I'm coming up on my first tri this Sunday (Kinetic Sprint in Virginia) as well...but everything I've read is that it isn't all that uncommon to see a mountain bike at a triathlon... I've also seen suggestions about swapping out your mountain bike wheels/tires for road wheels/tires, but you should probably talk to someone at your bike shop to get more details on that - I'm not too familiar with what would be needed for that. In the end - at least for your first one... I don't really think it matters what type of bike you ride as long as you're comfortable. I'm not aware of any rules against it either... nothing specific on the USA Triathlon website. More experienced racers might want to chime in on this one...

Additional thought: If your goal is just to finish - then your mtb is fine (I think)...

I did a local duathlon back in october and I saw a range of bikes - mountain bikes, recumbent bikes, road bikes - so drive on!

Good luck... what is your first race?

No shame in using MTN bikes, you can only do what your pocket book will let you in terms of high tech gear. In my first race I had a decent road bike and got passed by quit a few MTN bikes.

Im competing in my first tri in about two months and my mtn bike feels better for me than getting a street bike. I look into what they accept first before signin up for a tri. One im doing says you can use any type bike you want. Im mostly doing this race to see if i can do it..and finish. Not looking to get a time record set.

Congrats on the sprint! I had a blast at mine too... good luck training!\

Ross