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  • 105 5800 chainrings 36 to 34T
  • Premier Icon Saccades
    Free Member

    Got rid of a compact SRAM rival11 chainset and replaced it with a semi compact 105 5800 chainset as I hated GXP BB lifespan (or lack of).

    I’m about to do a hilly sportive kind of similar to the Fred Whitton and as I’m ~16 stone I am worried about the climbs, especially towards the end.

    Can I just change the 36t granny for a 34t? It’s the same BCD (110) and will give me a quick and cheap option for just this event?

    I can’t change the cassette without changing the derailuer.

    Premier Icon cynic-al
    Full Member

    Yes but it won’t make much difference.

    Premier Icon mikewsmith
    Free Member

    http://www.hopetech.com/products/drivetrain/bottom-bracket/

    one of these fit? Save the crankset fix the BB

    Premier Icon Saccades
    Free Member

    That link just defaults to the hope home page, but as it’s hope I am guessing it’s more than the thirteen quid from Merlin for a new ring?

    About 6 % difference which is about 2/3 of a gear.

    Premier Icon mikewsmith
    Free Member

    ah didn’t see you had already bought the cahinset

    Premier Icon Saccades
    Free Member

    No worries, thanks for the idea for future reference.

    Premier Icon n0b0dy0ftheg0at
    Free Member

    http://sheldonbrown.com/gear-calc.html say the gear inches for a 28T sprocket will change from 34.7 to 32.8, not even the equivalent of half a gear compared to having a 32T sprocket (where difference would be 30.4 to 28.7) with a 700x32mm tyre.

    Premier Icon ghostlymachine
    Free Member

    Front mech might not like the extra drop, even 50/34 struggles with some set ups. Depending on the mech of course.

    I can’t change the cassette without changing the derailleur.

    You absolutely positive. i.e. because of what the manufacturer says, or because theirs physically no room?

    Premier Icon joemmo
    Free Member

    problem is if you fit a bigger cassette then you may also need a longer chain and / or a smaller front outer ring – and or a larger capacity rear mech…

    Which rear mech and cassette do you have currently? You can usually get 2-4 more teeth than the recommended max sprocket size out of it so cheap cassette + a chain might be your best option.

    You can also get cheaper versions of that wolf-tooth adapter on ebay for a few pounds – search for ‘derailleur hanger extender’ but check where its coming from. I ordered one and it came from china so not an instant fix.

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