I bought a bike recently that has a 34 front 28 rear gear ratio. It is an Elfama E2500, which is a Korean brand I believe. It has a Shimano Claris (which is rated for up to 32 teeth) rear derailleur and an 8 speed 11-28 cassette in the back.

I would like to go with as big of a gear as possible for climbing, somethine like 11-32 which is the biggest I can find in an 8 speed. Something like this... http://goo.gl/eLbluH

Will this fit? Is there some other variable I am missing? Would it be possible to go up to a 10 speed cassette without changing too much on the bike?

  • 1
    If the rear derailer is rated for 32 teeth then you should be able to install a cassette with 32 teeth max with little difficulty. In addition to adjusting the derailer, you will likely need to lengthen the chain (so may as well install a new chain when you change out the cassette -- something that is wise to do in any case). Changing to a 10-speed is not a good idea. Aug 4 '16 at 11:43
  • You should tell us what the chainrings are (probably the whole crankset would need changing). A smaller chainring might be a good or better option.
    – Chris H
    Aug 12 '16 at 16:22

Changing to 10 speed gets real expensive real quick, because you need new chain, cassette, shifter at a minimum.

32 tooth is 4 more than 28, so its a ~14.3% increase. That's quite a lot - you will need extra chain links, and your rear derailleur will need adjusting and may not work with the extra teeth. It's hard to be sure without trying it.

Your other possible change is to shrink the smallest of your front chainrings. This may mean slower changes between rings, or the FD may not have enough capacity. You'll also need a medium or long cage rear derailleur to help take up the difference in chain length.

Final option is to grin and bear it. Climbs up hills aren't fun. They're supposed to be a workout.

  • 1
    Thanks for the answer, how about adding the 11-32 cassette instead of the 11-28 I have? Should this be doable with the gear that is already on the bike?
    – Joff
    Aug 4 '16 at 10:22
  • Thanks for the edit. What would need to be adjusted on the derailleur? Would it just be an adjustment to the screws that control its range?
    – Joff
    Aug 4 '16 at 10:41
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    Penultimate sentence is wrong ;)
    – alex
    Aug 4 '16 at 11:45
  • 1
    Yeah, best bet for an easy conversion is buy a new chain and new cassette and install them. You'll want a new chain so you can size it for the larger rear cogs. You may need to adjust the derailleur a bit, possibly dialing in the b-screw for clearance of the larger cassette cogs and adjusting the upper limit screw to be sure you don't throw your chain behind your cassette.
    – Benzo
    Aug 4 '16 at 13:54

The chances are this is an alloy bike. Cold setting is only for steel, which your vintage bike probably was. Even if the frame is steel, the OP would also need a new wheel and new set of shifters. That would Penally cost more than the bike is worth.


Going to a wider cassette also means having to spread the rear triangle apart. I have done this for one additional gear. But for two gears on a 8 to 10, sounds like that is pushing it a bit.

Oh- when I did this, it was with a vintage friction shifter bike. All I had to do was adjust the derailer to expand the range. Shifters have been indexed now for awhile, so this could be a problem.

  • Sorry, that’s wrong. 8,9,10 cassettes are all same width and fit the same freehub body. Standard is 130mm OLD on road bikes, 135mm on MTB
    – Henry S
    Aug 22 at 9:48
  • Ah, I stand corrected. My conversion was different than the OP, my vintage bike used a 7 speed freewheel. Switching to 9 speed freehub+cassette, I had to adjust the rear triangle. That adjustment might simply have been from changing systems, not number of gears.
    – nogasbiker
    Oct 1 at 6:03

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