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I just want my bike to go as fast on a road and can go trails as well.

(https://i.sstatic.net/Dkbzv.png)

Update:

I got a gear calculator app and this is what I would get if I upgrade my cassette and chainrings. A more than 10kph difference based on my normal cadence of 70. I hope this app is accurate. Kinda stick to all MTB parts and will not mixed with roadbike crank since its not workable. I think I may be pedaling slower for this upgrade but pretty sure will get used to it and improve my pedaling power in the long run.

enter image description here

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So your goal is to increase the gear ratio range of the bike for better performance on paved surfaces.

Know this: unless you are running a too-high cadence in your highest gear or completely spinning out on the road i.e., you cannot pedal any faster, there is absolutely no point in changing gear ratios. Speed is determined by the rider's power, not gear ratios.

That said...

If the picture is your bike it seems to have a square taper or Octalink bottom bracket. You can fit any compatible triple crank you want. Depending on the BCD of your spider you may be able to simply fit a set of larger chainrings.

You may be tempted to just increase the size of the big ring, but that has negative consequences:

  • Front derailleurs have a max big-small ring tooth count difference that you might exceed.

  • You may exceed the total capacity of the rear derailleur (difference in teeth big-small front + difference in teeth big-small in the cassette)

  • Shifting between rings with a too large difference in size may be poor or impossible.

Update:

Also check the above if changing set of rings or whole crank.

You also need to check that you have enough chainstay clearance for larger rings.

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  • Wow that's very scientific. I spoke to a mechanic on shops near us that its impossible to fit a 53t rings or roadbike chainrings on my mtb, however I found a MTB crankset a non series shimano that has 48t/38t/28t which is a good thing to replace my old 42/34/24 chainrings.
    – Gerard Rocky Getz
    Commented May 12, 2018 at 15:50
  • @GerardRockyGetz Check you have enough chainstay clearance, and note that the difference between 42/34/24 is 18 teeth but 42/34/24 is 20 teeth. Check your front and rear derailleur capacity specs.
    – Argenti Apparatus
    Commented May 12, 2018 at 16:02
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Sure you can, but its not going to do a lot for your overall speed.

As long as the BB to crank interface is the same, you can put whatever crank on you like.

Any older bike will have a square taper interface. Newer bikes can have Octalink or something newer again. You will require the same interface, and a crank puller to suit.

Another option is to change the chainrings for larger ones, but that can have issues with too-large a jump between chainrings.

You can also change the rear cassette for one with a smaller-small cog. 11 tooth is the common minimum size.

Downside of all this is that the bike is still about the same weight, and you're not putting in any more power. So the bike's going to go about the same speed but you'll be pedaling fractionally slower.

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  • Make sense I guess I should buy a roadbike to suit my speed preferences and upgrade this MTB to a 11tooth cassette since this is just on a threaded type hub with a 14t to 28t. I get a speed of 35kph on an average and 51kph on descends. Kinda not contented with the speed but not a bad thing for a newbie like me. This built bike happens to be cheap with low end parts. Little did I know that most parts arent shimano so yeah its time to upgrade and save for a new bike.
    – Gerard Rocky Getz
    Commented May 12, 2018 at 15:34
  • @GerardRockyGetz A threadded type is a freewheel, and they are limited to 14 tooth at the smallest size. Occasionally a 13 tooth might be found but that would be your smallest. Your best option is to replace the rear wheel, with a freehub and cassette, keeping the number of gears the same so you keep the same shifter. Or just ride it as it is and buy a more-road bike for the faster road rides.
    – Criggie ♦
    Commented May 12, 2018 at 23:02
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enter image description here I got a gear calculator app and this would I get If I upgrade my cassette and chainrings. A more than 10kph difference based on my normal cadence of 70. I hope this app is accurate. Kinda stick to all mtb parts and will not mixed with roadbike crank since its not workable. I think I may be pedalling slower for this upgrade but pretty sure will get used to it and improve my pedalling power in the long run.

Improve this answer

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