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I am having Giant Roam 2 Disc 2022 SouthEast Asia Model with the following Spec:

Stem             Giant Sport 8 Degree
Front Derailleur Shimano Acera FD-T3000 2×9
Rear Derailleur  Shimano Alivio RD-M3100
Tire             Giant Crosscut, 700x42C 60 TPI Anti-Puncture Max tyre width 53mm
Fork             SR Suntour NEX HLO 700c, 63mm
Handlebar        Giant Connect XC , 31.8
Crankset         Forged alloy, 46/30 w/chainguard
Brakes           Tektro TKD143 hydraulic disc
Seatpost         Giant D-Fuse Alloy
Cassette         Shimano HG200, 11×36
Chain            KMC X9 with Missing Link
Hubs             Alloy 28H
Spoke            Stainless, 14G
Shifters         Shimano Altus M2010 2×9
Bottom Bracket   Cartridge

I wish to upgrade my bike's crankset to get more speed. Please suggest what are the compatible options?

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    you upgrade legs to get more speed not cranksets
    – Andy P
    Jun 29 at 8:07
  • @AndyP Are those going to be left- or right-hand threaded?
    – MaplePanda
    Jun 29 at 8:30
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    @shubham What do you find is stopping you from going faster? Do you get to the 46:11 gear and find that you just want the legs to move faster ? Or do you run out of leg power first? Are you riding on the flat, uphills or downhills where you want the speed?
    – Criggie
    Jun 29 at 8:39
  • What speeds are you making now and for how long can you maintain such speeds? How much do you weigh?
    – Criggie
    Jun 29 at 8:40
  • The fastest gear you currently have should allow you to keep pedaling up to ~62km/h (requires 110rpm pedaling cadence). With a more leisurely 90rpm cadence it’s still 51km/h.
    – Michael
    Jun 29 at 10:13

2 Answers 2

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There is no possible "upgrade" currently on the market (among the big brands) for the goal you want to achieve. And if there was one, you need to make sure that the frame has enough clearance to accomodate it.

46/30 chainrings is currently the largest available size for double chainrings for MTB bottom brackets, and given the development of the market, it will probably remain so.

The alternative are not significantly larger (trekking triple chainrings).

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You're on a hard-tail mountain bike - it is never going to be "fast" but can be faster.

Easy or free changes:

  • If your suspension fork has a lockout lever, activate it when conditions don't require suspension, ie road riding. This reduces energy lost to actuating the suspension when it could be going into forward motion
  • Clean, wash, and service the bike. A dirty bike is slower than a clean bike, and a correctly lubed bike is faster again.
  • Inflate your tyres - for road riding they should be a bit harder than off-road riding. Can't say exactly, but try increasing the pressure a bit and see how it rides. Go too high and the handling will drop off and get squirrly.
  • Check the weather forecast - ride with a tail wind and you'll be faster!
  • Carry less stuff - if its not likely to rain, carrying a jacket is a extra mass. If you don't drink through a whole bottle of water, just take one.

Pay to play:

  • Upgrade the tyres to something thinner and smoother. Your current tyres are "anti puncture" and that tends to increase the rolling resistance. Downside, more punctures and you lose some of the off-road grip when in dirt and shingle.
  • Aerobars - if your average speed is up above 30 km/h then aerobars can help reduce air resistance. But they're unsafe in traffic and when manoevering a lot because the hands are so far from the brakes.

Free but hard work

  • Lose mass off the rider - this is particularly challenging, but 5 kg / 10 pounds can make a world of difference. I've added that much lately and definitely notice a drop in times.
  • Add training, practice, and experience. Regular riding will slowly improve your base performance which gives more power and therefore better speed, and more endurance at that higher speed.
    Structured training will help bring around improvements faster, at the cost of time and effort.

Expensive :

  • Replace/supplement the bike with another. It is a very nice hardtail MTB, but it will never be fast. The replacement might be a road bike, or it might be electric-assist.

Your initial request about changing gearing is not unusual, but most cyclists only have so-much power on tap, and changing gearing isn't going to do much for someone with 100 or 200 watts. The Pros can put out 400+ watts for an entire hour, so for them a chainring of 50/55 teeth and an 11 tooth rear might be ideal.

If you still want to change gearing, then try and work out what you DON'T need. For example, if you never ever use the little chainring, then why have it? You could go from the 30/46 to a 40/53 and not miss anything, if it fits on your frame.

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    In the 'free but hard work' section you can add training to get more power. Also, the roam is technically a hybrid not a MTB.
    – Andy P
    Jun 29 at 9:31
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    Please note that an ebike won't be (legally) faster that what can be achieved with this bike (except uphill or against wind). With ratios up 46/11, it's very likely that the assistance will stop long before aerodynamic drag will prevent from going faster.
    – Renaud
    Jun 29 at 10:39
  • @AndyP TBH I've never figured out what a hybrid is. We also have commuter and rigid as bike definitions, but they're all kinda similar things with fuzzy boundaries.
    – Criggie
    Jun 29 at 11:08
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    @Criggie European definitions are: basically anything with flat bars, not too wide tires and some gears is an hybrid. They are usually without fenders and racks, but if they have that, they are called commuters if they don't have front suspensions, and trekking if they have.
    – Renaud
    Jun 29 at 19:12
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    @Criggie the answer probably also depends on the region, and will probably be opinion-based (I still fail to understand why some "flat-bar gravel" are not called hybrids — except maybe that hybrids have a reputation of being shitty bikes with entry-level components, and that bikes nice bikes matching the description deserve another classification because "hybrid" doesn't sell with a high margin). Also, you know how enthusiasts can be when it comes to classification...
    – Renaud
    Jun 29 at 20:00

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