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I've been away and just got back into bikes after 10 years and bought a used 2011 GT Zaskar 29" MTB (similar specs to this https://www.pinkbike.com/product/gt/2011-Zaskar-29er-Expert/).

I find that the highest gear (biggest chainring + smallest sprocket) is "too easy" on flat or on downslope.. in other words, i want to be able to go faster.

I think I may need to invest into new chainring / gearset. Question is whether this bike is a good quality bike (and given the age) that's worth sinking more money into (vs get another)?

Happy to hear opinions and advice. Thanks.

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  • Can you estimate your pedal RPMs while its too easy?
    – Criggie ♦
    Sep 12, 2017 at 5:19
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    Since when was 2011 old ? My best bike dates from 1998.
    – Criggie ♦
    Sep 12, 2017 at 5:23
  • Another clarification, are you riding road or off-road ? Might be that you simply have the wrong bike for the type or riding you want to do. Road riding rarely if ever needs suspension. That's not to say you can't ride the MTB on the road, but speed and MTBs are words not commonly found together :)
    – Criggie ♦
    Sep 12, 2017 at 11:03
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    @Criggie You could be right. There wasn't much science in me choosing the MTB with road tires other than: "I've never been on a road bike and it looks hard" Lol... I use this bike mainly to accompany my 6 and 8 years who would ride on pavements and I on the road next to them (in Australia, adults are discouraged to ride on walkways). We only do 6-10kms at a time.
    – Stewart
    Sep 13, 2017 at 0:14
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    Honestly, ride it as-is and work on developing your legs and core strength. . If you feel the need for speed then look for a used road bike - Mine cost $123 NZ, so not a lot different to the cost of new chainrings. And then you have two bikes.
    – Criggie ♦
    Sep 13, 2017 at 0:43

1 Answer 1

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Your specs link shows a 11-36T cassette with a double chainring with 39T and 26T. So your "fast" gear is 39:11. Assumning 29" wheels with 2.3" tyres, 1 revolution of the crank carries you

  • 8.9 metres in 39:11 (fast/hard gear)
  • 1.7 metres in 26:36 (easy/slow gear)

Basically you have a mountain bike, and its geared for off-road usage, not too fast.

11 tooth is about as small as you can go at the back reasonably, so increasing the size of your front chainring is about the only option. It may be untrendy, but a triple chainring with 50/39/26 tooth would give you 10.5 metres travelled in 50:11 which is road bike territory.

You'll need a replacement 3 position shifter and a triple crank. Your front mech may or may not have enough width to cover all three chainrings.

The other option is to replace both chainrings on your double and slide the front mech up. This will lose you the lowest hill climbing gears, but sounds like you don't need them.

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  • Thanks Criggie. I forgot to mention the tires were actually changed to a skinnier version, between a road bike and traditional MTB tires. So i guess it's a hybrid commuter bike? Appreciate your feedback very much.
    – Stewart
    Sep 12, 2017 at 7:09
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    The idea of higher gearing is quite offensive for some people, no matter how low the starting point is. I think it's just irresponsible to tell people to try to fit road cranks in a MTB. They won't fit.
    – ojs
    Sep 12, 2017 at 7:42
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    Worth noting used triples and front shifters/mechs are a dime a dozen with everyone drinking the 1x coolaid. Post on a local forum/club website and you will probably be paid to take them :)
    – mattnz
    Sep 12, 2017 at 7:46
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    @Stewart its not unusual for new users to ask off-topic and shopping questions. This one has a good underlying question of "how do I get more top-end speed out of a bike" Up and Downvotes are used to show a good or bad question or answer. The comments are ephemeral and are used to request clarification or more information, and may be deleted once no longer relevant.
    – Criggie ♦
    Sep 12, 2017 at 11:02
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    @ojs yeah it gets real messy, real fast when dealing with all the combinations. Could be this frame can't even have a FD high enough to clear a bigger chainring, plus the ground clearance decreases making it less suitable for off-road riding.
    – Criggie ♦
    Sep 12, 2017 at 11:05

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