Replacing worn chainset - just the rings, or the whole crankset?

Secteur
Secteur Posts: 1,971
edited May 2016 in Workshop
Not my photo, but I have this on my Cannondale Synapse (SI crankset).

s-l300.jpg

The chainrings are starting to get worn, and I want to replace them.

Do I just need to replace just the chainrings, or should I really be replacing the whole thing including crankarms, axle etc etc

This may be a moot point as it seems quite a challenge to find just the chainrings online (and even the full crankset is relatively hard to find, though I suspect my LBS could order it, albeit at full RRP with it being a special order).

Thanks!

Comments

  • jrich
    jrich Posts: 278
    You just need to replace the rings as they are the part that has worn. Any chainrings will do so long as the BCD is the same. In the photo you have posted the chainset has FSA rings fitted, not cannondale, and they should be widely available.
  • Secteur
    Secteur Posts: 1,971
    Yes, you're quite right - I hadn't realised / clicked that they're FSA - that should make my searching for replacements much easier!

    Thanks.
  • Secteur
    Secteur Posts: 1,971
    Another question...

    I currently have 50/34 compact with 11-32 but never use the 3 biggest cogs on the cassette, though I do sometimes feel I wished I had a bigger gear than 50.

    If I kept my 11-32 cassette (I like knowing I have a bail out gear as it's VERY hilly where I ride) but went to a 52/36 semi compact, am I right in thinking I'd just need a slightly longer chain and a small adjustment to the vertical position of the front derailleur? Would it otherwise be entirely compatible to do this?

    It would mean I'd have the bigger 52-11 gear, and I'd probably start using those big three cogs on the cassette more if I went from 34 to 36 on the front.

    PS do 50/34 and 52/36 use the same 110mm bolt diameter? If the 52/36 is in fact a 130mm standard (like standard 54/39 doubles) then it becomes too much of a faff to be worth it for me.

    Many thanks!
  • jrich
    jrich Posts: 278
    52/36 would be fine as the BCD is the same as with 50/34 - both are 110. (53/39 would not work because that is 130 BCD). BTW Praxis Works make excellent chainrings: https://www.praxiscycles.com/road-cyclocross/
    You can find cheaper options about (like the FSA rings) but Praxis will be second to none in terms of performance.

    And yes, you would just need a slightly longer chain. Although if the chainrings are worn then it's likley that the whole drive train is worn and you will therefore be best off installing a new chain and cassette at the same time as the chainrings in order to maximise the lifespan of the new rings. If you were to install new chainrings with a worn chain/cassette then you will end up wearing out the new chainrings very quickly!! Really it depends how many miles you have put into the chain/cassette. At the very least though I'd be buying a new chain along with the new rings. It would be a good idea to measure your chain and see how stretched it is as that will indicate if the cassette might need replacing too.
  • Secteur
    Secteur Posts: 1,971
    Brilliant, thanks!

    I replace my chain & cassette roughly every year, and have actually just ordered new ones but won't fit till I sort out what I"m doing with these chainrings!

    Thanks for,your excellent and helpful reply!
  • Secteur
    Secteur Posts: 1,971
    Hi there,

    Well as per your suggestion, I just bought the praxis chainring, but I just have a question - will I simply use the same existing chainring bolts, or will I need special new ones?

    The Cannondale SI crank spider seems to use these "no nuts" bolts - not the usual male/female bolt sets you usually see:
    [img][/img]http://www.cannondale-parts.de/WebRoot/ ... CN6327.JPG

    I can't seem to fathom if the bolts are spider-specific (In which case I'm fine) or chainring specific (in which case I may need those standard male/female bolts)

    Can you help shed any light on this?!

    Cheers
  • Secteur
    Secteur Posts: 1,971
    edited May 2016
    Well, an update (though I suspect no one is interested at this point!)

    I bought the Praxis rings suggested above, and after significant research it all seemed compatible.

    Well, they aren't, and they don't work with the Cannondale SI spider, at least not the one that came with my 2014 Synapse Hi-Mod.

    The Praxis rings do look awesome though, even if they dont work!
  • keef66
    keef66 Posts: 13,123
    Won't the retailer take them back? Or have you marked them when trying to get them to fit??
    Last resort you can sell them in the classifieds on here.
  • keef66
    keef66 Posts: 13,123
    http://www.chainreactioncycles.com/fsa- ... prod129960

    http://www.chainreactioncycles.com/fsa- ... prod129956

    Any use?? Or are those the ones you refer to?
  • Secteur
    Secteur Posts: 1,971
    edited May 2016
    keef66 wrote:
    Won't the retailer take them back? Or have you marked them when trying to get them to fit??
    Last resort you can sell them in the classifieds on here.

    Not marked, and thankfully after contacting the retailer they offered a refund without any fuss, phew!
  • itboffin
    itboffin Posts: 20,064
    Buy a shimano 105 crankset either 5700 or 5800 and fit the praxis rings
    Rule #5 // Harden The Feck Up.
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
    Rule #12 // The correct number of bikes to own is n+1.
    Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.
  • Secteur
    Secteur Posts: 1,971
    itboffin wrote:
    Buy a shimano 105 crankset either 5700 or 5800 and fit the praxis rings

    That would be going backwards compatibility-wise!

    All sorted now via my outstanding LBS!

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