Currently riding a large 2010 stumpy which has an effective top tube of 617mm
18" 456 effective tt is 609mm
20" 456 effective tt is 622mm
now I do feel just ever so slightly strecthed on my stumpy but i could put the seat forward slightly to counter that.
Ive rode previously the old steel 456 in both 18" and 20"
18 felt to small and gave me back ache and the 20" felt like a gate and to big for throwing around!!
current riding is commuting to work and riding around the chilterns so not to technical!
Im 182cm and inside leg of 33", slightly longer arms than average !
what would you chose !!!
cheers
steve
Given the Geo is the same on the steel/carbon 456, should really be a 20" with a nice short stem to suit the bikes character.
current set up ..........
[IMG] 
[/IMG]
previous enduro.......
[IMG] 
[/IMG]
previous inbreds .......
18"
[IMG] 
[/IMG]
20"
[IMG] 
[/IMG]
18" without question
You're only 2cm taller than me, and I'd probably buy a 16" if I was in the market for one, as they are loooooooong frames!
As im quite heavy too I found on my last to 18" inbreds i bent the seat post on both as i had to have a lot showing !!! 😆
Also I can get a 4 ride old 20" frame complete with headset for £200 which is a lot better than the £340 for a new 18"
i am the same height and inside leg as you, 82kg as well
I tried both the 18 and 20 at the on-one showroom - 18 was the choice for me
have you read the on-one sizing web page also
http://www.on-one.co.uk/help/what-size-bike
I am 2 cm shorter, with shorter inside leg and my 18" C456 fits me great. I don't have long arms though.
Morning bump for more opinions please !
I'm similar size, went from medium giant nrs to 18" On One c456. Little bit more upright, but feels better on single track, and still comfortable 4+ hrs crosscountry
I'm the same size as you, I've been riding my mates 18" 456 Ti around quite a bit
Feels like the perfect fit to me
Get the right size bike, not the cheapest.
Otherwise you'll only be back moaning about it on here again.