2014 Diamondback Jr. Viper

2014 Diamondback Jr. Viper


Specification            Description
Best use                 Cycling 
Bike style               BMX bike
Bike frame material      Steel 
Frame                    DB high-tensile steel 
Bike suspension          No suspension 
Fork                     BMX high-tensile steel    
Crankset                 1-piece steel, 36t
Bottom bracket           Loose ball 
Rear cogs                18t freewheel 
Brake type               Coaster brake
Brakes                   Rush V-brake
Brake levers             Rush RX2.1
Rims                     Alloy
Front hub                Steel, 36h
Rear hub                 Steel, 36h
Wheel size               20 inches
Tires                    Comp III Style, 20x1.75
Handlebar shape          BMX bar
Handlebar                Steel BMX
Stem                     Alloy quill
Seat post                Steel pillar
Saddle                   DB BMX Padded
Pedals                   Resin platform
Headset                  Threaded steel
Chain                    KMC Z410


The brakes on the handlebar are really hard to pull and make a popping noise when you pull all the way in. Also, when you just roll the bike, it feels like as it rolls, the brakes are being applied. We've already taken the bike back to REI to have them adjust the brakes and/or spokes on a truing stand. I don't know what else to do or how to correct the situation. We simply want the bike to be able to roll freely and have the brakes apply only when depressing the pedal or the handlebar brake.

  • You say you've taken it back to REI for adjustment. Does that mean this is a new bike you bought from them? If so, take it back again and make it clear you'll keep being back until they get it right, or you'll start making noises about wanting your money back if they can't. Dec 6 '13 at 2:29
  • Pick up the bike and spin each wheel by hand. Both should spin freely and the front a hair longer than the back. If the back wheel is dragging, slip the "noodle" loose from the brake (easy to do by hand) so the brake arms are well away from the tire and try again. If it still drags it's a bad bearing, otherwise the brakes need proper adjustment. Dec 6 '13 at 3:22
  • For some reason, I've found a lot of people have bikes set up in a way such that you can't use the quick release on the V-brake. If you can't push together the arms and pull the cable away from one of the arms, you'll need to loosen the cable with a hex key or bolt on the arm its clipped to. If they do spin freely, the answer below has a comment which gives links to adjusting V brakes.
    – Batman
    Dec 6 '13 at 16:45
  • Thanks guys. Yes, we bought it online and had it assembled at REI. The guy there seemed to be very capable of fixing such a supposedly simple thing. I'll just take it back again I guess. I thought I could easily adjust it myself. I don't like relying on other people, especially when that store is almost an hour away from our house. Dec 7 '13 at 0:03

This bike looks to have a vee brake seen on (now old school) mountain bikes.

The popping noise you notice could be the cable housing not sitting in one of its barrels. And, pulling the lever that could cause it to move suddenly in/out of place. It could also explain why the wheel isn't turning well: the housing could pull on the cable, and hence the brake. Check the housing, if it keeps falling out of the those little barrels, it may be because the housing is excessively long. Have REI shorten it for you -- you can do it yourself, but you'll need something more than those needle noise pliers. ;)

If that's not it, check the wheel. Ensure it's sitting center in the frame. Lift the bike and turn the rear wheel, if the brake pads are really close to the rim, then you will want to give out a little slack to brake cable. If one pad rubs, adjust the amount each brake arm's spring pulls outward. (There should be a small screw on the side of each brake arm.) I like to balance the spring tension, so if you tighten one arm, loosen the opposing arm.

Hope that helps.

  • The barrels seems plausible. To shorten it, I think the best way is probably a dremel unless you have the right cutters. See sheldonbrown.com/rim-brakes.html and sheldonbrown.com/canti-direct.html and make sure the cables are installed properly. At most REI's, the people aren't really much more trained than the guys over at walmart (though they have better bikes), so you may need to go to your local bike shop for a fix if you can't figure it yourself.
    – Batman
    Dec 6 '13 at 0:32

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