Starting up on a road bike

Buy a 2nd hand road bike. As long as it's in good condition you'll get more bang for your buck.

I'd avoid Gumtree but there are plenty of Facebook pages where you can search for a bike or even post an advert up saying you're looking for a road bike at £250;

https://www.facebook.com/groups/198728110180843/

Make sure you get a half decent bike for that price though. Have you got a roadie friend that could give you some advice and perhaps look at the bike?

At £250 for a 2nd hand road bike you should be looking for something with at least Shimano Tiagra gears.

As for the size 58cm is WAY too big. I'm 182cm, inside leg of 82cm and my bike is a 55cm. A 54cm would probably do you.

Aye a 58 is way too big.

I'm pretty much the same size (5'9" & 29" inside leg) as Snorrarcisco and I ride a 54 - tried a 52 recently and it was too small for me.

Obviously things vary by brand and I have no experience of Carrera. Unfortunately Halfords tend not to offer test rides and don't have geometry charts on the website

Also, if you do end up buying from Halfords it may be worth joining British Cycling as you'll get a 10% discount. This might not be worth it on a £250 bike but if you decide to get something slightly more expensive.....

Below is some text I snatched off the web, but outlines the Lemond method of frame sizing which always worked pretty well for me. At least this way you are actually basing your choice on something you can measure rather than random guess work.

DETERMINE YOUR PROPER FRAME SIZE
To determine your proper frame size, you’ll first need to get an accurate inseam measurement.
Stand with your back against a wall, your bare feet 6" apart on a hard floor, looking straight ahead. Place a book or carpenter’s square between your legs with one edge against the wall, and pull it up firmly into your crotch, simulating the pressure of your saddle while riding. Have a helper measure from the top edge of the book to the floor, in centimetres. (You can convert inches to centimetres by multiplying inches by 2.54.) Repeat two or three times, for consistency, and average the results to get your inseam length.

LeMond’s formula, from his former coach, Cyrille Guimard, establishes C-C size by the formula 0.65 x inseam length

FRAME SIZE
Frame size refers to the length of the frame’s seat tube. Pro frames are measured along the seat tube in one of two ways, centre-to-top (C-T) or centre-to-centre (C-C). C-T measures the distance from the centre of the bottom bracket to the top of the top tube or seat lug. C-C measures from the centre of the bottom bracket to the centre of the top tube. Since C-T measures to a point higher on the frame, a frame measuring 55cm C-T would also measure roughly 53.5–54cm C-C, a difference of 1–1.5cm.

I'm no expert but I would say 58 would be too big for you depending on the manufacturer.

I'm 6 feet tall & usually between a 56 & 58 so I would've thought a 54 or 56 would be about right.

Trying it out if you can is of course the best way of finding out.

I'm 177cm with 29" legs. My bikes are 54cm. The seat post is quite long and I could see a 56cm bike being ok. But 58cm would be too big I think.

check out the thread a little further down the forum with someone asking a very similar question. A few good links to other bikes on that thread.