I am a road bike rider and racer anybody know if there are any benefits to cycling from unicycling, I cant get my heart rate as high with unicycling as i do on my road bike it also seems because the posture is different the muscles function in a different way when peddling. Any thoughts, my longest uni ride is 15miles on a niner, I think 20 miles is within my reach soon but i wonder if my road riding will suffer… the unicycle is addictive…
It probably depends on your riding style. Before I sold my Trek to buy another unicycle, I was a very strong road rider and enjoyed dogging guys on their Lightspeeds, but I did A Lot of standup pulling high gears over spinning, and wound up going to a fixie, so it complemented muni more than if I was a spinner. Everyone is an individual, so there may not be a simple answer. If you ride hills and never leave the large chainring, then it may help you. Of course, this should lead to disagreements from bikers as well as uni riders.
Please note that bicycling and unicycling are subsets of cycling. So is motorcycling, but let’s not go there. 
You definitely work different sets of muscles, or at least different parts of those muscles, from one to the other. Also, like JohnR said, the specifics depend on what kind of bicyclist you are, vs. the type of unicycling you want to do.
Also note that your road biking may have to suffer a little for your life as a unicyclist to reach its potential.
You want to get your heart rate up on a unicycle? Pick a track with an unmade/loose surface that goes up a long fairly steep hill, then ride up without stopping.
Unicycles, having either direct drive, or a very low gear ratio, teach you to spin faster - a skill which can transfer to bicycling. On the downside, most unicyclists use cranks that are appreciably shorter than the standard 165 or 170 mm used by road bicyclists, so you may be using different muscle groups.
Taking up unicycling to improve your bicycling is like taking up violin to improve your guitar playing. Yes, there will be an effect, but that isn’t really the point.
I used to do regular 100 mile days on a bicycle. I used to ride on and off road. I was also a keen tandemist. I now feel that, given similar terrain, a unicycle ride is just more rewarding and more simple fun than a bicycle ride. That is a matter of personal taste and preference.
Thanks for the responses, all make sense, im hooked on unicycling but not ready to give up road riding yet. havent done too many hills yet will try that for HR response. Will see how keeping up with both goes.
I do triathlon (so a lot of road biking) and a lot of Muni. I think muni helps climbing on the bike, but riding a bike is the best for getting better at riding a bike. That’s sounds stupid, but is true.
for what it’s worth…
I raced distance road and criterium as well as track for years, and at first I was a little disappointed with uni because I couldn’t generate the speed and resistance necessary to get the aerobic workout I was hoping for. All that changed once I got fairly decent at riding a large wheel for long distance with a t-handle attached (helps you spin). Today’s fairly short 20-mile ride was a blast, and is a pretty typical case in point: In addition to a pretty good aerobic workout, I was of course spinning a fixed-gear wheel for 20 miles, which has benefits for anyone who rides a regular bike, because it extends your maximum sprint interval. After doing road uni for a few months, I noticed that on my regular bike, I can flat-out sprint for a much longer interval than before. This is the same sort of effect that my coach was hoping for when he forced our team to train on fixed gears for part of the time. It’s sort of counter-intuitive, I guess, because normally youd assume that your sprint interval is a function of your aerobic capacity and strength, but for some weird reason, fixed-gear training helps in this area.
Overall, I would say that doing big road miles on the unicycle while keeping your cadence high and choosing routes that offer significant hill work can only help you when you’re competing on two wheels.
I used to race mountainbikes before unicycling, and nowadays I spend most of my time on a road bike.
I think road biking is better for developing strength and fitness, unicycling tends to be high cadence/low resistance.
Except for Schlumpfs. If I were training to race unlimited unicycles, biking is great, as you have bigger gears to push.
Currently I’m mainly riding standard class, and I find this closer to running than road (bi)cycling.