Tentatively in the market for a new bike. Unfortunately, the brand/model (Kona Smoke) I'm most looking at is only sold in a few less-than-accessible locations in my area, *and* I don't know what size I need. So: I'm wondering how much difference there is in the sizing of bike brands, and if it's fine to get sized on some random brand (say, a cannondale or specialized) of comprable model so I have a general idea of what size I need on the bike I actually want. (my current bike is a 15" framed specialized hardrock, and is too small for me, but I suspect I only need the next size up --on specialized that's 17", but on Kona that's 18").

Find the right size in said "random brand." Then go to the web sites of that brand and of Kona and pull up the geometry specs for each bike. Compare standover height and top tube length to match up the proper size.

If you are talking Kona- Then their 17" will not be the same as other manufacturers 17". Not only Kona but a lot of Manufacturers will measure differently. The only way to check out is to sit on and possible Test ride.

I have just bought a new bike and it was a Giant.. They seem to follow a "standard" sizing, but this was a road bike--- Ok -I have a 15" Bianchi mountain bike. Small bike and I am not that small at 5'6" but this bike suits me and my body. Had to change a few things before purchase like seat stem to accomodate me on a small frame and later had to change to riser bars. Yet I can easily ride a 17" specialised, a 17 or 18" Kona and a 19" Giant. They would not be as well set up as my Bianchi but I could ride them without any discomfort.

Back to the Giant Road bike. Started at the shop on a 44cm frame and not too bad- tried a 46 and I was stretching too far. Tried the 42 and what a difference- this one was like a glove except too low to the ground. Raised the seat post and there was sufficient length to get it perfect. Bars were just a bit low so flipped the stem to raise the bars an inch or so and I was there. I know that I will have to change afew things still on it to get it perfect- But without that going to the shop and Trying the different sizes- I could not have said I want this size with these modifications.

Remember I am not that short But I do ride bikes that apparantly are too small for me. You can always "Enlarge" a bike But trying to shrink one is Impossible.

"Not that short" haha you're my height exactly, actually . And that's been my sense -- that a 17" of five different brands will give you five different geometries, to say nothing of model. I went to my LBS and sat on a 17" Marin frame -- a little oversized for me, almost a good fit (and maybe if I'd ridden it, it would've been). But it felt gigantic compared to my 15" Specialized. The guy at the LBS thought 15" should be a perfect fit for me, but the other LBS took one look at me on it and said "no way, it's too small".

So now the major hurdle is just *getting* to one of the Kona dealers and taking a test ride. Hmm.

[QUOTE=badger_So now the major hurdle is just *getting* to one of the Kona dealers and taking a test ride. Hmm.[/QUOTE]

Take it we are talking Mountain bike. Main point is standover height and reach to the bars. Then there is height of the bars.

I like to have a small frame and standover does not really come into it- I also Ride a Tandem and this is way too tall by usual standards. The Bianchi has 3" standover height but the main thing about this bike is it's "chuckability" I can get my knees on the crossbar and manoevure around obstacles comfortably. Reach on the thing is just right for me and funnily enough my old bike, that was a 17" frame , felt exactly the same on reach. The bloke who bought it is 5'10" tall and other than saddle height he has the bike set up exactly the same as I did. In fact he has shortened the reach by putting a very short stem on from the 100mm that I used to have. When the occasion arises- he does adjust the saddle height on the Bianchi and he reckons it rides better than his bike. (Why do you think I sold It)

Then there is the height of the bars. Reach and height of the bars will adjust out but when you get a new bike- If the reach is too long or short- get the shop to change it before you buy. All I had to do with the Bianchi was a longer seat stem and FOC swop before I left the shop.

Good luck on the New purchase- But as a Kona rider occasionally- you will not be disappointed- Good bikes.

The sizes vary so wildly with different manufacturers. My 17.5" Marin is about the same size as my bf's 20" Trek. Talk about meaningless #s.