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I recently bought a Cannondale Trail SL 3 2021, and quickly realized that I need heavier gears for riding comfortably down hill and on flat ground.

Is it possible to add a second, larger chain ring and front derailleur to this bicycle?

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    Are you sure you are pedaling fast enough? 30t in the front and 11t in the back should give you 33km/h when pedaling at 90rpm. ritzelrechner.de/…
    – Michael
    Commented Apr 22, 2021 at 11:02
  • I would easily exceed 33km/h when just rolling down hill. I think It would be useful to have a heavier gear so that I can more comfortably cycle at for instance 33 km/h on flat ground and pedal at 40-50km/h downhill without having to pedal like crazy, which seems like a waste of energy. I am aware that the cannondale trail is not a road bike, but I find the lack of heavy gears frustrating at this point.
    – Francis Finne
    Commented Apr 22, 2021 at 12:01

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There seems to be a place to mount a front derailleur on the seat tube of the bicycle. It also seems to have unused ports in the down tube for routing of another cable.

Seat tube

Picture source: https://www.cannondale.com/en/bikes/mountain/trail-bikes/trail/29-m-trail-sl-3

It is possible that the same frame design is used in different bicycle configurations which come with 2 front chainrings.

Given that your bicycle currently has a drivetrain with quite large rear 12-speed cassette range (from 11 to 51 teeth), there is a better solution.

Replace the front chainring with one that has bigger number of teeth. Currently the bike comes with 30 teeth at the front, so you should go with 32 or 34 teeth. There seems to be enough clearance between the ring and the chainstay to fit a slightly larger chainring.

Replacing just the chainring is definitely easier and cheaper than adding a front derailleur, front shifter, routing all the cables, another chainring and possibly swapping the crankset as the current one may be single-ring-specific.

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  • Good point. Chainrings with up to 38 teeth (e.g. Wolf Tooth XTM8K9638) are available for the 96mm BCD crankset. Assuming such a "large" chainring fits. Would increase top speed at 90rpm cadence from 34km/h to 43km/h: ritzelrechner.de/…
    – Michael
    Commented Apr 22, 2021 at 12:42
  • thats an improvement! Very useful thank you!
    – Francis Finne
    Commented Apr 22, 2021 at 13:07
  • Is there an easy way to figure out what length of chain I would need if I change my 30t chainring to 38t and If it would even function correctly?
    – Francis Finne
    Commented Apr 22, 2021 at 13:45
  • or any other number of teeth for that matter
    – Francis Finne
    Commented Apr 22, 2021 at 13:46
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    @Michael the chain only wraps half of the chainring, so the move from 30T to 32T only changes the length of chain on the chainring by one link, while chain length can only be adjusted in 2 link increments (inner link + outer link). without knowing anything about the bike, in theory there’s a 50% chance that following Shimano’s procedure for sizing the chain would yield the same number of links for any given pair of chainrings two teeth apart.
    – Pisco
    Commented Apr 23, 2021 at 22:27

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