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Do I need new front chain rings?

Mikeyboy32Mikeyboy32 Posts: 5
edited October 2010 in MTB beginners
Hi All,

Only just got a bike after 14 years without one and things seem to have moved on quite a bit, so please excuse my poor terminology etc! :)

To briefly sumarise my situation: Nearly two weeks ago I bought a Carrera Subway Ltd from Halfords on a good offer - a shade over £200 (very big money to me ATM). I decided on a hybrid as I am massively unfit/kinda podgy and am going to drop some weight commuting/road riding.

There is a slight noise on the hardest gear (smallest rear/largest front) when under pressure but I am entitled to a free 6 week tune up soon and I have learnt from this site that there is an amount of 'bedding in' to be expected so am not overly worried yet.

What I am in need of advice about is whether the gearing is correct for me. I spend 95% of my time in largest front gear and smallest 2-3 rear gears and am finding times when my little legs could go faster but the gearing does not permit this. At the other end of the scale, the only time I use the smallest front gear and largest rear gears is as I get home so that the bike will be in an easy gear to start again for the next outing. I deal with hills on the middle front gear generally.

I know that the type of bike I have bought is an entry level option so I am not expecting anything mega but it just feels like I could manage a little more if the gearing permitted it.

Any advice would be very warmly welcomed!

Regards,

Mike

PS I live in Worcester if anyone has any routes they might care to share, etc. :)

Posts

  • .blitz.blitz Posts: 6,197
    Some chain rub is to be expected in the big/small combinations but providing it's more of a rustle and not a clatter it will be OK.

    If you are spinning out the biggest gears I suspect you are wearing your undercrackers on the outside and are sensitive to Kryptonite, or maybe the gearing is just too low in which case a larger big ring should suffice. I used to run a 46-tooth big ring on my MTB commuter hack but much bigger than that is getting into road bike territory.

    Welcome to the forum :)
  • shm_ukshm_uk Posts: 683
    According to the Halfords website spec listing for the Carrera Subway Ltd, the bike has a Shimano FC-M311 chainset, in 42-32-22T variety.

    This chainset does not have interchangeable chainrings, so if you wanted to raise the gearing you'll need to buy a new chainset with a bigger outer chainring.

    The bottom bracket on the Carrera is square-taper, which limits your options a bit, however something like this would suit for a direct swap (doesn't matter that it's not Shimano):
    http://www.chainreactioncycles.com/Models.aspx?ModelID=21848


    Of course, unless you have the tools to do it, or know a mate who has, then a bike shop may charge you around £20 to swap a chainset, so it can all get a bit costly... (also involves swapping the pedals over & re-positioning/re-aligning the front mech)




    Just out of interest, I currently run a 46T outer chainring, which just about gives me high enough gearing for commuting on my MTB. Occasionally feel like I could use an extra gear, but not often enough to convince me to swap to a 48T... yet :-)
  • diydiy Posts: 6,473
    how many teeth on the small cog on the rear (cassette) if it not 11, this might be an easier switch.

    sometimes these lower spec 7 speeds don't have an 11T at the bottom but a 12T. This might make a small difference.

    if its not 11t, look at a 11-28T 7 speed rear cassette.
  • shm_ukshm_uk Posts: 683
    diy wrote:
    how many teeth on the small cog on the rear (cassette) if it not 11, this might be an easier switch.

    sometimes these lower spec 7 speeds don't have an 11T at the bottom but a 12T. This might make a small difference.

    if its not 11t, look at a 11-28T 7 speed rear cassette.


    I think the cassette fitted to the Ltd has an 11T smallest sprocket, but if not you could consider fitting one of these:

    http://www.chainreactioncycles.com/Models.aspx?ModelID=40480



    This would give you 1 or 2 extra mph for the same pedal cadence ...

    Speed at 60rpm
    42x12 gearing = 16.2mph
    42x11 gearing = 17.7mph

    Speed at 80rpm
    42x12 gearing = 21.7mph
    42x11 gearing = 23.6mph
  • Hi All,

    Just wanted to say a big THANK YOU for your help, you've given me a few things to think about/save for so I will make the most of this information probably after Christmas.

    diy & shm_uk : yep, it is 11 teeth on the smallest gear at the back, based on the links you've kindly given me this could well be an option as changing the chainset leads to more costs it would seem.

    Anyways, thanks again and happy riding!

    Mike
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