# front derailer chainstay angle



## fordshov8 (Dec 4, 2009)

how important is the chainstay angle of a front derailer i have a giant trance that has a lx derailerwith chainstay of 66 to 69 what would happen if i put one with a chainstay of 63 to 66, i am going to put an xt on it, i dont even know if the lx is the original derailer or not was just wondering what your thoughts were on this


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## kapusta (Jan 17, 2004)

fordshov8 said:


> how important is the chainstay angle of a front derailer i have a giant trance that has a lx derailerwith chainstay of 66 to 69 what would happen if i put one with a chainstay of 63 to 66, i am going to put an xt on it, i dont even know if the lx is the original derailer or not was just wondering what your thoughts were on this


I have no idea what you are asking What is a "_chainstay angle_"? What is a "_derailleurwidth chainstay_"? What do 66 and 69 refer to? Use punctuation.


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## markf (Jan 17, 2007)

those were all bicycle related words, but they didn't make a lick of sense. are you asking about bottom bracket width or something? very confused.


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## fordshov8 (Dec 4, 2009)

On the back of the derailer it says chainstay angle, 63-66 or 66 - 69 degrees. So it must be the the angle of the rear triangle, or its the angle of the tube the derailer sits on I actually have no idea, I always wondered about this so thought I would ask since Im going to get a new derailer


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## kapusta (Jan 17, 2004)

fordshov8 said:


> On the back of the derailer it says chainstay angle, 63-66 or 66 - 69 degrees. So it must be the the angle of the rear triangle, or its the angle of the tube the derailer sits on I actually have no idea, I always wondered about this so thought I would ask since Im going to get a new derailer


OK, I looked it up, and the chainstay angle is the angle between the chainstay (a real or virtual line between the bottom bracket and rear axle) and the seat tube (the tube that the front derailleur attaches to).

I can't help you beyond this, other than to say that i have never heard of this term until now, and have never needed to know it when buying a front der.

In fact, I am not sure how to calculate this for a suspension bike. Is it measured at sag?


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## shiggy (Dec 19, 1998)

fordshov8 said:


> how important is the chainstay angle of a front derailer i have a giant trance that has a lx derailerwith chainstay of 66 to 69 what would happen if i put one with a chainstay of 63 to 66, i am going to put an xt on it, i dont even know if the lx is the original derailer or not was just wondering what your thoughts were on this


The chain would be more likely to drag on the bottom of the FD cage when on the inner chainring. The 63-66 FD are for frames with more BB drop, such as 29ers, where the 66-69 FD cage would hit the chainstay.


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## Snipe (Mar 6, 2005)

I know this is an old thread. I had never heard of chainstay angle either till now when I am going to order a fd for a tallboy 29er Can I assume that the 63-66 is for 29ers and road bikes and the 66-69 for 26" wheels. It does make sense that the angle will be smaller the bigger the wheels if the bb stays at the same height. but are we splittling hairs. will the cage actually hit the chainstay if you choose the wrong derailleur. I can see that the chain might drag on the bottom of the cage if you used a 63-66 on a 26er. but does this happen in the real world and is it worth concern. any thoughts.


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## Deerhill (Dec 21, 2009)

Snipe said:


> I know this is an old thread. I had never heard of chainstay angle either till now when I am going to order a fd for a tallboy 29er Can I assume that the 63-66 is for 29ers and road bikes and the 66-69 for 26" wheels. It does make sense that the angle will be smaller the bigger the wheels if the bb stays at the same height. but are we splittling hairs. will the cage actually hit the chainstay if you choose the wrong derailleur. I can see that the chain might drag on the bottom of the cage if you used a 63-66 on a 26er. but does this happen in the real world and is it worth concern. any thoughts.


Yeah, front d can hit/rub on cs when suspension cycles in granny.. If it's just a little off you can dremel it down and rotate a bit.


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## Snipe (Mar 6, 2005)

so a 63-66 is the correct choice for a 29er. I would assume that the derailleur is slightly rotated clockwise or the cage is reconfigured to bring the bottom of the cage away from the chainstay . makes sense I guess. I never really looked to see how close the derailleur actually came to the chainstay when in granny.


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## Snipe (Mar 6, 2005)

I have a Kona Satori 29er, running a 24/36/bash. The xt direct mount derailleur is a 66-69 chainstay angle. at the very bottom of the shock compression the chainstay just touchs the derailleur cage. I was going to swap out the crankset and go to a 22/32/bash setup but I have to drop the derailleur a little to accommodate the 32 ring and smaller bash. Then the derailleur is for certain going to hit the chainstay.. With any 3x setup it would be no issue and it would appear that only a 2x with 32 or 34 is a problem with the 66-69 derailleur. I will have to buy a 63-66 derailleur and see what it looks like.


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## FSystem101 (Oct 4, 2018)

I know this is 8years ago post, maybe u already change to single speed system, but I comment for sharing. chain stay angle is important. Chain stay angle related to the frame design. Chain pushing point on fd is related to frame chain stay angle. Using different fd on different frame, will cause changing location of chain pushing point of fd.. and you may face delay downshifting or maybe jerking feeling during upshifting.. of course u can always adjust fd position stopper bolt, but it just not recomended by manual, and may hear chain touching on fd plate after adjusting bolt to meet the shifting performance.. just sharing..


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