Chainset help 52/36?

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Carbonator
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Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 11:18 am

Am looking to get the mrs a road bike and have been looking at compacts, so 50/34 12-25 or 12-28.

She is pretty good with hills both running and it seems cycling too, so I thought this would be fine and just up the cassette by one if need be.

Have seen a bike with 52\36 11-25 which has left me with a few questions that I hope you guys can help with :D

Is that technically a double? How would it compare with a 50\34 (standard compact?) and a 53/39 (standard double?)?

Which is a lower gear, 34 chainring\25 sprocket or 36 chainring\28 sprocket?

Can most cages (its Ultegra) cope with going up from 25 to 28 ?

Are the chainrings on the chainset fully interchangeable? So that if I got the same FSA ones in a 50 and 34 I could just swap them over, or would the whole chainset have to be swapped?

Is it easy to swap chainrings or does the chainset have to come off anyway?

I am thinking of getting the bike and seeing how she gets on with it, then possibly changing the cassette to a 28 and/or the chainrings to 50\34 or similar.

Thanks for any help you can give :wink:

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ugo.santalucia
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Re: Chainset help 52/36?

Postby ugo.santalucia » Wed May 22, 2013 11:20 am

you can have 50/36... 52/36 I am not aware of

NewTTer
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Re: Chainset help 52/36?

Postby NewTTer » Wed May 22, 2013 11:25 am

52-36 is very common.

OP yes chain rings are interchangeable providing they are the same BCD (bolt centre diameter) and you can just unbolt the chainrings from the bike to change them. As for making comparisons look up an online gear inch calculator and you can compare the differing ratios.

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ugo.santalucia
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Re: Chainset help 52/36?

Postby ugo.santalucia » Wed May 22, 2013 11:30 am

Is it?
I must have been left behind... :-)

Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 11:36 am

Cheers TTer.
How would I know if BCD (other than contacting FSA) is the same? It is FSA Energy BB30.
Is 52\36 classed as a compact or double? I was hoping it was more a big compact than a small double so that the BCD was more likely to be the same lol.

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ugo.santalucia
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Re: Chainset help 52/36?

Postby ugo.santalucia » Wed May 22, 2013 11:39 am

Carbonator wrote:Cheers TTer.
How would I know if BCD (other than contacting FSA) is the same? It is FSA Energy BB30.
Is 52\36 classed as a compact or double? I was hoping it was more a big compact than a small double so that the BCD was more likely to be the same lol.


36 has to be compact... the smallest possible ring you can fit to a double is 38.

Imposter
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Re: Chainset help 52/36?

Postby Imposter » Wed May 22, 2013 11:45 am

Carbonator wrote:Cheers TTer.
How would I know if BCD (other than contacting FSA) is the same? It is FSA Energy BB30.
Is 52\36 classed as a compact or double? I was hoping it was more a big compact than a small double so that the BCD was more likely to be the same lol.


What defines a compact crank is not the gearing, but the BCD. Compact chainsets have a 110mm BCD. So any ring with a 110BCD will fit the compact crank spider. The final gearing you select is up to you.

Calpol
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Re: Chainset help 52/36?

Postby Calpol » Wed May 22, 2013 11:47 am

ugo.santalucia wrote:
Carbonator wrote:Cheers TTer.
How would I know if BCD (other than contacting FSA) is the same? It is FSA Energy BB30.
Is 52\36 classed as a compact or double? I was hoping it was more a big compact than a small double so that the BCD was more likely to be the same lol.


36 has to be compact... the smallest possible ring you can fit to a double is 38.

i read the other day that Dave Millar has 52/36 on his Cervelo. Halfway down the page

http://road.cc/content/news/84206-giro-tech-2013-team-skys-pinarellos-lotto-bellisol-ridleys-and-garmin-cerv%C3%A9lo

Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 11:51 am

Cheers guys, really appreciate all the help ;-)

The calculator I used gave 2.7 (inches?) for 36/28 and 2.8 for 34/25.
Am I right in thinking that makes the 36/28 a marginally lower gear?
If so then sticking on a 28 will bring it back to the same as a standard 34/25 set up for hills.

If the 36 has to be a compact then that would be a cheap and easy swap too.
Guessing I might only have to change the 36 to a 34, or is a 52/34 combo a bit odd?
Last edited by Carbonator on Wed May 22, 2013 11:52 am, edited 1 time in total.

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drlodge
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Re: Chainset help 52/36?

Postby drlodge » Wed May 22, 2013 11:51 am

Carbonator wrote:Which is a lower gear, 34 chainring\25 sprocket or 36 chainring\28 sprocket?


Its just a question of ratios

34/25 = 1.36 (*27 to give 36.7 gear inches)
36/28 = 1.29 (*27 to give 34 gear inches)

So the 36/28 is a lower gear

If you want the lowest gear from your combinations, then 34/28 is it.
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drlodge
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Re: Chainset help 52/36?

Postby drlodge » Wed May 22, 2013 11:54 am

Carbonator wrote:Guessing I might only have to change the 36 to a 34, or is a 52/34 combo a bit odd?


Yes it is odd, in that you'll need a higher capacity rear derailleur due to the larger "gap" between 34 and 52

A 50/34 chainset with 12-28 cassette is fairly common.
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Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 12:01 pm

Cheers driodge,

Why would the deraillier need to be different because of the gap? because of chain length?

Would it be a different Ultegra derailleur on a 52\36 set up to a 50\34 one then?

Could I just change both (to 50 and 34) and take a link out of chain?

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drlodge
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Re: Chainset help 52/36?

Postby drlodge » Wed May 22, 2013 12:14 pm

The capacity of the rear derailleur depends on the difference between the two extreme gears e.g. for a 50/34 chainset and 12-28 cassette:

(50+28) - (34+12) = 32

A 52/36 chainset will give the same answer but a 52/34 combo gives 34. The higher this number, the longer the cage will need to be. Most short cage derailleurs should handle 50/34 with 12/28. Sticking with 50/34 just makes life easier.
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Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 12:34 pm

Cheer, think I got that. If I change the chainrings, I will do both ;-)
I can see from the pic that they are 110 BCD so that makes that do able.

So to confirm, is this all feasible without affecting the derailleur?

1/ I get the bike and she has no problem with 36/25 as lowest gear
2/ I change the cassette from 11-25 to 11-28.
3/ I change from 52\36 11-25 to either 50\34 11-25 or 50\34 11-28.

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drlodge
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Re: Chainset help 52/36?

Postby drlodge » Wed May 22, 2013 12:38 pm

Carbonator wrote:Cheer, think I got that. If I change the chainrings, I will do both ;-)
I can see from the pic that they are 110 BCD so that makes that do able.

So to confirm, is this all feasible without affecting the derailleur?

1/ I get the bike and she has no problem with 36/25 as lowest gear
2/ I change the cassette from 11-25 to 11-28.
3/ I change from 52\36 11-25 to either 50\34 11-25 or 50\34 11-28.


That is probably all doable, but no guarantee that the RD will have enough capacity - it should, but no guarantee.

BUT, if she has no problem with 36/25 as the lowest gear, why change anything at all? Moving to a 34 chainring or 28 sprocket will make the gear even lower.
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Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 12:44 pm

I would not change if option 1 worked. 2 and 3 were back up plans.

Using your method of adding up gears the gearing the bike comes with = 30

(52+25)-(36+11)=30

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drlodge
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Re: Chainset help 52/36?

Postby drlodge » Wed May 22, 2013 12:48 pm

SO:
Do (1) first. If gearing not low enough do (2). If still not low enough you should be able to check if the RD can take a little more chain slack and then consider doing (3). You'll probably need to remove 1 full link from the chain for (3)

A cassette is probably cheaper than a new chainring.
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Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 13:00 pm

Thanks ;-)
I do not mind changing stuff except the derailleur.
Last question, do you think it would be the same size Ultegra derailleur on the 52/36 11-25 bike as a 50/34 12-25 one?

Oh, and what hits what if the cage is too short? top jockey wheel on cassette?

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drlodge
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Re: Chainset help 52/36?

Postby drlodge » Wed May 22, 2013 13:08 pm

If the bikes are essentially the same then its likely to be the same RD e.g. tiagra or whatever. But without knowing the bikes I can't say.

If the cage is too short, then it won't be able to take up all the slack (small-small) and/or chain will be too short for large-large.
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Carbonator
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Re: Chainset help 52/36?

Postby Carbonator » Wed May 22, 2013 13:17 pm

Thanks again.
I'll see if she likes the bike (thinking she will love it was the reason for the thread) and will go over the figures again if she does.
Such a shame its not a standard compact.


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