Bicycle Mechanics - Shimano 105 rear derailleur max cog?

Hi, guys

I have a 105 7-speed rear derailleur, model rd-1055. I believe the Shimano spec for this part says the max cog it can take is 27. However, I may want to cheat a bit with it and use it with a 28-tooth max cog. Is this possible? Is there anything special I would need to do in order to accomplish this?

Thanks!

Hi, guys

I have a 105 7-speed rear derailleur, model rd-1055. I believe the Shimano spec for this part says the max cog it can take is 27. However, I may want to cheat a bit with it and use it with a 28-tooth max cog. Is this possible? Is there anything special I would need to do in order to accomplish this?

Thanks!Actually,the spec was 28(there was no 27 in 7 speed 105 days) and it will likely handle more like the current stuff.Adjust the B tension screw.

Actually,the spec was 28(there was no 27 in 7 speed 105 days) and it will likely handle more like the current stuff.Adjust the B tension screw.

Fantastic. Thanks!

Hi, guys

I have a 105 7-speed rear derailleur, model rd-1055. I believe the Shimano spec for this part says the max cog it can take is 27. However, I may want to cheat a bit with it and use it with a 28-tooth max cog. Is this possible? Is there anything special I would need to do in order to accomplish this?

No problem. Generally these will handle up to about a 30 tooth, unless your frame has a non-standard dropout hanger.

See: http://sheldonbrown.com/capacity for a detailed explanation.

Sheldon "Not By The Book" Brown

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| Always listen to the experts. |
| They'll tell you what can't be done, and why. |
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I'll agree with the above that a 28 works without problem. I haven't tired it myself, and sheldon certainly knows more than I, but I'd say 30 would be a mighty tight fit judging by the clearance on my 105 rear and the 28 tooth.