Forum home› Road cycling forum› Road beginners

Changing rear cassettes

SV GarySV Gary Posts: 21
edited March 2012 in Road beginners
Hi There

I am pretty new to cycling and have a 2010 Specialized Secteur Elite with a 10 speed Shimano Tiagra 12-27t rear cassette. I am looking to do some hill climbs and really want to get some lower gears. So the question is can I replace my Shimano Tiagra 12-27t with a Shimano Tiagra 12-30t - are they direct replacements? Will I need to do anything with the de-railleur?

Any advice welcome.

Posts

  • keef66keef66 Posts: 13,123
    I think your rear mech has a max capacity of 28T in theory, although you might be lucky and get it to work with 30T.
  • styxdstyxd Posts: 3,234
    Your bike has a triple chainset. If you cant climb hills with a 30/27 then your censored useless!
  • John.TJohn.T Posts: 3,698
    If your rear mech is the current RD4600 model then it will take the 30 sprocket. You may need a longer chain though.
    My Fleet.
  • SV GarySV Gary Posts: 21
    Keef66/John T- My rear de-railleur is not the RD4600 and hence i think I am limited to 28T and will therefore need to upgrade the derailleur - thanks for the advice

    Styxd - I am cycling to keep fit and not to race, the hill I am looking to do is the 25% Mow Cop as part of the Cheshire Cat sportive next March and at 100+kgs I am going to find that a challenge! - thanks for the helpful comments - you know how to make a newbie to Bikeradar welcome!
  • keef66keef66 Posts: 13,123
    So what RD do you have??
  • SV GarySV Gary Posts: 21
    Shimano 105
  • styxdstyxd Posts: 3,234
    you know how to make a newbie to Bikeradar welcome!

    I try my best! :lol:

    But you've got till next March, thats 4 months to lose 20kg or so. That would be a better option than a new mech and cassette, and it'll cost you nowt.
  • SV GarySV Gary Posts: 21
    10kg is the plan!
  • MattC59MattC59 Posts: 5,433
    SV Gary wrote:
    Styxd - thanks for the helpful comments - you know how to make a newbie to Bikeradar welcome!

    SVGary, I wouldn't worry about Styxd, there are some ignorant pr*cks on here. They're generally the ones full of BS and with a low post count. Judging from his post and the 1.5 posts per week, I'd say he fits nicely into this category.
    Science adjusts it’s beliefs based on what’s observed.
    Faith is the denial of observation so that Belief can be preserved
  • styxdstyxd Posts: 3,234
    10kg is the plan!

    No bother!

    Dont go mad though, you want to enjoy your christmas dinner.
  • deswahriffdeswahriff Posts: 310
    Hey Gary..read that sticky at the top " I need smaller gears..." its a bit of a slog, but well worth it! ...so much helpful stuff there, sorted me out just fine!
    Black and orange one,
    Red one,
    Black one.
  • SV GarySV Gary Posts: 21
    Yes read that thread - ordered Shimano 105 10 sp 11-28 chainset to replace 12-27 - should help a little and should be interchangeable without need for alterantive DR - then just got to shed some weight - Looks like I am going to do the Tour of the Peak as well now in May - 3 peaks in one day - must be mad, only done Hartside to date as part of C2C.
  • BobbinogsBobbinogs Posts: 4,841
    I also have the Spesh Secteur but I honestly don't think anyone will be able to feel a difference between a 27 and a 28 whatever bike you ride. I also think that you may find anything lower than 30/27 (or 28) will not be great as the gearing will be so low that momentum may be a problem and, if the surface is a bit damp, the very high leverage could mean the back wheel spins a lot as you put the power down.

    You will find that the gears you need go up a notch or two as you get bike fit (I now run an 11-25 on the Spesh and can get up any decent steep slopes but I do have more of a climbing build than your 100kg). On some of my training rides I also move the low stop to prevent me going to the bottom gears just to force me to improve my climbing technique. which is pretty important (as in backing off the pressure, getting the right gear for the rhythm, relaxing and then patiently working towards the top).

    It is nice though to have a lower gear when you need it (I always end up shifting down at ~80-90 miles on a hilly ride) but you will surprise yourself how your training effort can be so tangibly rewarding. Keep at it :)
  • BrianTrousersBrianTrousers Posts: 218
    SVGary, I wouldn't worry about Styxd, there are some ignorant pr*cks on here. They're generally the ones full of BS and with a low post count. Judging from his post and the 1.5 posts per week, I'd say he fits nicely into this category.

    I have a low post count. I've tried everything and there's nothing to be done. It has caused a great deal of difficulty in my marriage. Please don't mock the afflicted.
  • ErudinErudin Posts: 136
    You can also lower gearing by changing the inner chainring. On my audax/tourer bike I changed the 30t inner to a 26t (Shimano Tiagra FC-4503 Chainset). The inner chainring I fitted was a Stronglight 5 Arm 74mm Road Chainring.

    Link: Front Shifting

    "Inner chainring size: If you've followed the development of front mechs described above, you'll realise that inner chainrings can be made almost as small as you like. It hardly matters."
  • SV GarySV Gary Posts: 21
    So with a sprocket change (11-28 replacing 12-27) and a 5kg weight reduction and a hill climb training program, I completed the 76mile 'Cheshire Cat' yesterday without stopping in 5hrs 30min dead including Mow Cop!

    Bring on the Tour of the Peaks - would'nt mind some feedabck of the degree of difficulty of the 'Tour of the Peaks' versus the 'Cheshire Cat'

    Cheers

    Gary
  • rpd_steverpd_steve Posts: 361
    not done the 3 peaks but well done on your ride! No doubt there will be some sod come along who says 'i did it in 24 mins...', but given the chalange you set youself and the improvement youve made it sounds like you desirve a night in the pub.
  • keef66keef66 Posts: 13,123
    Well done that man!

    And the 3 Peaks is an entirely different beast from the Tour of the Peaks! Well worth not confusing those two :D
  • SV GarySV Gary Posts: 21
    Thanks for the comments

    The Kilo to Go 'Tour of the Peaks' includes Cat and Fiddle, Winnats and Holme Moss passes
  • keef66keef66 Posts: 13,123
    But not Pen-y-Ghent, Whernside or Ingleborough!
  • BobbinogsBobbinogs Posts: 4,841
    tbh, and in reference to my earlier post, I am still struggling to understand how changing from a 12-27 to an 11-28 would help (or did help) your climbing but the main point is "well done". Nothing beats the inner pride of meeting a challenge so onwards and upwards (literally).
Sign In or Register to comment.