Diamondback Boys' Cobra 20" Mountain Bike

Diamondback Boys' Cobra 20" Mountain Bike is rated 4.4 out of 5 by 36.
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NOW:$179.99(21% off!)
WAS: $229.99*


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Diamondback Boys' Cobra 20
Diamondback Boys' Cobra 20" Mountain Bike
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Product Information:

He’ll be tackling rocky hills and winding trails on the Diamondback® Boys’ Cobra 20" Mountain Bike. Made with a Hi-Ten MTB frame and trail XC travel fork, the Cobra 20 has the strength and stability needed for rugged terrain. Front and rear linear pull breaks provide stopping power. Easy twist shifters let him choose between 6 speeds.

Click here to learn more about Free In-Store Bike Assembly


  • Best for kids ages 5 to 9
  • Wheel Size: 20”
  • Frame: Steel Jr. 20" Mountain Frame
  • Fork: Zoom Suspension, 40mm Travel
  • Rear Shock: N/A
  • Headset: Threaded 1"
  • Cranks: 140mm One-piece, 40 Tooth with Double Guard
  • Bottom Bracket: Looseball BB
  • Front Derailleur: N/A
  • Rear Derailleur: Shimano TZ-20
  • Cog Set: Shimano MF-HG37 6spd Freewheel (14-28t)
  • Shifter: Shimano RS25 Revo Twist
  • Chain: KMC Z51
  • Hub (F): 36 Hole, Nutted
  • Hub (R): 36 Hole, Nutted, 6-spd Freewheel
  • Spokes: 14g
  • Rims: 36h R-1000 Alloy
  • Tires: Jr. ATB Knobby, 20x2.0 with Smooth Center Ridge
  • Brakes: Alloy Linear Pull
  • Brake Levers: Alloy Linear with reach Adjust
  • Pedals: Avenir Youth Resin1/2"
  • Handlebar: Steel Jr. Riser
  • Grips: DB Kraton
  • Stem: Alloy Quill
  • Seat: JR ATB 2-panel
  • Seat post: Steel Pillar 28.6mm

NOTICE: Used Bikes and/or bikes purchased online that have been assembled are non-returnable.

We strongly recommend that a professional bicycle mechanic properly assembles, repairs, and maintains the bicycle. DICK'S Sporting Goods will provide free in-store assembly service by a certified technician for any bicycle purchased on our website or in our stores (proof of purchase required). If you choose to assemble the bicycle yourself, DICK'S Sporting Goods is not responsible for injuries or damages resulting from improper assembly.
  • Brand: Diamondback
  • Country of Origin: Imported
  • Style: 02-14-5100


Rated 5 out of 5 by from Very Happy 7 Yr Old!!! Bought this for a 7yr old. He learned the breaks and shifting quickly. Was on the fence with the Mongoose at WM with rear suspension. Both weigh about the same. DB has a guard around the rear shifter because, even with the kickstand added, they will lay it down wrong side at some point. Hopefully this will help. MG does not have the same guard. DB was about $35 more. Either way, both are probably best for 7 - 10 yr old. MG has a cooler Black & Blue color. All said, still prefer the DB for a couple bucks more. Dicks offers a $50 3yr service plan too which we will use for the included tune ups the next two seasons.
Date published: 2017-04-09
Rated 5 out of 5 by from Great Bike My son loves his new bike. It is very well built and will be a great bike for the next few years for him! Best part was Dick's was the best price around and he was able to go to the store and walk out with it!
Date published: 2017-04-04
Rated 5 out of 5 by from Beautiful Bike! My 8 year-old loves everything about this bike. We gave it to him for Christmas and he constantly wants to be out riding it. He really likes the gear shifting!
Date published: 2017-01-13
Rated 5 out of 5 by from Great Bike Bought it for my growing eight year old son. First time with gear changing and hand brakes. We upgraded from his bike with 18" tires to this one. He loves it - which means I love it. We were in the store but they were sold out. We were lucky because one unit was in the back (sold but not yet picked up) so we could compare it to the other options. Since this model wasn't in stock the sales guy walked us over to a computer and we ordered it online, had it shipped to the store and then professionally assembled. Took one week from ordering until ready (at Christmas time). Perfect. Thanks for making this easy.
Date published: 2017-01-12
Rated 5 out of 5 by from I got one for my 7yr old son Back in my day, the Diamondback was the bike to get. His first bike was Trek and realized that it was just to much for him...had no gears and we would leave him behind ot much (it's the best bike though). So, I decided to spend a little less for a Diamondback. I live 2 hrs away from Dick's and I put it together myself. No biggie. Just make sure after a couple of days, check every nut and bolt is tight. It comes with no kick stand. Kids love to have one, get one! My son absolutely loves the bike. Changing gears is his favorite. It takes a few days for him get use to he change of pace and speed. Kids catch on fast. Highly recommend the Diamondback. We do a lot of bike trails and he has noooo problem keeping up with his older brother and myself with the gear changes. Not a trick bike! But a go fast trail blasting bike. Only one thing, tell them to slow down. Kids know no fear. lol
Date published: 2016-12-07
Rated 2 out of 5 by from Heavy and Gears Difficult Make sure you pick it up and make sure your boy can operate the gears. Our is a few years old but it weighs a TON and the gears are too hard for even an adult to turn. We ended up putting in one gear and leaving it. Before you buy, look up Diamondback Cobra online and check the weight and see whether people have reported the same issues.
Date published: 2016-11-19
Rated 5 out of 5 by from Diamondback Bike The diamondback bike was delivered as promised and in great condition. I took it to the local Dick's location and they assembled it in 20 minutes. The young man took the time to show me how to make adjustments to the brakes and the seat if needed. My 7 year old grandson will enjoy this bike for a long time to come.
Date published: 2016-11-11
Rated 5 out of 5 by from Great bike Bike is exactly what we were looking for. Customer service rep assembled the bike while we waited and fitted for my sons size.
Date published: 2016-07-20
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