chain hitting frame

  • Discuss chain hitting frame in the BMX Bike Tech forum in area BMX-Forum Community; is it me or any gearing below 30 - 11 chain hits the frame, even when bunny hopping? ...
A-J

A-J

New Member
chain hitting frame post #1
is it me or any gearing below 30 - 11 chain hits the frame, even when bunny hopping?
 
bmxinspired

bmxinspired

New Member
chain hitting frame post #2
shouldnt if your chain is tight
 
F

frightmare

New Member
chain hitting frame post #3
run a small strip of grip tape or a small sticky tube patch there to stop it from hitting.
 
purplebmx23

purplebmx23

New Member
chain hitting frame post #4
mine was hitting the frame, and rubbing off a shitload of paint but not anymore, i tightend it lol
 
A-J

A-J

New Member
chain hitting frame post #5
even when my chain is tight it does it, oh btw im running 24 - 9
 
F

frightmare

New Member
chain hitting frame post #6
im 22/8 and i dont have a prob.
 
johnuk

johnuk

New Member
chain hitting frame post #7
Check this thread out I started

Chainstay tensioner

I ended up getting a Lizard Skinz chainstay cover - I couldn't really find any suitable chainstay tensioners

 
Pickles

Pickles

New Member
chain hitting frame post #8
I have a bama. I run a few strips of electrical tape around the drive side chainstay.

24/9...might just be too tight on your frame. I run 30/11 on my bama and its running fine. used to be loose so I taped up the places where the paint got rubbed off so it wont rust.

your chain tension should be set up so that you can take your chain,push it down so you cant anymore,then push it up so you cant anymore,just by your simple strength,dont push it. they travel between the lowermost and uppoermost point should be around 10mm.
 
A-J

A-J

New Member
chain hitting frame post #9
my chaint has a tight spot, i dont no why as my sprocket isnt bent :S
 
jp0pcorn

jp0pcorn

New Member
chain hitting frame post #10
my chaint has a tight spot, i dont no why as my sprocket isnt bent :S
your chains probably just rusted in one spot, thats what happened to mine. except mine was so bad that i couldn't even move the links with my hands no matter how hard i tried... not good. Try cleaning your chain and if you can't get it to move freely i'd say get a new chain cause it can mess up other things
 
johnuk

johnuk

New Member
chain hitting frame post #11
check the sprocket is concencentric on the axle - so when you spin it and look at it from the side the teeth don't seem to move up and down as it rotates

also, if you have your chain done up really tight to try and stop it hitting the frame, it pulls on the bearings in the bottom bracket in a way they don't like, so the chain will seem to get stuck in certain places
 
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A-J

A-J

New Member
chain hitting frame post #12
my chain is sparkling clean.
 
A-J

A-J

New Member
chain hitting frame post #14
no rust or tight links
 
johnuk

johnuk

New Member
chain hitting frame post #15
check the sprocket is concencentric on the axle - so when you spin it and look at it from the side the teeth don't seem to move up and down as it rotates

also, if you have your chain done up really tight to try and stop it hitting the frame, it pulls on the bearings in the bottom bracket in a way they don't like, so the chain will seem to get stuck in certain places
not rust or weird links, this ^^^^

the chain has to be tight though for that to happen, i mean so it moves just a few mm when you squeeze it with your fingers

also check you don't have your rear axle bolts done up uber tight. they should be tight but you don't need to put lots of effort into getting them tight enough. too much squeezes the driver and hub together too tightly
 
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A-J

A-J

New Member
chain hitting frame post #16
i checked that and it doesnt look like it is, but say if it was how could i change that?
 
Jeff_Healitt

Jeff_Healitt

New Member
chain hitting frame post #17
MY CS is all chipped up. I run 25-9 and it's bad. Oh well kinda thing though.
 
hunt3r

hunt3r

New Member
chain hitting frame post #18
i think it sounds sweet when you land something and it goes 'tink'
 
A-J

A-J

New Member
chain hitting frame post #19
i dont, and my bike is silent, then makes a tink sounds ***, so atm i got plasters on my chainstay
 
johnuk

johnuk

New Member
chain hitting frame post #20
Your sprocket can be eccentric if there's any play between the hole in the centre of it and the axle when they're going together - so instead of rotating perfectly around it, there's a tiny egg shape to it as it goes round. But that'll only make any difference if the chain is real tight and it's quite bad.

I have chain tensioners on mine. When I do the tensioners up I spin the cranks backwards really quick with a finger and make sure I don't feel any patches in the spin where they get any tighter than elsewhere.

The tink noise gets on my t1ts also - my bike is silent without it. I haven't had a good enough chance to try out the chainstay cover - I popped my tyre just after getting it - but it did seem to help.

I think this is a problem with such small gearing. The best way to fix it 100% is to put a freewheel on the chainstay that pushes the chain away from it - that way it's impossible for the chain to ever bang into the frame. But there aren't a whole lot of people who make chainstay tensioners, and most of them are for MTB. You can get quite a lot that go on the rear axle and push the chain up or down - but pushing it up is just going to make it worse, and down probably won't fix it either if you land hard. Seem to kind of defeat the point of small gearing if you then need to start adding more junk to your bike to make it work properly.

The Lizard Skins protector is thin enough to fit between the chain and frame without catching on the chain, but it's a few mm thick and spongy so it soaks up knocks.

If you can move your chain 5mm or more with your fingers when you push it, it's almost definitly not too tight, you might need to clean the bearings if it feels like they're getting harder to spin at certain points. Mine were making some horrific noise each rotation. I have Euro's so I can unscrew the shells, then use a bottom bracket spacer to tap the cartridges out with a hammer. I pulled the seals off the cartridges, washed them out with solvent, then used a syringe to pack them with red Teflon before I put it all back together - silent and smooth.

As if Profile were purposefully taking the piss, the shells of their brackets need a wrench that is about 1mm bigger than any standard inch sized adjustable pipe wrenches you have lying around
 
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