52-34 Chainset

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Joffey

Big Dosser
Location
Yorkshire
Is this possible? I have a 52-36 but want a 34 really. Do I need a compact to change smoothly or can I just shot a 34 on and make do (cheaper option?).
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
You might be able to - what chainset - I'm assuming a newer one as Shimano are doing the sizes in between compact and standard. Depends upon what replacement chain rings are available for the BCD size. That's the limiting factor.
 

Ajax Bay

Guru
Location
East Devon
I think the BCD will be 110 so should be compatible.
An additional challenge is the ability of the FD to deliver a smooth change up with an increased delta (ie from 16t to 18t).
52-36 is a semi-compact. Unless you think you need the 52t (and with a 11t on the rear you probably don't; with a 12t you may not), you can mitigate the risk I've described by just fitting two new rings on: 50 and 34. The FD should not notice the reduction in large chainwheel curvature as much as it'll misbehave with an 18t jump (52-34).
 
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Globalti

Legendary Member
52 - 34 is a drop of eight teeth. Yet my triple is 50/40/30, ten teeth each time and it changes fine.
 

Ajax Bay

Guru
Location
East Devon
my triple is 50/40/30, ten teeth each time and it changes fine.
The triple FDs eg FD-4403 and 5503 are designed to change between middle and outer chainwheels with a gap of 10. So mine is 52-42-30 and is fine. I recently swapped in a 28 small and that was fine too (back to 30 now). The FD doesn't mind so much with the small to middle change.
 
OP
OP
Joffey

Joffey

Big Dosser
Location
Yorkshire
I was worried about the drop too. I might just bite the bullet and get the 105 5800 chainset - it looks nice and shiny and now I have a need for it :-)
 

gavintc

Guru
Location
Southsea
When I researched this a few years ago, the biggest difference that a derailleur could cope with was 16 teeth. I fitted a 50/34 as a result. Things may have changed, but I think you could have some issues.
 
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