I’m new to the MB scene though I did spend a few years riding road bikes back in the day. In May I bought a Kona Splice 20 inch with 29 inch wheels. I’m 5 11 so it’s probably slightly too big but it was in the sale at a remarkably low price so hey ho…
I’m finding that while I’m very cycle fit, my technical abilities are poor though I’m out there trying the trails about 5 days a week. My question is: if I replace the 29 inch wheels with 26 or 27.5, will I feel more in control of the bike instead of having the feeling that I’ve got an awful lot of bike beneath me? In view of the fact that I am a newbie, new wheels would represent quite an outlay on my part so all advice gratefully received.

The wheels size is only one component of the bike. It has some characteristics but the overall package needs to be right.

Never buy a bike that isn’t the right size because it’s cheap. It will cost more in swapping stems etc before finally getting rid of it and buying a bike the right size.

Height as a measurement in modern mountain bikes is a bit misleading, reach, torso size and leg length are all important parts of the overall fit. You can devise a complex spreadsheet to work it all out with the different angles but nothing beats sitting on a bike and if your new to modern MTB’s sitting on it, riding it and having somebody who knows there too.

The best way to get technically better is to get technically better that is nothing to do with the bike. Look up some beginner skills sessions there are loads around depending on where you are, it will be a much better investment and might help kill off bad habits before you start them. If the coach is any good they will also be able to tell you a bit more about you and your bike (having seen you both) in terms of fit and feel.

You would be best to buy a bike that fits and sell the one that’s too big.

It’s a bit like wearing shoes that are the wrong size.

Hmmm.

You can’t change the wheel size on your current bike, the geometry would be all wrong. The only tweak that might help is a much shorter stem to make the bike feel less long and quicken the steering.

Thanks for the constructive advice. I’m on it.

Sounds like you have the wrong sized frame.

But there is more to frame size than the stated seat tube size (16″, 18″, 20″ etc). Not all 18″ frames are the same. Top tube length and standover are more important.

As for wheel sizes, they don’t matter either. I have a 26″ wheel bike and a 29″ wheel bike. They are for different types of ride. Both have a 16″ frame.

if you can it may be best to return it for a smaller frame. But you shouldnt worry about the wheel size. 29″ wheels IMO give more confidence as they just go over stuff.

Find a local mtb club, go on their beginner spins get some skills, your OEM tyres might be shite too.

Once you have an idea of the riding you want to do/like you can then work out if your happy with your current bike or need to swop.

It might be that you have set the bike up like a road bike and you need to adjust stem, saddle height etc etc to make it more trail friendly for your level of skill.

no biggie.