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I have a Giant Reign x1 bike which has 2X factory installed 22-36t 4 bolt Sram Truvativ chainring. The question is, is it possible to find 39-53t 4 bolt chainring that can be fitted to this bike or if it's not possible what tooth ratios are possible?????

The reason I want to increase tooth ratio is my bike doesn't go fast enough on downhills no matter how fast I keep pedaling but in the same trail with my hardtail 3X chainring bike I can gain speed much better.

The highest speed record on trail, downhill, with full suspension bike: 61km/h (it's not possible to go faster unless the hill is steep slope) and with my hardtail one: 74km/h (It was possible to go faster)

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    What speed units are you using? 61-74 kmh seems pretty freaking fast. – Argenti Apparatus Aug 14 at 12:19
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    @ArgentiApparatus Pretty sure it's km/h. Miles per hour and metres per second would both be significantly faster still. – David Richerby Aug 14 at 12:26
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    @DavidRicherby I'm just amazed the OP is complaining they are 'only' going 61 kmh off road! – Argenti Apparatus Aug 14 at 12:31
  • @ArgentiApparatus Fair point. It's not exactly clear where the asker is riding: they say "The highest speed record on trail" but also "but in the same road" (my emphasis). – David Richerby Aug 14 at 12:34
  • Yeah it’s km/h and it’s recorded by Sigma Rox 7.0 gps. – Mahyar Aug 15 at 13:47
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The Giant Reign is a long travel 'enduro' bike that is designed to be ridden down steep technical trails, not pedalled down road/fire trail.

It's most likely that changing to a 39-53 will not work as the inner chainring will catch the chain stays, and even if it did work, it would compromise the bike in technical terrain, increasing the chances of 'grounding' the big ring on rocks etc. You would also probably run into problems with the front derailleur as mtb derailleurs are not designed to work with such large rings, and the frame itself may not allow the derailleur to be mounted high enough to clear the 53t ring.

In addition, it would basically turn the bike into an 'uplift' only bike, as a 39t chainring would be much too large a gear for climbing off-road terrain.

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  • Thanks Andy. But im curious if anyone has done such a thing or not. If yes im waiting for them to share their experience even if its not 39-53. – Mahyar Aug 15 at 13:52
  • @Mahyar Nobody is buying a Giant Reign with 170-180 mm suspension travel to do what you describe; in particular because it is impossible (this is what this answer is actually telling you). People wanting to break speed records tend to have custom-built bicycles/components specifically for these purposes. Consider having a custom crankset and front derailleur at least. – Grigory Rechistov Aug 16 at 7:48
  • @AndyP "it would basically turn the bike into an 'uplift' only bike" —  so true but not unheard of. I actually rode a rental Giant Reign with 36 teeth front and 11-28 teeth back in a bike park. The thing was impossible to pedal anywhere steeper than +0.01° . But nobody who had one of those was complaining about it, as the bicycle fulfilled the intended purpose: being a weight dragging myself downhill comfortably. – Grigory Rechistov Aug 16 at 7:59
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    @Grigory Rechistov I dont expect someone to buy exactly my bike to do such exact thing that’s why i said “any tooth ratios” and not 39-53 only. Thanks again for your help and replies. – Mahyar Aug 17 at 16:19

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