Chainset help 52/36?

Anonymous
Anonymous Posts: 79,667
edited May 2013 in Road general
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:

Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,237
    you can have 50/36... 52/36 I am not aware of
    left the forum March 2023
  • NewTTer
    NewTTer Posts: 463
    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.
  • ugo.santalucia
    ugo.santalucia Posts: 28,237
    Is it?
    I must have been left behind... :-)
    left the forum March 2023
  • Anonymous
    Anonymous Posts: 79,667
    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.
  • ugo.santalucia
    ugo.santalucia Posts: 28,237
    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.
    left the forum March 2023
  • imposter2.0
    imposter2.0 Posts: 12,028
    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
    Calpol Posts: 1,039
    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
  • Anonymous
    Anonymous Posts: 79,667
    edited May 2013
    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?
  • drlodge
    drlodge Posts: 4,826
    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
    drlodge Posts: 4,826
    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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  • Anonymous
    Anonymous Posts: 79,667
    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?
  • drlodge
    drlodge Posts: 4,826
    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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  • Anonymous
    Anonymous Posts: 79,667
    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.
  • drlodge
    drlodge Posts: 4,826
    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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  • Anonymous
    Anonymous Posts: 79,667
    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
  • drlodge
    drlodge Posts: 4,826
    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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  • Anonymous
    Anonymous Posts: 79,667
    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?
  • drlodge
    drlodge Posts: 4,826
    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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  • Anonymous
    Anonymous Posts: 79,667
    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.
  • slowbike
    slowbike Posts: 8,498
    If she loves the bike but you're not sure of the chainset then why not ask the shop if they can change it for a compact to start with...
    If they change it from new then they've still got new rings they can retail.

    What's the worst they can say ..."no" ?!
  • Anonymous
    Anonymous Posts: 79,667
    Good suggestion (I did the same with mine from LBS) but this one is an online discounted bike so its probably more a case of changing stuff myself if need be.

    I have an 11-28 cassette that I only really need for one event, so would actually work out as a bonus to swap as I get an 11-25 (would be great if it was Ultegra too, but not holding my breath) that is more useful too me.

    My chainrings are 50/34 FSA so I could feasibly swap those too, although for the cost, age difference, colour difference, possible weight difference and hassle, its probably not worth it.

    I think she will be fine with 36/28 as a her lowest hill gear. I will just have to live with the fact my wife has a bigger chainset than me :shock:
  • dennisn
    dennisn Posts: 10,601
    Carbonator wrote:
    Guessing I might only have to change the 36 to a 34, or is a 52/34 combo a bit odd?

    52-34 is getting into the realm of maybe your front "D" can do and maybe it can't. Most road front "D's" are listed as 16 tooth difference max. This max is a component companies recommendation that they don't want you to exceed. Saftey reasons and just general workablity reasons. It's their limit. If you exceed it you're on your own. with a 52-34 your at an 18 tooth difference. 2 over most max specifications. I've used a 50-33(17 over) without trouble.