Changing chainrings

Kauto5
Kauto5 Posts: 90
Hi everyone. I'm a novice when it comes to maintenance and repairs other than the very basics so I'm looking for a bit of advice.

I wish to change from semi compact 53/36 to compact 50/34. It's 12 speed 11-30 R8100 - would I need to reduce the length of the chain and adjust both derailleurs?

I'd like to have a go at doing it myself but I'm worried I'd make a complete mess of things. If it was just a case of changing the chainset then I'd be fine doing that with the help of s couple of YouTube videos, but if adjustments are needed then I'll go to my LBS.

Thanks!

Comments

  • pblakeney
    pblakeney Posts: 26,533
    Should simply be a matter of changing the chainset. No real reason for derailleur adjustments but a tweak in worst case. Chain could lose a link but should be okay.
    The above may be fact, or fiction, I may be serious, I may be jesting.
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  • daniel_b
    daniel_b Posts: 11,766
    edited May 2022
    In my opinion, you would likely need to slide the front derailleur down ever so slightly so it's close enough to the 50, and as already mentioned probably trim the chain marginally.

    If you can change a chainset, you can change the chainrings, you just need some allen keys plus the replacement rings, and need to ensure they go on in the right orientation.

    Just compare with the current setup.
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
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  • If you have the time and persistence, you can do the job. But I would do it in the presence of a handyman. I know how to change the wheel and tube, but to get in deeper, I'm afraid of breaking it. It all depends on your time. If you have time, you can spend a whole day just to learn :)
  • trevor.hall12
    trevor.hall12 Posts: 451
    edited May 2022
    Front mech will need shifted down a little and a link out the chain too
    All very simple to do .
    Removing the chainrings is 4 torx bolts .
    When you put new ones on ensure they are torqued up properly and I always put a spot of blue thread locker .
    Once the crank is back on set the FD between 1 to 3 mm from the top of the 50.

  • laurentian
    laurentian Posts: 2,475
    You've probably go this covered but make sure you order the correct BCD on your new chain rings - I've made this mistake . . .
    Wilier Izoard XP
  • imposter2.0
    imposter2.0 Posts: 12,028
    The other alternative (possibly cheaper) would simply be to switch to a wider ratio cassette, assuming you don't have one already. A couple of teeth extra on the rear is going to be far more noticeable from a gearing perspective than a couple of teeth off the front.
  • daniel_b
    daniel_b Posts: 11,766

    I always put a spot of blue thread locker .

    What is the reason for the thread locker, have you had issues previously, or is it an anti creak measure?
    Curious to know what product you use, as I guess you don't want something too stubborn!
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • Munsford0
    Munsford0 Posts: 647
    I tend to use Loctite 243 on mudguard and rack mounting bolts, chainring bolts.

    New chainring bolts will generally come with blue threadlock pre-applied.

    I use copperslip on threaded things which have a tendency to corrode and be a b@stard to undo - BB cups, pedals, brake caliper mounting bolts. From new they also are often supplied with threadlock applied but the copperslip certainly helps with undoing them in years to come
  • trevor.hall12
    trevor.hall12 Posts: 451
    daniel_b said:

    I always put a spot of blue thread locker .

    What is the reason for the thread locker, have you had issues previously, or is it an anti creak measure?
    Curious to know what product you use, as I guess you don't want something too stubborn!
    Blue is the medium strength so not impossible to remove but as its seldom they need removed its good practice .Not that I've had any issues.
  • Kauto5
    Kauto5 Posts: 90
    Many thanks everyone for the replies, much appreciated. I think I'm going to give this a go myself having read through, thanks again!