I'm just over 6ft tall with long legs (92 cm inseam), and can't decide between 18" and 20" Orange ST4.

I'm currently riding a 19" Orange P7 with a 90mm stem, and like that very much. In the P7, the top tube is 600mm just like in the 18" St4 frame, but the 18" would show a ridiculous amount of seatpost with my 78 cm saddle height.

On the 20" ST4 frame the top tube length is 2 cm longer, but I could have the same cockpit length with a 70mm stem. Do you think the 20" frame would be too big?

I think the ideal frame for me would be 20" with 600mm top tube but Orange doesn't make it, and I'm torn between 18" and 20".

If anybody has pics of a 20" ST4, It would be nice to see them…

6' bang on here, 33" inseamish and on an 18". I had the same dilemma – go small n nippy, or longer and nicely 'strecthed'. Glad I went small n nippy…

I ride a Five but have ridden an ST4 quite a lot, they feel the same in terms of fit.

At 5'10" an 18" is what I'd call comfortably "roomy" so for a six footer an 18" would be on the nippy/flickable side. If you're looking for a more all day kind of bike, consider a 20"

I personally think Orange's are better on the slightly larger side as they're strength is in their sledgehammer like ability to roll through and down anything at speed and I think the longer wheelbase of a larger frame amplifies this…

All IMO of course…

Thanks for the replys… Matt_outandabout: What's your saddle height in the pic?

What I normally ride – never measured, but I have 15-20mm before the minimum insertion mark. Standard Orange Stick-Up post.

Competitive Cyclist Fit Calculator

I set up my hardtail and my roadbike according to these guys. It gives you figures for BB-saddle, ETT, stem length, and saddle-bars. Once you have these you can compare them to how you run your current set-up and use it to judge changes in top-tube vs stem etc.

If you are wanting something thats good craic stood-up, down hill, I think you are on the right track with a 20" and a 70mm stem.

Cool toy Shandy on Competative cyclist – I am bang on the All Mountain sizing for an 18", and bang on for the XC on a 20"

Measured up me and my bike, pretty accurate and comparable with its dimensions – good site.

Its pretty clever. I am a strange shape, tall with long arms and legs but a short trunk. It balanced everything out very nicely on both bikes and gave me a starting point to fine tune things from. I'll be much more confident picking a frame size now.

I've got that Sitting Pretty DVD which is also helping – pricey though.

Found a photo from flickr, and after some measuring in Adobe Illustrator, i came up with this image: 🙂

(Couldn't find a pic of a 20" frame anywhere)

Above is a mock-up 20" frame with 70mm stem, below a 18" with 90mm stem. Saddle height is 78 cm in both bikes.

I think the 20" looks like a more balanced setup. Only the longer wheelbase makes me wonder if it's too clumsy when riding twisty singletrack…