Is this too cheap to be any good?

I have no idea about that product but cheap can often mean [censored], but not always!

Don’t dismiss the phone idea. I use it from time to time and have a quad lock so it never falls off or moves. Battery packs are very cheap if power is a concern. Loads of different apps available for free or very small payments and they are all quite intuitive.

I’ve used a Garmin Edge 800 for years and it’s never been ideal. Way to much info or data for me and the menus are so confusing. I’m not sure what the newer Garmins are like though.

yes my phone falling off and smashing was my greatest concern. Never seen the Quad locks before so thank you, i think this could be a winner https://amzn.to/2VdZbs6 I would get to listen to my music at the same time will just need to look for a powerbank that i can attach to frame somewhere too.
This is why i love asking questions in forums, you get some great advice and ideas that you hadn't thought of so thank you.

I’ve used bike computers that came with a box of cereals. They didn’t last quite as long as the expensive units but did perfectly fine as long as they lasted.
I like mine to have cadence.
Wireless sensors are easier to install and look neater on the bike. Require multiple batteries and may go crazy in proximity of power lines though.
Last one I bought, a combined HRM unit, I wasn’t entirely happy with. It had too many features and couldn’t be dumbed down enough only to show what I was interested in.

Amy446446 said:

I am loking to get a little more serious with my cycling, currently just for fun and so thought i'd start with a computer to monitor my performance.
However there are so many to choose from and they vary so much in price i saw this and thought it may be a ggod start https://amzn.to/2IwNxCy
I know i could use my iphone but didn't really want to have it strapped to my handlebars just incase of accident or it falls off. I do take my phone incase i have an issue with my bike though.

You get what you pay for, and I think you'll be throwing money away. I've been using a Cateye Padrone computer, two of them, in fact, on my two bikes, and I've had no problems with them, at all. I paid around $50 (£38) for each of them. On the one bike I've ridden 6,500 miles, and 3,500 miles on the other bike. They don't have maps to follow, and they don't register calories burned, but they do register speed, mileage, average speed, maximum speed and time actually riding. They also read in meters or miles. Cateye have several models so you may find one that registers calories burned. They come in wired and wireless models. I got the wireless ones.

A few months ago a battery low signal showed me it was time to replace the batteries. However, it only flashed on for a few seconds, and the computer kept going. I don't know if that was a false signal but I changed them, anyway. The thing I didn't like about changing the batteries is that it sets everything back to zero. I like to know my total miles since I got the bikes, so I keep a file with notes, then add the new mileage to the old one. Batteries do last a long time.

Setting up a computer can be a bit of a chore. First you need to know the exact circumference of your wheel. I measured mine by laying a tape measure out on the ground. Carefully align the valve with the start of the tape measure then wheel the bike until the valve is at the bottom, again. Read the tape rule and convert the inches into centimeters. The number of centimeters is what you set in the computer. Mine came with charts for various size wheels, but I found none of the given numbers for my wheels to be accurate, particularly on my fat bike. An accurate number is essential because the computer needs to know the circumference of your wheel because it counts revolutions. Once you figure it out, it's easy.

That's generic junk, go find a lower end Sigma computer and you'll be happy. https://www.amazon.co.uk/Sigma-Bicycle-Computer-Functions-ETA-Timer/dp/B01LXDTGUK/ref=sr_1_3?keywords=sigma+bike+computer&qid=1555902263&s=sports&sr=1-3