Right, maybe its watching the TdF that has done it and maybe its just the fact that this crappy weather has turned my usual mountain bike trails into a quagmire but i’m considering getting a road bike so i can get out there and get some miles under my belt without coming home covered head to toe in mud….however, road bike sizing has me confused.

I’m 5′ 9″ with a 31″ inside leg, what size frame do i need?….do road bikes follow the same sizing guide as mountain bikes (smallest frame possible, plenty of seat-post showing) or is a larger frame and less seat-post desirable?

Help….totally new to that side of things.

like MTBs frame sizing isn’t standard across road bikes, so one manufacturer’s 54, for example, will be totally different to another manufacturer’s 54 in height and length

go to a proper bike shop that knows what they’re talking about and ask to sit on a few and see what fits you

I’m the same height and leg as you OP.

One company’s 52cm was too short for me, Boardman 53cm was just right. The reach was the key thing and you may have longer/shorter arms than me of course.

Might be worth trying the Boardmans though if you are near a Halfords, as they are reduced now and are great value and quality anyway.

You’ll need an EFFECTIVE TOP TUBE length of about 54cm. That’s the horizontal distance from seat tube to head tube.

Frame size will vary by manufacturer. For Boardman, that’s a Medium. Specialized, a 54cm, Giant a Medium… Look on the web for geometry, they all list ETT these days

You’ll need an EFFECTIVE TOP TUBE length of about 54cm

That ^^^
Same height and but I have a 30 inside leg and longer torso. I ride a 54cm Specialized with a 100mm. Also have a 55cm Bianchi with a shorter stem. Both fit well.

At 5`9″ I find I’m in between sizes but personally I prefer a slightly smaller bike.

To be sure, the best thing to do is get a bike fit as part of the buying of the bike.

Cheers guys, got the day off so will pop into town and sit on a few, glad i didnt hit the ‘buy’ button on a few ebay bikes i was looking at this morning….they were 56cm+ sizes!

You are probably looking in thr 53-55cm range but it varies from bike to bike as the top tube lengths are different. The ammount of top tube drop is important whih is why the effetive top tube length is the dimension needed. Also stem lengths vary on different build as does saddle to bar drop. All this determines if the bike is right or if it it needs changes.

You have to sit on a few which is why buying over the internet is difficult unless you know what frame dimensions you need. Frame sizing guides are only a starting point.

is that a trouser length or an actual inseam?
Often when we ask people they state their trouser length which is generally 1-2 inches shorter than actual inseam.

Arm length is important but torso length is too.

The critical measurements are effective (horizontal toptube length) followed by headtube length.

if you have long legs you may struggle with a short headtube unless you’re made of elastic!

56 would have been a bit too long (I ride a 56 and am 5’10.5″. You have a longer leg and shorter torso than my Son, who’s the same height. I’d therefore err on the shorter ETT; 54 max.

He rides a Medium Boardman. It’s a lovely bike. Try one for fit in Halfords (they will unlock them for you if you ask).

giggity

Listen to JoB and don’t go on a TT length recommendations too much for now.

Most bikes in your size range will be within 10-20mm in overall reach and there’s more to it than one tube’s dimension – seat angle, head tube lenght and bar type all vary the reach. Reach and stack tells you more if comparing bikes and a try-out of a few will tell you even more. You may find what feels comfortable at first feels a bit short after you get used to road bikes too.