Q Rings and chain length

brettjmcc

Hi, can anyone advise if you need to alter your chain length in general when switching to Q Rings?

I had to return my Rotor Dual PM and they have sent me an IN Power replacement along with Q Rings to make the difference up. It only turned up yesterday so not had time to fit to the bike and wanted to know whether I might need to go get a new chain(s) for when I put the new crank in (and therefore get some chains on order). Thanks

Brett

keef66

No direct experience, but logic suggests if they have the same number of teeth, the oval rings will require the same chain length as round ones, no? The front mech will obv. need to be higher.

philbar72

same number for me works fine. front mech stays slightly higher. that's it. I run either 52/36 Q or 52/38 Q and runs just fine.

StillGoing

You need a longer chain. Q rings act as a bigger chain ring when engaged in the full oval so if you're ever in the big end of your cassette and the big chain ring, the chain won't have enough reach and will most probably rip your rear mech off or at the very least bend it. A 52 tooth Q ring will represent something like a 50 when in it's small oval and a 54/55 when in it's biggest oval. Watch the clip and he eventually explains it quite well.

https://youtu.be/gzPOICdSZaU

keezx

Doesnt make any sense, 54 T=54 T

StillGoing

Keezx wrote:

Doesnt make any sense, 54 T=54 T

A 54 tooth Q ring isn't just 54 teeth if you watch the video. At it's narrowest it will be around 2/3 teeth less and at it's widest around 2/3 teeth bigger. Watch the rear derailleur as a Q ring is used and you'll observe it moving backwards and forwards as the chain tensions and un-tensions. If you were to find yourself in a big/big combination, as many do momentarily, you'd be putting stress on the chain and rear mech. Me personally I would check the chain length with the largest sprocket on the cassette and with the Q ring at it's biggest oval.

brettjmcc

Thanks all, will check.

I can't even get passed the first stage at the moment, the replacement IN Power sent won't even appear to switch on

Chris71127

I'm running Q rings and replaced like for like in relation to the number of teeth and kept the same chain.

I have had no issues at all other that tweaking and raising the front mech.

svetty

Whilst the diameter of the chainring varies during rotation the circumference doesn't. However the effective circumference with respect to the amount of chainwrap on the ring does vary - hence the movement of the rear mech during pedalling. Unless you are right at the limit of your chain it is unlikely that the variance will be an issue but if your chain is borderline short to begin with you might just get caught out in 'big-big'.

StillGoing

Svetty wrote:

Whilst the diameter of the chainring varies during rotation the circumference doesn't. However the effective circumference with respect to the amount of chainwrap on the ring does vary - hence the movement of the rear mech during pedalling. Unless you are right at the limit of your chain it is unlikely that the variance will be an issue but if your chain is borderline short to begin with you might just get caught out in 'big-big'.

The point I was trying to make put much simpler.