Replace derailleur & cassette??

barefootitalian
barefootitalian Posts: 9
edited August 2019 in Cyclocross
Hi all,
So my wife's about to buy a great cx bike (pre-loved).
Great colours too...:-)))
Now: the bike comes with either a DuraAce 50/34 or FSA Gossamer Cross 36/46 Crankset and an 11/28 Shimano 105 cassette, 11-speed.
Short 105 rear derailleur.
We live in a mountainous area and I promised her to find out if the ratio for climbing could be improved.
I'm basically trying to go slightly better than 1:1...

My thoughts so far: get a medium cage derailleur and 11/34 (or even 11/36?) cassette...
Can anyone suggest anything....?
Thanks to all for any feedback!!

Comments

  • joe_totale-2
    joe_totale-2 Posts: 1,333
    How about using the 46-36 and change the smaller chainring for a 30 tooth one?
    Then get the medium cage derailleur and use a 11-34 cassette.
  • Winston Legthigh
    Winston Legthigh Posts: 5
    FWIW I've (hopefully) just bought something with a similar set up - Gossamer Pro 46/36 (the old style, not the abs) on the front and 105 short cage with 11-28 at the back. My plan is to change the inner chain ring to a 34 as they seem to be easy to get hold of, R7000 GS rear derailleur, and a Sunrace 11-36 cassette.
  • barefootitalian
    barefootitalian Posts: 9
    Thanks guys, very informative!
    I'm basically looking for the "less expensive" option....
    :-)))
    @Joe Totale: your one is a good idea. Only : what about when cycling with my roadie friends on the flat or downhill...wouldn't my cycling cadence be too high?

    @Winston Legthigh: similar comment as above on the flat, and easy but maybe not that easy uphill......?
  • Winston Legthigh
    Winston Legthigh Posts: 5
    @barefootitalian: my current bike has 46/30 with an 11-30 cassette. I used to have a 50/34 on the front but wanted lower gearing for off-road. 1-1 is great but there are times when I'd still like a bit lower for some of the really steep off-road stuff, hence I'm looking at 46/34 11-36 on the new bike.
    I was a bit worried that I would miss the top end but that hasn't really been the case. I only ever really ride solo, but on the occasions when I want to crack on (by my standards) along the flat, 40-45km/h is about 100rpm in 46-14, and I generally bottle out before I spin out in 46-11 on descents.

    I played about with different chainring sizes and cassettes on this site http://ritzelrechner.de/ before I went ahead with dropping down to 46.
  • barefootitalian
    barefootitalian Posts: 9
    Hi,
    Thanks for the feedback!
    You really don't even use the 46/11 on the flat...???
    +
    I know about the link you posted but don't have a clue how to use it!
  • Winston Legthigh
    Winston Legthigh Posts: 5
    Yeah - very rarely. I kept a check of what gear I was in today and in a 60km ride I spent about 2~3 minutes in 46-11, and that was on one section of a 4 km downhill. At 105-110 rpm that was 55-60km. On the flat I was mainly in 46-16 and 46-18 which gave me 33-38 km/h at 100rpm. I think in the end the only time I really miss having a bit more on the top end is just to let my legs spin over at a lower cadence on long descents.
  • barefootitalian
    barefootitalian Posts: 9
    Ok,
    Thanks for that!
  • keef66
    keef66 Posts: 13,123
    I have a CX 46/36 chainset on my (9 speed) winter bike and recently fitted a MTB rear mech so I could run an 11-36 cassette. 1:1 lowest gear, and I rarely spin out in 46x11.

    10 speed summer bike has a 50/39/30 triple chainset with an 11-32 cassette / 5701 medium cage RD. Lowest gear a bit lower than 1:1

    I have considered the option of fitting an MTB RD / 36t cassette to this bike to give an insanely low bottom gear
  • barefootitalian
    barefootitalian Posts: 9
    Thanks.
    "...I rarely spin out in 46x11..."
    I often cycle with guys on road bikes and was concerned I would spin out on the flat.
    But you reckons that would be quite unusual, right?
  • whyamihere
    whyamihere Posts: 7,716
    Unless you ride with Tony Martin, you'll be fine with 46-11. It's a slightly higher gear than 50-12, so anyone on a standard compact would have to be in the 11 to have a higher gear.
  • joe_totale-2
    joe_totale-2 Posts: 1,333
    You won't spin out on the flat, it's the downhills where you'll find it a little lacking to bigger gear combos.
  • OlegR
    OlegR Posts: 5
    On my Merida CX, using 50/34 front and 11-36 back, a MTB cassette.
    Using it for:
    CX, Cross Country races, fast road, 200-400km brevets.

    Pretty versatile, but will upgrade, because need a little bit lower for steep climbs and soft, muddy climbs (it works but with knee pain).
    Also I do ride road, and can say that on flat due to our tires, holding a 40km/h speed for longer is kinda limit.
    Similar on descends, on good paved roads, with my 35mm tires, it's difficult to speed up more that 65km/h. And for all of this guess 46 will be enough to ride on flat at 35km/h and down at 55-65km/h at a proper cadence.

    For lower gears, I'll go with 30 front, or will add 40 at the back cassette (if will use 34 front).

    Shortly, to have a versatile CX bike:
    46/30 and 11-34 or 36
    50/34 and 11-40 if need more speed.

    everything work well with 105 rear medium cage derailleur.

    And also I'm thinking at Shimano new GRX groupset.

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