Understanding MTB Sizing

[Jezston]

I'm looking for a half decent mountain bike frame for a far too long ongoing project - currently have an old Raleigh Alaska which is made from galvanised iron and is far too heavy - however I'm a bit confused by mountain bike sizing so want to make sure I'm looking for the right thing.

For an older style, non-compact, flat top-tubed, horizontal dropout style mountain bike frame, what would be the equivalent of a 56cm road frame?

Thanks!

 

[Crackle]

17.5" or thereabouts, I reckon.

 

[SatNavSaysStraightOn]

my OH is meant to fit a 17-18" frame he is around 6'0". apparently I am better suited to a 15" frame at 5ft 6inc, but I have a 17" frame which I prefer and my OH uses a 19" frame which he prefers - doubt that clarifies anything but may give you a clue. If it is slightly too big you can shorten the stem a touch, better than than too small IME... (my road bike is a 54cm frame btw).

 

[festival]

For the kind of frame you have described, up to 19" would be ok if it was "old style and the top tube was not too long, otherwise 17"/18".
Its generally better to go slightly smaller than larger, depending on were you are riding.

 

[Peteaud]

I am 6' and ride a 19" Hardtail.

Road bike is a M/L (Giant)

 

[Jezston]

Sorry for the lack of reply - thanks for the info.

 

[lulubel]

[quote="SatNavSaysStraightOn, post: 2215128, member: 10876"If it is slightly too big you can shorten the stem a touch, better than than too small IME...[/quote]

It's the other way for me. I prefer small (5'2" and ride a 13" frame). There's nothing quite as scary as feeling "over-biked" on a sketchy descent.