight rotations.
Then I'll put a long straight edge along the chainring and back to the freewheel to see if that's out.
On a couple of builds where I've had this problem I put the chain back on the bike.
Then turn the crank so it's at it's most tight, then undo the chainring bolts.
I then pinch the two sides of chain together and tighten a couple of the bolts.
Spin the cranks a couple of times and see if it's loosened a little.
9 times out of 10 with a bit within 2 or 3 attempts the problem is sooo much better.
Just my tuppence worth :daumenhoch: G.
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Cheers Gremlin Ill have a tweek later on see if I can sort it :daumenhoch:
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Dont remove the chainring/spider bolt. Just fully loosen it!!
Then spin the cranks. if its now loose (or the same) all the way around then tightening the bolt must be warping the Spider.
Are you using a top hat washer?
The top lip of the top hat washer has effectively moved your crank arm that distance from the spider.
Therefore you need a washer the same width between your crank arm and spider!!
Order - Chainring bolt - Spider - Washer - Crankarm Chainring bolt hole.
You can check whether you need a washer with the crankset off your bike by placing your crank arm, top hat, spider on the spindle. Push it all together with your hand. If the spider isn't flush to the crank arm chainring bolt area then you need a washer to fill the gap because tightening it will only move the spider out of alignment!! :daumenhoch:
If this isn't your problem then follow Gremlin's advice for the Chainring as that is the most common place to cause alignment problems!!
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I've just had a proper look at your pic ::)
What type of Redlines are they ? Single/twin pinch, model etc...
:daumenhoch: G.
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I've just had a proper look at your pic ::)
What type of Redlines are they ? Single/twin pinch, model etc...
:daumenhoch: G.
Unsure of model single pinch 180's though
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IF none of the above works try this :
Items needed : Vice, Rags, Sledgehammer, Cold drink (Beers always good), Loud music, Pc with Internet connection.
Step 1 : Carefully wrap chainring & spider in rags.
Step 2 : Place carefully wrapped chainring & spider in vice and slowly tighten up.
Step 3 : Turn on loud music (Metalica's a good choice).
Step 4 : Open your beer and down it in one.
Step 5 : Start gentley tapping the chainring with sledgehammer in time to the music.
IF THAT DOESN'T WORK TRY STEP 6 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Step 6 : Go to your Pc and look up those lovely people at the RADBMX.COM shop and see if they have a new straight one instock. :2funny: :daumenhoch: :2funny:
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You can always replace the crank arm bolt which stops the spider from rotating with a suitable set screw (grub screw) (no 'head' on it) this will stop the spider rotating as intended but will not pull the spider out of true when tightening it down :daumenhoch:
In my experience the top hat washer should be inserted into the spider from the inside (BB side) not the outside (crank arm side)?
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Mirage power disc, loose it, they are shit. Had about 3 now and not one has been centred correctly. You always have tight and slack spots in a chain it's just the extremety of it that dictates wether you do anything about it or not. Buy a one piece flite ring with correct centre for your cranks and you will notice a big difference.
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Just live with it, every one of my bikes, new or old school, have tight/loose spots in the chain and no matter what I do they stay :(
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Cheers Bill It has driven me nuts so I have decided to try and swop it for HUTCH...only built it last week but not feeling the :smitten:
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In my experience the top hat washer should be inserted into the spider from the inside (BB side) not the outside (crank arm side)?
Not if your top hat is deeper than the spider/chainwheel. Then you have to put a Bowler hat (thingymajig) washer on the inside so it can tighten up!!
Thats how I noticed it getting pulled out of alignment!! :shocked:
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Going to have a blast out to the offy later see how she goes...haro bitch :tickedoff:
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Same as Bill, all i've ever done, is position it so chain is correct tension at tightest point, but make sure that it is not too slack at slackest point :LolLolLolLol:
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:LolLolLolLol:
Going to give her a pounding now :daumenhoch:
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pretty mudh as moley says unless the power disc is not holed central .listen to him ive had this problem so many times and hes spot on to clear it up
:daumenhoch:
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In my experience the top hat washer should be inserted into the spider from the inside (BB side) not the outside (crank arm side)?
Not if your top hat is deeper than the spider/chainwheel. Then you have to put a Bowler hat (thingymajig) washer on the inside so it can tighten up!!
Thats how I noticed it getting pulled out of alignment!! :shocked:
Break out the files & make it fit :daumenhoch:
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It was made out of some hardened metallic kryptonite or summat!!
Fook that, it could take me ages to file it and I'm far too lazy!! :(
Luckily Bof had a bowler hat jobby to fit it!! :daumenhoch:
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I've had this problem on both BMX and MTB singlespeeds, it has driven me nuts too as I like to run quite a tight chain.
I couldn't put it better than Gremlin, if your still not sorted check his post again.
Good luck.
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Jay
What you need is a mallet, not one like this ...
(http://www.radbmx.co.uk/archive/albums/e295/claireholden/stuff/timmysessionsept20022.jpg)
but one like this...
(http://www.kctools.com.au/images/TOOLS/TOOL%20JPEGS/TOOL%20JPEGS%20INC%20DESCRIPTION/10320%20RUBBER%20MALLET.jpg)
Tap the spider into alignment and problem solved :daumenhoch:
Marty ;)
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Thanks for all your help fellas,
been out over the weekend and gave the pedals a pounding and the tight spots have slightly eased,think I will ditch the mirage power disc and get a trusty spider or redline bubble ;)