I’ve got a question for y’all… This is my second season of tris, and I’m so far doing them on my mountain bike (only bike I own!) I have road-friendly tires on it (no knobby tread), and it has front suspension only. I was able to do just over 20 mph for an oly-distance. How much faster do you figure a decent road bike might be? What are the biggest sources of the speed difference? How ridiculous would it be for me to slap some aerobars on this rig (assuming I could make the position work) until I can save up for a road/tri bike? Nate
My biggest embarrassment at my first ever tri wasn’t showing up with a 7mm scuba suit, forgetting to fill my water bottle or having to take a dump at T2, but was when a woman on a mountain bike passed me. I was riding my old down tube 12 sp at the time. She was down on aero bars but I had none so that and her better engine made the difference.
A road bike will be faster for sure but get out and enjoy the participation on the mountain bike. Don’t over look the second hand market for a decent road bike.
Well, at least now I now know there’s a precedent for putting aerobars on a mountain bike! I am just wondering if there’s likely to be a big (i.e. 5 mph) or little (i.e. 1 mph) difference between a decent road bike and a decent mountain bike set up like mine. I know, it’s a vague question…
Can’t really answer that but I do know that I pick up about 1 mph the second I drop onto the aero bars on my road bike. I also remember that the gal that passed me had road wheels/tires swapped onto the bike instead of knobbies.
Not sure I can help, but I’m also interested in the answer. Have yet to do a tri, but can average 19mph for a 35km ride, again with front susp. & road tyres. Won’t allow myself to buy a road bike until I’ve paid off all my credit cards (which will take a while).
I read somewhere that there was a 15% increase in speed between MTB & road bike for the same power output, but can’t remember where I read that, or the specifics. I’d imagine that would be an MTB with full knobblies rather than road tyres. Will try and find the page.
I recall gaining about 15 minutes over 40k going from a MTB to a road bike. But that was with all the handicaps: MTB had knobbies, no aerobars, and no clipless pedals/cycling shoes. Offhand I’d say about 5 minutes were due to the pedals/shoes, another five to the wind resistance, a few to the tires, and a few to the weight of the bike.
How wide are the tires on your mtb? Rolling resistance on fairly narrow mtb tires filled to pressures about 80+ psi shouldn’t slow you down too much. If you are not trying to win, that should get you some pretty respectable speed. The mtb’s main issue (the way you have it set up) would likely be aerodynamic–your arm and body position, the wide bars, fatter wheels, bigger frame, more so than tire friction.
I know in good tests conducted years ago, it was calculated (using power meters and a velodrome) that a rider positioned on a road bike with decent aerobars could save approx. 3 1/2 min. on a 25 mile / 40 km course at a speed of about 25 mph. Riding slower means less aerodynamic advantage, but it also means more time out on the course, so in minutes you could save just a bit more time than that.
I think 20 mph for a 40 km race for a newer triathlete on an mtb is very respectable. You would get a decent push from aerobars. But be careful: most aero clip-ons are made to clamp on road bars, not straight mtb bars. The bar diameters are different and the set-up would likely have to be jury-rigged to work and not secure. Also, the geometry of an mtb frame and stem will likely not respond well to you being far forward on the aerobars–another source of instability. Finally, as you ride on the aerobars, the distance from your hand positions to the mtb brake levers is quite a bit farther than a comparable reach on a road bike, so you would not be able to stop or slow nearly as fast.
If I was in your shoes, I might stick it out on the mtb without aerobars for a while and then move up to a road bike with aerobars when I (or my wallet) was ready. Hope that helps.
I did an entire season (my first) of triathlons on a Trek Mountain bike. For my 2nd season, I purchased a Quintan Roo Kilo (nothing extremely fancy) and found that I knocked 3 minutes per 4 miles (i.e. I trained around a golf course trail that was close to 4 miles). Hope this helps.
I would say 10-15% faster on a road bike without aero bars versus mtb with slicks from my cruising speed on both bikes. Use ritchey slicks at 100psi on your mtb if your not already. I don’t think you would gain much except somewhere else to put your hands with the aero bars. I don’t think the position would work but you never know.
I took 10 minutes off a 16 mile flat loop going from my MTB w/ road tires to my tri bike (with less effort). I average 1-2 mph faster on my tri bike compared to the road bike over the same course and roughly same HR (1-5 beats). I imagine a road bike from a MTB is worth 1 mph ish. But if your doin 20 mph avg on an MTB over on an Oly your doin pretty good.
I’ve saw a few ppl w/ aero bars on MTBs last weekend at Lake San Antonio (TNT was there), some of them were moving along pretty good. So you wouldn’t be the only one.
I did a 1:03 40k tt on a one speed mtb. It did have a 650 disc wheel aerobars and a HED deep dish front wheel and around a 100 inch gear. That is a pretty good time for me as I usually fail to break an hour by seconds to a couple min at states on any thing from the mtb to track to full aero bike.
In your case on a mtb with front suspension any where from 2 min to 4 min depending on your ability to hold an aero tuck, best guess. G
For me there is a 5mph+ difference between my mountain bike and tri bike on the road. My MTB bike though does not have aero bars and I leave the knobby tires on it.
1 factor is my tri bike has more gears for going fast than the MTB bike.
My daughter would tell you there is a hell of a big difference. We entered a local sprint tri a few years ago. My daughter, the fish, was one of the first out of th ewater. She hopped on her mt bike and proceeded to count 75 people pass her - including her non fish dad on his road bike. (of course her cross country background payed off and she proceded to trash me on the run)
How ridiculous would it be for me to slap some aerobars on this rig (assuming I could make the position work) until I can save up for a road/tri bike? Nate
People might make fun of your bike sitting in the transition and proclaim how ridiculous it is to put aerobars on your bike, however, they may quickly change their minds as you pass them on the course. Do want you want, you obviously have some talent so do whatever it takes to keep your interest in the sport.
natrin,
I met a nice girl on a century ride who was riding a mountain bike and keeping a pretty good pace, 19-20 mph, and she had knobby tires on the bike! Her cadence was at least 110 if not 115. I just marvelled at her engine! She was awesome, IMO, on that mountain bike.
At the next rest stop I met her again and talked with her complimenting her performance. She confided that her rear end was complaining as this was her first century. We were at the 50 mile rest stop at the time. She asked me if there was anything she could do to her seat to make the last 50 miles more bearable. When I saw her seat I immediately understood her problem. The nose of her seat was tilted up about 15-20 degrees. Ouch! I leveled her seat for her and suggested she try that to determine if that was an improvement. She was ecstatic about the immediate relief she felt.
She pulled into the 75 mile rest stop as I was leaving and said she felt much better and was still enjoying her first century and thanked me again for making the seat adjustment for her. She was still cranking away at that unbelievable cadence.
Yes there is precedent for riding mountain bikes in endurance cycling events. Most experienced road cyclists will recognize your effort and capability. You can figure about 10-15% improvement in speed changing from a mountain bike to a road bike as WebSwim suggested. Figure another 1 to 1+ mph by adding an aerobar as cerveloguy indicated.
You could be smoking on a road bike! But bear in mind what Greg/ORD had to say about modifying a mountain bike with aerobars. The geometry was not intended for aero position riding. Your bike will probably be a little more difficult to control. Not so much that you can’t manage it, but that over many miles your shoulders, neck and back will begin to feel the strain. Another possible consequence may be that you find it more difficult to breath in this aero position because your torso is collapsed into your thighs to a degree. Lastly, the position probably won’t be comfortable enough to maintain for any great length of time, but you will get a feel for what getting down in a more aero position can do for your speed and effort and it will give you another riding position. To a degree, road bike geometry will help address these issues indirectly. Tri bike geometry will address these issues directly and specifically.
Adding aerobars is a very modest investment and not without precedent on a mountain bike either. My recommendation would be to talk to your LBS and have them recommend bars that should work. Many touring cyclists (ala Adventure Cycling Association) put clip-on aero bars on their mountain bikes to ride with front and rear pannniers. This isn’t so much to get aero as it is to get another position to ride in.
Good luck. Sounds like you will be serious competition for cyclists in the events you enter.