Hello, my wife just bought a 3 speed Sikk (Big Tire) beach cruiser. From the moment we put it together the gears slip in and out of gear. Does anyone have an idea on how to prevent this from happening without us having to send the bike back?

With 3 speeds most times you have to adjust the cable that operates the gears. A local bike shop could do that for you but you will pay for the work. Since I have no idea who made the drive train for your bike that is the best I can answer. Roger

Look up adjusting the specific hub on YouTube. There's most likely nothing wrong with the bike, as bikes need adjustment/a tuneup to ride properly.

Thanks for the info. I will take a look at it today and/or have her take it to a bike shop. I am a little disappointed in Sikk Bikes as this is a brand new bike. I got one of these (7 Speed) a few months ago and it is perfect. One would think when you drop 600 bucks on a bike you would not have to take it in for a "tune up" prior to using it. I would not buy another Sikk bike

FYI: you got lucky with the 7 speed. Most "good" bikes come boxed up needing a tune-up,...unless specifically mentioned by the company.

Is it a Shiumano Nexus 3 speed? If so, it is very easy to adjust. put the shifter in 2nd gear, then on the axle part of the shifter (bellcrank), turn the barrel adjuster screw until the red mark in the window lines up between the 2 lines. That's it!

If it is a (Sturmey Archer (Sun Race), place in 2nd gear, rotate the pedal to settle the gears, adjust the barrel screw until the pull rod at the end of the mini chain is flush with the axle (you will probably need to pull off a plastic protective cover to do this)

Both these adjustments are on YouTube videos.

Don't be annoyed if a barrel adjustment is out of whack. Even the most prestigious of bikes must deal with these adjustments. It is something the rider needs to know how to do. Cables stretch, and housings settle. They must also be readjusted every time the rear wheel is removed.