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  • The frame and fork of this "little bear" are made from high-tensile steel that's tough enough for life around the neighborhood and in the woods
  • 7-speed Shimano drivetrain is controlled with grip shifters to charge up hills; powerful disc brakes allow controlled descents and stopping
  • 4-in.-wide tires sit atop 20 in. wheels; low tire pressure allows the bike to grab every bit of traction available, with extra float for soft surfaces and sand


All bicycles sold at REI include a free warranty tune-up. New bikes go through a normal break-in period, after which readjustment is important for longevity and performance. Bring your new bike in to your local REI for its free tune-up within 20 hours of use or 6 months from purchase, whichever comes first. Contact your nearest REI bike shop to schedule this important service.

View all Diamondback Fat Bikes

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Best Use Mountain Biking
Frame Hi-Ten steel
Fork Hi-Ten steel
Crankset Steel, 40t
Bottom Bracket Square taper
Shifters Shimano RS-35 Grip Shift
Rear Derailleur Shimano Tourney
Rear Cogs Shimano freewheel, 7-speed
Number of Gears 7 gear(s)
Brake Type Mechanical Disc Brake
Brakes Mechanical disc
Brake Levers Alloy
Rims Diamondback Jr Fat
Front Hub Steel loose ball
Rear Hub Steel loose ball
Wheel Size 20 inches
Tires Chaoyang, 20 x 4
Tire Width 4.0 inches
Handlebar Shape Riser Bar
Handlebar Alloy
Stem Ahead
Seat Post Steel
Saddle Jr Mountain
Pedals Resin platform
Headset Threadless
Chain KMC
Weight 35 lbs. 8 oz.
Bike Weight Bike weight is based on median size, as sold, or the average of two median sizes.
Gender Girls', Boys'

Size chart

Sizing notes

Bike measurements are stated in millimeters.

Rated 5 out of 5 by from Bike that goes everywhere...anywhere Living on the coast and being outdoor enthusiasts, we got El Oso Nino for our 6 year old son. We ride on the beach weekly and will take it to the mountains for snow riding in the winter. Our son is approximately 3'6" and can cruise around on this. We ended up getting a 24" Fatboy from Specialized for our 9 year old. The fat bikes make riding in any and all conditions accessible. Inflate the tires to max PSI when cruising on the beach. Let some air out when hitting the MTB trails. No matter where you go you've got the bike to go with you.
Date published: 2016-06-17
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Where do I get inner tunes for this bike? is it 20 x 4/4.9? That is all i see.

Asked by: JMAN DAD
​We recommend checking with a local bike shop. Tubes may be available directly from a supplier.
Answered by: REIservice
Date published: 2016-08-16

my name is Sarah I'm 5'8 and 31 does this fit women or just young girls ? I also want to ride off road can I do that or will my tires pop ?

Asked by: sarah68
The suggested rider height range is 47 - 56 inches. For more information on sizing a bike, please click the following link:
Answered by: REIservice
Date published: 2017-04-24

Hi! I'm a girl and I love biking!! My height is 5'2 and I'm 13 y/o. My question is..Do you ship this to Philippines? Because, I wanna buy one ;) plss reply as soon as possible!

Asked by: TheGirl'InBike
Diamondback products can only be shipped to U.S. addresses.
Answered by: REIservice
Date published: 2017-05-10

I'm looking at fat tire bikes for bikejoring. I'm 5'2" w/short legs so have trouble fitting bikes.What are the following specifications on this bike: 1) Minimum and Maximum Height at the seat? 2) Minimum and Maximum Step-over height?

Asked by: TriciaS
​The stand over height for this bike is 22.68". The maximum seat height from the top of the seat to the bottom of the pedal stroke is approximately 25.5", whereas the minimum is 18.5".
Answered by: REIservice
Date published: 2017-03-29

Does this ship with pedals?

Asked by: XPMC
​This bike does come with flat resin pedals.
Answered by: REIservice
Date published: 2017-05-10
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