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MTBing with the need for speed

TheRicksterTheRickster Posts: 4
edited February 2019 in MTB beginners
I'm new to this, so go easy if I'm asking stupid questions...

I've been loving riding my Trek Roscoe 7 on/off roads and I'm in the market for something bigger and better.

I find that I can't get up enough speed on it though - so I'd like something with a higher gear (whilst sticking with a mountain rather than road bike).

What terminology, or attributes, should I be looking for when shopping around? Is it something to do with the 10-50 / 11-42 figures quotes on cassettes?

Rick

Posts

  • JBAJBA Posts: 2,820
    On a cassette the fewer the number of teeth the higher the gear. On the chainset it is the opposite: more teeth = higher gear.
    Most cassettes have an 11-tooth smallest sprocket and some of the SRAM ones have a 10-tooth. You can't get any less.
    Therefore your best bet for increasing the gearing is to fit a larger chain ring. How large you can go will depend on the chain stay clearance.
    You may also need to fit a longer chain if you fit a larger chain ring.
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  • What JBA said - smallest cog at the back and a bigger chain ring at the front.

    I think your bike has a 28T front ring, which is quite small and good for going up hills for you run out of gears on the flat stuff.

    I think you also have 11-42 on the back and I have the same on my bike. I run a 34T up front as I like the extra speed as well. It's a good compromise for me for climbing and decending.

    You can try a 32T or 34T and see how you get on? With 28T I'm not surprised you don't have enough gears.

    You'll just need to check how the chain ring is mounted as you sometimes need different length bolts.
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  • whyamiherewhyamihere Posts: 7,549
    JBA wrote:
    On a cassette the fewer the number of teeth the higher the gear. On the chainset it is the opposite: more teeth = higher gear.
    Most cassettes have an 11-tooth smallest sprocket and some of the SRAM ones have a 10-tooth. You can't get any less.
    Therefore your best bet for increasing the gearing is to fit a larger chain ring. How large you can go will depend on the chain stay clearance.
    You may also need to fit a longer chain if you fit a larger chain ring.
    There's quite a few cassettes available from the likes of e.13 which have a 9t cog. They're expensive though, and some people don't like the way they feel, so a bigger chainring is still a better option generally.
  • steve_sordysteve_sordy Posts: 2,376
    whyamihere wrote:
    .............There's quite a few cassettes available from the likes of e.13 which have a 9t cog. They're expensive though, and some people don't like the way they feel, so a bigger chainring is still a better option generally.

    The reason they don't feel right is because a 9T gear with a half-inch pitch is basically a nine-sided polygon, it is not a smooth circle. Because it is a polygon and not a circle, it is lumpy. The more teeth in the gear the less lumpy it feels. Many decades ago I used to work for Renolds, the largest manufacturer of chain in the UK, and maybe Europe at that time. I was told about the polygonal action and never to design anything below 10T. You can get away with it on a bike because it is slow speed, but a higher speed drive would have unpleasant vibration and noise.

    PS: A bigger chain ring is the cheaper way to go as well!
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