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Changing from Compact to Semi-Compact what cassette

jpowerjpower Posts: 554
edited November 2016 in Road beginners
hiya needing some advice, because simple gearing ratio is beyond me.

I've been riding compact 50/34 with 12-30 cassette, been abs fine for me. My new bike is coming with a semi compact 52/36 and 12-25 cassette.

Just concerned about the hills in the chilterns as I am a wimp. Currently up to 5-6% climbs I'm on the small ring with about 2 downshifts to spare, there some short burst that get up to 13% where i set on the lowest possible.

I'm wondering if I am going to need 11-28 or 11-32, don't want to look like a plonker walking up the hill :D

Any advice appreciated.

NOTE: It's all 105 setup 11 speed.

Posts

  • Running a 11-32 would depend on the deraileur size I think. Short cage can't handle a cassette like that.
  • AnonymousAnonymous Posts: 79,692
    To be honest (and I know this has been done to death) is that if I were you then I would simply replace the rings on the chainset with a compact again. They can be had quite cheaply online. Annoyingly the outer ring does cost more.

    If you are slow on hills then a compact gives you the ratios you need to get up them comfortably while allowing acceptably close spacing at the rear.

    You may be looking at a 32T rear cassette which may cause shifting issues when in the bottom gear if you rear mech can't handle it (check you have a long cage, or "GS" rear mech) but also quite wide spacing between sprockets which may be a nuisance.

    Also - if the bike is brand new, you may be able to get them swapped for free.
  • jpowerjpower Posts: 554
    Does this help:

    Rear Derailleur - Shimano 105 short cage
    Front Derailleur - Shimano 105 braze-on
    Chainset - Shimano 105 (51cm = 170mm)
    Chainwheel - Shimano 52/36T
    Bottom Bracket - FSA BB30 with 24mm spindle reducers
    Chain - Shimano 11-speed
    Freewheel - Shimano 11-speed, 12-25T

    Bike is a Felt AR5
  • AnonymousAnonymous Posts: 79,692
    You'll need a long cage rear derailleur, a longer chain and then your cassette of choice.

    Personally I would go for compact chainset and your cassette of choice. It'll be lighter too ;)
  • jpowerjpower Posts: 554
    Thats a lot of change for a new bike. Question I believe I can use an 11-28 without having to change anything, what I wondered was my previous easy gear 34*30 on a

    36*25
    36*28

    what would that be equiv on my earlier compact setup, how gear from easy would i have to go up to feel the same.

    Not even sure if that is a sensible question :-)
  • Alex99Alex99 Posts: 1,407
    jpower wrote:
    Thats a lot of change for a new bike. Question I believe I can use an 11-28 without having to change anything, what I wondered was my previous easy gear 34*30 on a

    36*25
    36*28

    what would that be equiv on my earlier compact setup, how gear from easy would i have to go up to feel the same.

    Not even sure if that is a sensible question :-)

    36/28 = 1.29 ratio

    34/1.29 = 26.4 (so roughly, 26 sprocket on your old one)

    Only you can decide. Unused kit sells well second hand. That would offset the expense of new rings.
  • jpowerjpower Posts: 554
    Honestly I'm trying. So I think the above is saying it will feel like 34/26 in current setup. Got details of the existing cassette:

    12-30T: 12, 13, 14, 15, 17, 19, 21, 24, 27, 30

    so it sounds like 36/28 would feel like my current easiest + 1 upshift. I think this I could handle if my understanding is correct. Using the above method:

    36/25 = 1.44 ratio
    34/1.44 = 23.61 (so roughly, 24 sprocket on your old one)

    so 36/25 would feel like my current easiest + 2 upshifts

    If the above is correct, looks like on anything going above 8% and if its long may spell trouble.

    I think i could getaway with 11-28 assuming the above calculations.
  • Alex99Alex99 Posts: 1,407
    jpower wrote:
    Honestly I'm trying. So I think the above is saying it will feel like 34/26 in current setup. Got details of the existing cassette:

    12-30T: 12, 13, 14, 15, 17, 19, 21, 24, 27, 30

    so it sounds like 36/28 would feel like my current easiest + 1 upshift. I think this I could handle if my understanding is correct. Using the above method:

    36/25 = 1.44 ratio
    34/1.44 = 23.61 (so roughly, 24 sprocket on your old one)

    so 36/25 would feel like my current easiest + 2 upshifts

    If the above is correct, looks like on anything going above 8% and if its long may spell trouble.

    I think i could getaway with 11-28 assuming the above calculations.

    Yes, that's about right. In the end, if you don't like it, you would probably find someone on here that would do a straight swap with you for the chainrings.
  • AnonymousAnonymous Posts: 79,692
    I would, but I have many miles on my ones.
  • jpowerjpower Posts: 554
    Cool, thank you, i'll see if the shop will swap 12-25 for 11-28 and take it from there.
  • If you want the same ratio as 34/30 then you'd need to go 36/32.
  • Here's the best gear calculator i've come across:-

    http://www.gear-calculator.com

    click on the 'compare two setups' and you can easily play around, once you've setup the gear and cassette ratios - up to you whether you want to see gear-inches if that floats your boat rather than km/hr etc.

    If you went to a long/medium rear cage you could use a 11-32 cassette... and Edco do a lightweight monoblock one for a price, and it has slightly different gear gapping to the Shimano 11-32.

    http://www.edco-wheels.co.uk/product/mo ... cassettes/


    Edco 11-32 = 11, 12, 13, 14, 15, 16, 18, 21, 24, 28, 32

    vs

    Shimano = 11, 12, 13, 14, 16, 18, 20, 22, 25, 28, 32
  • AnonymousAnonymous Posts: 79,692
    edited November 2016
    Why did you buy a semi compact Aero Felt AR5 if you want really low gearing?

    I have a very similar bike (aero road 52/36 11-25) and have to admit to upping (OK, lowering :( ) the 11-25 to 11-28.
    I mainly did it as wife's new bike had exactly the same groupset apart from being 11-28, and as she does not need the 28, I swapped them over.

    Go to 11-28 max or get a different bike IMO.

    Do you still have your old bike?
    I have a compact bike for use when I know it will be hilly, but am happy that I would not be walking on 36/28 as a lowest gear if I got stuck.

    Your new bike should be enjoyed as it is (or with slight cassette change) on faster/flatter rides.
    It will look plain wrong with a compact chainset and/or huge MTB cassette.
  • AnonymousAnonymous Posts: 79,692
    You could swap it for the 2017 E bike version. The Felt AR5E :twisted:
  • fat daddyfat daddy Posts: 2,605
    Carbonator wrote:
    The Felt AR5E :twisted:


    mwuh huh haaaa :mrgreen:
  • jpowerjpower Posts: 554
    Carbonator wrote:
    You could swap it for the 2017 E bike version. The Felt AR5E :twisted:
    I'm sure we done this already :D
  • jpowerjpower Posts: 554
    Carbonator wrote:
    Why did you buy a semi compact Aero Felt AR5 if you want really low gearing?

    I have a very similar bike (aero road 52/36 11-25) and have to admit to upping (OK, lowering :( ) the 11-25 to 11-28.
    I mainly did it as wife's new bike had exactly the same groupset apart from being 11-28, and as she does not need the 28, I swapped them over.

    Go to 11-28 max or get a different bike IMO.

    Do you still have your old bike?
    I have a compact bike for use when I know it will be hilly, but am happy that I would not be walking on 36/28 as a lowest gear if I got stuck.

    Your new bike should be enjoyed as it is (or with slight cassette change) on faster/flatter rides.
    It will look plain wrong with a compact chainset and/or huge MTB cassette.
    I have no plans of changing it to a compact, just the best cassette choice for me will do.

    I bought the AR5 because I love the way it looks, once the aero rims go on (and to stop me pining at other bikes), and my first bike was much more a great starter/leisure geometry bike my riding has improved a lot and it's time to step up to something more aggressive. Oh did I mention I love the looks :D

    So n+1 does not work in my house, there no way I will be able to keep it. In truth if I had an n+1 it would most likely be a cheap non-carbon for the winter may look second hand when she forgets I bought this one.

    Wheels arriving today, bike not sure of date yet.
  • Mad_MalxMad_Malx Posts: 4,119
    jpower wrote:
    Cool, thank you, i'll see if the shop will swap 12-25 for 11-28 and take it from there.

    You will never use the big gears - 52x11 is huge, and how often do you spin out at your existing 50x12?
    So you are down to a 9 speed block, with wider gaps in the middle than need be.
  • jpowerjpower Posts: 554
    Mad_Malx wrote:
    jpower wrote:
    Cool, thank you, i'll see if the shop will swap 12-25 for 11-28 and take it from there.

    You will never use the big gears - 52x11 is huge, and how often do you spin out at your existing 50x12?
    So you are down to a 9 speed block, with wider gaps in the middle than need be.
    Never spin out in 50x12 only possible for me on downhill, however by that point I would not be pedalling on open road to try and go any faster.
  • jpowerjpower Posts: 554
    coops1967 wrote:
    Here's the best gear calculator i've come across:-

    http://www.gear-calculator.com

    click on the 'compare two setups' and you can easily play around, once you've setup the gear and cassette ratios - up to you whether you want to see gear-inches if that floats your boat rather than km/hr etc.

    If you went to a long/medium rear cage you could use a 11-32 cassette... and Edco do a lightweight monoblock one for a price, and it has slightly different gear gapping to the Shimano 11-32.

    http://www.edco-wheels.co.uk/product/mo ... cassettes/


    Edco 11-32 = 11, 12, 13, 14, 15, 16, 18, 21, 24, 28, 32

    vs

    Shimano = 11, 12, 13, 14, 16, 18, 20, 22, 25, 28, 32

    That is a great site, THANKS. In my few minutes of boredom, created me some comparisons:

    12-30%20vs%2012-25.jpg
    12-30%20vs%2011-28.jpg
    12-25%20vs%2011-28.jpg
  • jpowerjpower Posts: 554
    On pictures verdict is 11-28 will get me pretty close to that easy gear for the worse climbs, but I will lose the nice close gearing of the 12-25 in the big ring. Which is a damn shame really as majority of the time is spent in that big ring, maybe just need to make them legs stronger :-)
  • jpower wrote:
    maybe just need to make them legs stronger :-)

    Or improve your cardio fitness
    I'm sorry you don't believe in miracles
  • jpower wrote:
    On pictures verdict is 11-28 will get me pretty close to that easy gear for the worse climbs, but I will lose the nice close gearing of the 12-25 in the big ring. Which is a damn shame really as majority of the time is spent in that big ring, maybe just need to make them legs stronger :-)


    Did you notice some of the other Edco options.... :lol:

    11 - 27 ( 11 to 17 in single tooth steps - so you get your 16 tooth back, then 19, 21,24,27) as well as the 11-28, oh - and a 12-27 option to tempt you further :P
  • jpowerjpower Posts: 554
    Yeah saw them, really don't want to making all those changes. Guess good to know there are options. I'll be working hard to make 11-28 work for me.
  • jpowerjpower Posts: 554
    New baby part 1 is here:

    C2D38DEE-FC38-42D3-AC97-27EBA4FF6759.jpg
  • svettysvetty Posts: 1,904
    jpower wrote:
    Yeah saw them, really don't want to making all those changes. Guess good to know there are options. I'll be working hard to make 11-28 work for me.

    Which is the - IMO - correct answer.....
    FFS! Harden up and grow a pair :D
  • Rule #5 it, you'll be surprised how soon the bigger gearing will be fine.
  • Thumbs up for the new wheels - particularly the complete absence of gross advertising. What are they?
  • jpowerjpower Posts: 554
    coops1967 wrote:
    Thumbs up for the new wheels - particularly the complete absence of gross advertising. What are they?
    I plan to take warning label off too :-) they are from wheelsmiths aero 50 hand built weighed in at 1.5kg :-). I should have a bike on Monday for them to go onto.

    Only shame is no n+1 so the new toy going to have to face winter, other half says why get an expensive bike if your only going to use it on nice days, we live in England remember... fun conversation
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