I'm between 5'9" and 5'10", and I'm pretty sure my mountain bike is too big for me. It's a 20 inch frame, and I have about an inch of clearance when I stand over it.

The bike shop I bought it from (years ago, at the other end of the country) said it was the right size, but I'm pretty sure it's bigger than ideal and they didn't know what they were talking about. Is it particularly dangerous to ride this bike? I mean, obviously top tube slamming into the crotch is one concern, but is that it? I rode it for years as a commuter, but I'd like to get into light trail riding this year.

I'm almost 5'9" and ride a 20 inch frame. I have fairly long legs, and with a smaller frame, I had a mile of seatpost showing, and the handlebars seemed too low.

It is a safety issue if you can't control it and you are not comfortable. I'm 5'9" and I ride a 17.5" frame and could ride a 15" but 17" is comfortable for me. Sizing is very important for control and comfort.

I'm 6'3" with 34" inseam and rode a 19" frame for years. A couple years ago I got a 21" frame on a full suspension.

An inch of standover is not ideal. Have you produced all the children you want? That is one concern. A second is the possibility of going over the handlebars. If the top tube is too long and you can't push your weight back behind the seat on a downhill, you might be prone to launching over the bars. Just a thought.

Is there a club or shop that might work out a trade on a smaller frame? Maybe buy one off ebay and then sell yours? Just me thinking out loud again.

Oh, I see. Maybe I was mistaken then, and it is alright. I still have to pull the seatpost up pretty high on my 20" frame, and the handlebars were so low that I added a riser stem to compensate...had the bars been any lower when I got my bike, I'd have had my nose below my belt...

Is 1" of clearance that bad, then? or is it alright?

The bike "feels big", but I certainly can control it. I have pretty long arms and long hands/fingers--not sure how this factors in, really.

Posted below

1" is not great but it's your junk! You said it yourself....."The bike feels big" and that is the tell tale of all but it's good you feel you can control it. You will love a bike that fits perfect and feels just right.

Standover height is highly overrated -- you're not riding the bike with your feet flat on the ground, straddling the top-tube.

Sounds like you're in between sizes. If it feels comfortable while riding, then you're good. Might want to test ride a medium sized bike from one of your local shops because no one here can tell you if your bike is too big.

Standover is one of the last things I'd look at when evaluating a frame. My FS bike has a sloping toptube which is crotch height or higher for most of its length. I've rarely canned myself on it. When I did, it was typically a crash situation.

Is your hardtail too big? Dunno. Do you feel stretched out on it? How long's the handlebar stem? Can you maneuver it well on technical bits? These are more important than standover IMO.

I'm 5'11 and in between sizes. I went with a Large. My table and chairs are pretty much resting on the top tube, but I'm comfortable on the bike. I haven't launched over the handle bars (yet) and I've hit some pretty nice obstacles. Every brand is different. I've found myself more comfortable on Mediums from some brands and more comfortable on Larges from others.

I agree. At first I was a bit concerned with standover height, and while I still prefer a bit of standover height, it's not something I normally target as a dealbreaker. I've crashed a few times and the lack of standover height hasn't caused any unpleasant occurences down below.