it's not much of a loss. I can verify that with powertaps and SRM.

I bought a Costco Schwinn before that Iron Horse... I can't even consider those stats to have merit as the bike only lasted me 2 weeks before the wheels flexed from my weight and paltry torque to the point of rubbing the inner chain-stay every time I utilized the right crank arm.

..speaking of which... does that Walmart bike have a suspension system? That would suck ass too.

You were saying that it's still pretty significant even on $5k bikes and I'm saying it's not.

Yes. And yes it is annoying, especially going up a hill.

Adjusted the brakes. Adjusted the seat. Pedaled harder.

8 miles in 48 minutes. Still in last place, but maybe a few people stuck around to watch me finish.

It is foolish to assume things. I recall one female who I saw climbing who was in way to high a gear and was going up and dwon like somethign on a merry-go-round.

When I first started riding my first bike was a mountian bike, fixed frame and pretty decent bike. There was more than the 3 mph difference other mention comparing that with slicks to my road bike. BUT I was a bit of a grinder and I easily was topped out on gearing once the slicks were on it.

If the OPs bike is a cheap suspended mountian bike with knobbies at mountian preasure and resonably poor drivetrain lubrication 5 or MPH difference could be reasonable, especially if he is going at low RPMs and betting the suspension going.

Are you saying I am being foolish or are you in agreement with me?

My thought too. FWIW, I think 9 mph on a cheap 35 lb MTB should translate to 11-12 mph on a good-quality used 24 lb steel/alu roadbike. Maybe more in a race, your adrenaline gets pumping, your putting out more watts than just riding by yourself, tooling around. That's what being in a race does to your brain and bod.

This being said, OP needs to get into better shape, and if he can do 20 mi/day 5-6 days a week for 6 weeks, and push himself, not to puke levels, but to "I am really bushed," the speed is going to increase.

Bottom-tier bikes suck. They are made for 9 mph, "I'm riding the MUP, if the weather is 75 degrees; I'm not really interested in committing myself to this cycling thing," easy-pace weekend riders. OP's WM bike is not made for any kind of race, XC trail or road. A good raceable mid-range MTB is 24-26 pounds, not 35.

Any roadbike will just feel more responsive when you crank it, and make you want to crank harder and faster. I could see OP doing 15 mph , with 6 weeks getting into better shape from consistent diligent daily riding, and with the adrenaline flowing on race day.

OP, i think the biggest thing you would notice if you switch to another bike is the lack of suspension. Even if you drop $300+ for a brand new entry-level, but name brand mountain bike (not particularly recommending it, just an example) you'll notice a big improvement from lack of squishiness. That's what I used to hate about my walmart beater growing up. I couldn't spin up to any real speed without bouncing up and down like a jack-in-the-box. Like I said, they make the shocks way too loose, probably so people will notice it over little bumps on the sidewalk.

6 weeks is a little bit too short a time to reliably hunt down a good deal on craigslist or ebay, but I would recommend that route. You might be able to find a good deal on an older steel road bike for ~$100. Make sure it fits, and it might be a good idea to get to know your local bike shop. Their advice will be helpful, and you might like for them to do some work you are not comfortable doing. Mine at least does tune-ups for pretty cheap.

If all else fails, switch over to slick tires. Sure it won't make the biggest of changes, but you can usually get some decent slicks from performancebike.com or nashbar.com for $30 for a pair ($14.99 or something each) on sale. Now my level of decent is different than most people on here's, but it's probably the cheapest change you can make if you can't find a yard sale bike that fits.

It's really starting to get off topic now, so this is the last time I'll post on this, but even 1-2% is significant. 1% loss is the difference between 25 mph and 24.75 mph. Lots of pro's spend time in a wind tunnel trying to gain a lot less than that in aerodynamic advantage.

Yes I agree that when racing 1% can be significant, but it was really in the context of the comparison to fixed gear bikes and low end bikes with "shoddy components".

thats also 16mph vs. 15.68mph. I guess I'm slow and inconsistent. I'd call that a normal variance, depending on how hydrated he is and what he had for dinner the night before, whether the tire pressures were off by a little bit?

Sorry, didn't mean to sound like a dick. Wasn't my intention.

I just meant that you're doing something wrong. Your time should be so much faster that that. If you can run 5 miles in 50 minutes, you're pretty healthy.

Forget the bike for now - just ride it for as many hours per week as you can - and focus on the run leg.

Honestly - I still think you are calculating something very wrong here unless your entire route is uphill? I swear I am not trying to sound like a dink - I took my 6 year old on a bike ride that was about that far the other day and she averaged almost 9 mph vs. your 10 mph and she is riding a 20" wheeled, single speed Trek Mystic girls bike. There has to be another explaination here because something just isn't adding up?

Are you counting time spent stopped to wait for traffic signals, etc in the total time?

Try using www.mapmyrun.com and enter your route - this site is awesome.

Wow. That site is awesome. Thanks.

I'm bascially riding a 2.3 mile loop. The elevation difference is 242ft. The low point is at the beginning and the high point is around the middle. Is that bad as far as hills go?

I don't spend more than a few seconds stopped during the ride.

That'd be ~968 feet of elevation for four laps, which is more than I see in a 60 mile ride. Might be easier to judge if you could link the course map+profile

100 ft/mile is often considered pretty hilly. That would certainly slow you down, especially if you are heavy (I don't remember if you said and I don't care to go back and look through all the posts). It also would make the extra weight of the mountain bike have more affect, and the suspension

Too vague.

Here are some numbers.

http://74.125.93.132/search?q=cache:...&ct=clnk&gl=us

Power 1-sp 3sp-L 3sp-1:1 3sp-H 6sp-24 6sp-19 6sp-13

50W 96 90.6 93.4 87.3 94.2 94.1 92.1
100W 97.3 92.8 95.7 90.9 96.2 96.4 94.9
200W 98.1 94 96.9 92.9 97.4 97.6 96.9
400W 99 95 97.9 93.9 98.1 98.4 97.8

I doubt you'd feel the difference between a "$5k bike" and a "decent" fixed-gear.

Here's a link to the loop I'm riding: http://www.mapmyrun.com/route/us/va/...27170038680981

I got my time down to 45:30 for 8 miles today (I do the loop 3 times and ride 1/2 mile to/from the loop)

I'm 5' 11" and 185 lbs.

10.6 mph.

Help us out and provide the average MPH too.

If you want to do more road riding (outside of this one event), then get a road bike. But don't expect magic.

I'd guess that you would have maybe done 12mph on a road bike with the reduction in resistance (thinner high-pressure tires, no cheap-assed suspension) and a better aerodynamic position (if you use the drops).

I alternated between a mountain bike with slicks and a road bike for commuting over a period of several years. The difference was 4 mph - about 20 mph on the road versus 16 mph for the mountain over a 22 mile one way distance and included time at traffic lights and intersections where cars caused me to stop

Stupid but honest question - he's doing loops and ending at the same elevation that he started out at... shouldn't he be making up a little time on the down side, anyway?

I'll take a stab at this and say "a little." The potential energy you gain from climbing the hill = mass * gravity * change in height. Going down the hill converts that potential energy to kinetic energy (0.5 * mass * speed^2) but the faster you use it up (i.e. higher speed) the more is lost to wind resistance (doubling your speed = 4 times as much wind resistance). Basically, going down the hill faster will be a less efficient use of the energy you stored when you pedaled up the hill.

A little but you never get back as much time as you lose going uphill. It's the same as in a headwind/tailwind situation. You spend far more time going slower than you spend going faster, so you don't have enough time to make it up.

To illustrate an example, if you climb up an 8% grade at 4mph for an hour you would go 4 miles. Using the calculator here, if you turned around and went back down that 8% grade and put out the same power you would go 37.2 mph, or 45mph in the drops. At 45mph, that 4 miles would take 5 minutes and 20 seconds. So the 8 miles total would take 1 hour, 5 minutes, and 20 seconds, at an average speed of 7.35mph. If you use the calculator and remove the grade, the same rider could have done the 8 miles in 29 minutes and 49 seconds, or 26 minutes and 31 seconds in the drops.

Good explanation of the energy equation!

The simpler explanation is that you can't really go fast enough to make up for the loss of time that going slowly uphill costs.

Let's say there's a 10 mile run up a mountain. Let's say one travels up at 5 mph for 10 miles (2 hours) and coasts down at 40 mph (0.25 hours) (reasonable numbers for "normal" people on a "good" grade).

That ends up being 20 miles over 2.25 hours. The average speed would be 8.9 mph. If this course was flat, 15mph (in an aerodynamic position) would be fairly easy to do.

If you could increase your downhill speed to 80mph (just like umd), your average speed would be still low: 9.4 mph.

It's very hard to go fast enough (due to aerodynamics and the simple reluctance to go very fast on a bike) to make up the loss of speed going up hill for such a long time. (In my example, it took 8 times as long going up as going down.)

Hills do horrible things to your average speed!

I don't know if it was due to bike weight, components, wheels, gears, etc., but when my wife and I went from hybrids (I would say lighter and less tire than mountain bikes), our speeds were better. So, yes, I think it will make a difference. I like the suggestions you've received to borrow a bike. My wife did that for her first tri and then bought the same bike later.

If you're not strong up (short) hills, bike weight is not going to make a huge difference. I suck just as much on rollers on my mountain bike as I do on my road bike,

Don't worry about it. If you call me a weenie it should make me work harder and that's what I need anyway :-)