What size frame?

[TechMech]

I'm looking to put together a hard tail mtb, however, i'm not sure what size frame to use.

Bear with me one this, but according to my bicycle maintenance book, you should have at least 3" clearance standing flat footed between the crossbar and your man bits, and i've got a 33" inside leg.

So as a rough calculation, half a wheel 13" + 1" for tyre + xx" for height of seat tube (i know its angled but this is roughly right). So as i've already got a 22" frame, this calculates out as 36" = comming off on the rough stuff = flattened knackers!

As i originally bought the bike (who's frame i'm using) a few years ago, for mainly road use the clearance wasn't a problem. But i've now got a Boardman hybrid for on the road, and wanted a proper mountain bike for off road stuff.

Should i forget the frame i've got and look at getting a 19" or 20" frame? As looking at the Boardman mtb's this would seem to be the size of the large frame they have.

What do other lanky folks like me ride for XC mtb'ing? Suggestions or personal experiences welcome

 

[Steve Austin]

I got a 35" inside leg and ride a 19" mtb
I have ridden 18" bikes too.

MTB's are kinda funny for sizing. Its ok to ride a bike that is a tad small off road as you tend to move about a bike a lot more than you do with a road bike. The contact points still need to be the right places imo, but the frame size isn't all that important ime.

 

[Dinger]

What Bazzer said, I am 6ft tall but have a 31 inch leg and my new FS is a medium, I just prefered that bike in that size. My HT is a large and so is my road bike so I guess the best way is to test them to see what you like

 

[spandex]

You need a MB frame some where from a 20" upto 22" if your inside leg is 33"

 

[punkypossum]

Depends tho, my inside leg is 34 and my 19.5 fits me absolutely fine - anything bigger would be too large... (and that's a 19.5 with a fairly short top tube, other frames even fit me in an 18)

 

[spence]

Same here, 33" inside leg (6'.1" tall) currently ride a 18" On-One and a large Turner. Previous HT was a 19" Coyote HT5 and that was too large with regards to stand over, FS's have all been mediums.

Personally I'd say, like me, you're on the cusp of a medium/large or 18"/19" frame.

Each manufactures seems to have different ideas on frame design and sizing. As you say angles make a big difference. Best to try a few before you buy. I know that can be difficult with frame only manufacturers but if you ask around there's usually someone willing to let you have a go.

 

[02GF74]

^^^ what they say.
rule of thumb; road bike is 1/3 of your height or 10 inches subtracted from you inside leg trouser mearument.

for mountain bike, subtract another 6 inches.

for example, I am 6 ft 1, 33/34 inside leg and ride 24 inch road frame; have 17-19 inch mountain bike frames (as specified by manufacturer).

^^^ applies to horizontal tube road bike frames.


As ^^^ say, mountain bike frames can very in design quite a lot but the constant that does not change is the virtual horizontal top tube (virtual since most are sloping) - measured from centre of head tube to centre of seat post.

This dimension is pretty consistent on all my bikes. (top tube: 580 mm to 620 mm or 1.5 inches difference, cf seat tube: 340 mm to 580 or 9.4 in difference)

 

[ChrisCrc]

I am 5'8 and have a 20" Proflex beast and a 18" Ally MTB as well and they both fit me fine

 

[TechMech]

Thanks for all your help guys

Based on what you have said, i'm looking at 19" or 20" frames on ebay atm.

I think i will start a bike build thread somewhere when i've got some more parts together.

 

[e-rider]

6'2" and ride a 20" kona.

21" frames are massive, especially off road. Anyone who is over 6 foot and rides an 18" frame is silly; I've seen them out on the trails - looks like they're on kids bikes!