Road Cycling - does the bike matter?

I just completed my first sprint triathlon using a $100 mountain bike and I'm wondering how much faster I might have been on a decent (below $1000) road bike. My swim and run times were solidly in the middle of the novice group while the bike was near the bottom.

You would have been A LOT faster on a descent Road bike below $1000, instead of using your Wal-Mart brand mountain bike! Road bikes are built for one thing. To be fast on a paved surface. You should check out some of the sub-$1000 road bike models from Felt, Specialized, Cannondale, Motobecane, and Giant.

Aside from other factors like narrow tires, aero positioning and so forth, one simple factor is weight. Since it is indirectly proportional to weight, you can simply calculate the difference in weight.

Let's say you weigh 150 lbs. and the mountain bike weighs 25 lbs. That makes 175 lbs. If a good road bike comes in around 20 lbs (for easy calculation's sake), that would make your total weight 170, which is about 3% lighter. All this means that with the same power output you would have improved your time by 3%. That's no small potatoes in a race.

Cheers.

Originally posted by jmlee

Let's say you weigh 150 lbs. and the mountain bike weighs 25 lbs. That makes 175 lbs. If a good road bike comes in around 20 lbs (for easy calculation's sake), that would make your total weight 170, which is about 3% lighter. All this means that with the same power output you would have improved your time by 3%. That's no small potatoes in a race.


That's BS. There's no way you can say "3% weight off and your time will brop by 3%". Sure, lighter is better on accelerations and uphills, but anywhere else, it doesn't matter.

Originally posted by Ovara


That's BS. There's no way you can say "3% weight off and your time will brop by 3%". Sure, lighter is better on accelerations and uphills, but anywhere else, it doesn't matter.

Ovara is correct. Objects in motion tend to stay in motion.

Bike weight only effects accel and climbing.

Originally posted by mike


Ovara is correct. Objects in motion tend to stay in motion.

Bike weight only effects accel and climbing.

To make it even more confusing, the heavier person/bike will go FASTER on downhills.

okay...so aside from weight, what about the skinny tires and aero design...?

I find that I typically ride about 2-3mph faster on my road bike versus my mountain bike (with slicks). However, I don't ride either of them at racing speeds.

Timerigger, ask yourself this question: If the weight of the bike didn't matter, would the top athletes demand lighter and lighter equipment; even to the point of being unsafe?

i guess what i'm trying to figure out is how much difference i can expect from a better bike. am i better off spending the time and money to get a good road bike that fits or will i get the most improvement in my times by more and better training on my POS wal-mart special? thanks for the advice so far...maybe the answer is obvious and i'm just dense.

Allright, excuse my smarty-pants-ness, but...


That's BS. There's no way you can say "3% weight off and your time will brop by 3%". Sure, lighter is better on accelerations and uphills, but anywhere else, it doesn't matter.

Yes it does have it's effect on keeping your speed constant. A heavier bike equals to more friction on different areas of contact on the bike (i.e. the contact at wheels and fork). It may not be a whole lot, but it's not without effect.


To make it even more confusing, the heavier person/bike will go FASTER on downhills.

Not true. Objects with different masses fall at the same speed. Recall constant gravitation acceleration of Earth? The factors that effect your speed downhill are impedeing forces such as wind and again friction on your bike.

timerigger,
I can tell you that a good bike makes a HUGE difference... But only if you are ready for it.

On my department store MTB I could maintain maybe about 19 kph for extended periods, which much effort. On my roadie I can maintain 30 kph with less effort than it took me to go 20 kph on my department store bike.

My advice is ride whatever bike you have for now (if you are at the beggining of your training). It may sound stupid, but $1000 is a lot of money... at least to me.

My old bike wasn't great, but I rode with it a lot. I tackled a lot of hills with it. Even went on a 100k+ ride with it. I did more riding with it than some people do with bikes that cost them 2 grand.

How long have you been training? Are you serious about this sport? Don't just buy cause you think it will give you miracle performance. Sure I can fly with my roadie now, but I did most of my performance training on the crappy one.

Originally posted by Amir R. Pakdel

Not true. Objects with different masses fall at the same speed. Recall constant gravitation acceleration of Earth? The factors that effect your speed downhill are impedeing forces such as wind and again friction on your bike.


Sorry, you are not correct.

http://www.sportsci.org/encyc/cyclingupdown/cyclingupdown.html




Thus, the terminal velocity is roughly proportional to the square root of the ratio of M/A. Scaling reveals that larger cyclists have a greater ratio of mass to frontal area. They therefore descend hills faster as a consequence of purely physical, not physiological, laws. Since the larger cyclist has a greater mass, gravity acts on him or her with a greater force than it does on a smaller cyclist. (Note: A common misconception is to note the equal acceleration of two different sized objects in free fall in a vacuum, and assume that the force of gravity on both is equal. The force on the more massive object is greater, being exactly proportional to mass, which is why the more massive object is accelerated at the same rate as the less massive one.) While the larger cyclist also has a greater absolute frontal area than the smaller cyclist, the difference is not as great as that for their masses. Thus, the larger cyclist will attain a greater s3 before a balance of forces results in terminal velocity.


You have expressed a common misconception.

Also, I pass everyone going downhill, they pass me going uphill. Great empirical evidence (I weigh 230 pounds and know of what I speak) :D

Boy, do I love Google. You can find ahything there!!

Ni, think you have misunderstood either me or the article.

Look here:

"Scaling reveals that larger cyclists have a greater ratio of mass to frontal area."

I didn't say anything about the size of the biker. Of course there are many factors at play. I did say the "impedeing forces acting on the bike". The article is talking about how terminal velocity on larger bikers is higher since they have "greater absolute frontal area".

We are talking about the bike here, not the person. A heavier bike does not necessarily reflect the same effects as a heavier biker.

My original statement was


To make it even more confusing, the heavier person/bike will go FASTER on downhills.

You said THAT was not correct. My statement included a heavier person/bike together.

Okay. I will make no further statement. I would suggest that a heavier bike itself, going downhill, would display the same characteristics of the ratio of mass to frontal area as a person and a bike. In fact, I think that the frontal area for the heavier bike would probably be the same as the frontal ares of a lighter bike. The difference would be in the materials and construction.

But, enough said.

how about: the bigger they come the harder they fall....
but what will really bake your noodle is: given two biker/bike totals of 175 lbs, which has the advantage (if there is one) the 150 lb'er with the 25 lb bike or the 155 lb'er with the 20 lb bike. (bikers of equal aerobic fitness)

I too have found that with my weight - 250# - and a good wheel set, there is very little effort used by me to pass most on a downhill. The opposite is true on the uphill - those that I just past are now passing me. Not too much fun pedalling 270+ pounds up a hill - it requires some extra effort. I believe anyone in my weight range will agree.
:beer:

Originally posted by ljbike
Timerigger, ask yourself this question: If the weight of the bike didn't matter, would the top athletes demand lighter and lighter equipment; even to the point of being unsafe?

What ljbike says here goes right back to the statement that bicycle weight only matters on acceleration and climbing.

Racers are constantly accelerating and climbing. That is why bicycle weight is important to them.

Originally posted by mike


What ljbike says here goes right back to the statement that bicycle weight only matters on acceleration and climbing.

Racers are constantly accelerating and climbing. That is why bicycle weight is important to them.

You can't have your cake and eat it too. If being light helps you on climbing (which it does), then it HAS to hurt on the downhills (which it also does).

Of course, since it takes longer to go up hills than down hills, the net effect of being light (going faster uphills) is stronger than the advantage gained by being heavy (going faster) on the downhills. Darn!!

My speed and accleration downhill hasn't changed as I switched from a 40lbs department store bike to a 20 lbs road bike.

In fact, it seems to pick up speed a lot faster downhill now.

Oops. I just want to declare my statement about the proprotionality of weight to speed was indeed a brain fart, a momentary lapse of reason, an offense to the elementary laws of physics, a hint as to why I only made it through freshman physics due to my roommate (who now researches string theory).

Even when discussing climbing, my statement would not be wholely correct, given that one has to calculate the slope into the whole equation.

As has been stated in other threads, aero positioning on the bike plays a much larger role than weight savings, especially in no drafting events like time trials or triatholons.

Cheers.

Originally posted by Amir R. Pakdel
My speed and accleration downhill hasn't changed as I switched from a 40lbs department store bike to a 20 lbs road bike.

In fact, it seems to pick up speed a lot faster downhill now.

You can't compare directly a department store bike with a non-department store bike. Rolling friction, quality of bearings and friction, etc.

Amir. Take my Lemond BA and get an absolutely identical one. Fill all the tubes with cement or lead of one of them. Set them both on a hill, without a rider, and figure out a way for them to get to the bottom without tipping over. Have 120 psi in all tires.

The cement-filled one will get to the bottom first.

Amir. Every time I go downhill against a light rider I prove this.

You want to improve speed. No need to buy a new bike. To improve speed immediately on your walmart-bike:

- get narrow, slick tires;
- get a timetrial bar ("triathlon" bar);


Basically this will add alot of speed without much extra costs. If you feel your biggest gear is not big enough, try a 53, 54 or even 55 teeth front blade.

If you find that Triathlon is fun and you decide to do weekly training, you can go for a road bike. But for an incidental event you don't have to spend loads of money.

Just my 2 cents,
Timo

I too am a triathlete. I did my first sprint and oly distance races last year on an old Peugeot steel frame bike. Apart from some mechanical failures due to age and component wear, the bike pretty much held up through many miles. And, yes, I passed a lot of people going down hill.

The Peugeot weighed in at 35 lbs.

This year I purchased a '01 model Giant TCR2. It weighs 20 lbs, has a carbon aero fork and seat post which add comfort mainly, and I can tell you that it is much faster. The tires are thinner, the STI shifting (Shimano 105) is way better than down tube friction levers (the Peugeot's were plastic levers that finally broke!), and the fit is excellent. Plus it looks faster, and so I feel faster, and more importantly, my wife thinks I look cool!

Most important to me in the change from a really heavy bike to a lighter, sleeker bike was that, as stated above, it takes far less effort to go even faster than what I had to put out on the Peugeot. And for a triathlete, that is vital for going into the run!

This past weekend I went back to the site of my first sprint distance triathlon and did the bike and run portion. Of course, I am in better shape this year than I was last year which helped overall, but here are the results:

I shaved 2.5 minutes off of my bike time. Conditions were terrible... windy, cold, wet... I averaged 22 mph (16 mile course) where last year during perfect racing conditions I only averaged 19.8 mph and had to walk half of the run.

The run this year?... I did 4 miles in about 30:30. Last year I walked half the course, because my legs were spent.

To wrap up, I think a road racing bike would be a good investment for you, and I think with all else staying the same, you will have a faster bike and a much more comfortable transition and run. Plus, the "looking cool" factor will make you feel that much faster, hence, money well spent! :-)

Good luck!

Does the bike matter? I guarantee you it matters. I was riding a Sears "mountain" bike. The first "decent" bike I tried wasn't even a road bike, but a a Giant Cypress "comfort hybrid". I was amazed. Compared to the Sears the Giant felt like it practically rolled by itself. And this was a $300 bike with 38 mm tires and weighed as much or more than the Sears. When I moved up a few months later from that to a true road bike I was blown away again at how much easier and smoother that was. Everything just works easier and smoother. The wheels roll better due to better bearings and smooth, narrow tires. The pedals turn more smoothly due to the better bottom bracket. Shifting is smoother. Braking is easier. You go faster with less effort or much faster with the same or a little extra effort. When you finally do it you will kick yourself for not getting a road bike sooner.

OK so how much difference is there between a $1000 road bike and a departstore mountain bike?

Well part of it depends on conditioning. I would think that a couch potato (an out of shape person) might actually go faster with the cheap mountain bike because it is more "comfy" and they are not going to be going fast enough for the advantages of the road bike to "kick in".

What will you get with the road bike?

1) Better fit in all likelyhood. This will give more comfort and more efficiency.
2) With the road bars a lower riding position that is more aerodynamic and allows higher sustained crusing speeds.
3) With the higher quality components, you will have better shifting.
4) With the lighter weight the road bike will accelerate much faster. Wasting less energy on accelerations will mean that you will get to your cruising speed faster and fell less beaten up getting there.

If you are in any kind of shape (and you must be doing a triathalon), I would think that you will average at least 2 mph faster and probably more.

So what if you went out and spent even more money on the road bike? Well, you might see a little more performance. But you get the vast majority of your performance gain when you get a road bike that one would call "decent". Going from "decent" to "superb" and from "superb" to "great" gives less and less of a performance improvement. In facts, many people don't see any performance improvement going from their first decent bike to very expensive bikes. The higher end bikes may have a better "feel", weigh slightly less which means nothing except in really long climbs, and most importantly have really cool looks to impress your friends.

Originally posted by timerigger
I just completed my first sprint triathlon using a $100 mountain bike and I'm wondering how much faster I might have been on a decent (below $1000) road bike. My swim and run times were solidly in the middle of the novice group while the bike was near the bottom.

You would have been faster on the road bike, for several reasons.

1) You on the road bike, with its drop handlebars and stretched out riding position, would have a considerably more aerodynamic profile. At higher speeds, air resistance becomes a very important factor.

2) The road bike's wheels and tires together have considerably less rotating mass, which directly affects your ability to accelerate.

3) The road bike's thin, slick, high-pressure tires roll more easily, and corner better. You'd lose less speed in turns.

4) The road bike is lighter, and that is a benefit on every turn of the pedal. Even if a heavy bike might have some theoretical advantage when going downhill, it's nothing compared to the benefit of less weight over the entire course. Friction is friction.

5) The road bike will let you transfer the maximum amount of energy into forward motion. It's probably more rigid around the bottom bracket. It has no shock absorbers. It will (or should) have a clipless pedal system. Even the energy it takes to move the shift levers will be less.

You can compete and have fun riding anything. If you want to place higher or even have a chance to win, you'll need a road bike.

RichC

Doesn't anybody pedal downhill?? Wouldn't the lighter bike and rider go faster downhill---just by going to the higher gears and having less weight and greater acceleration(sp?) to push forward with each stroke of the pedal---even going downhill????

I don't know this for sure---I'm more curious than anything.

To make it even more confusing, falling objects are also affected by the surface area of the object. A rock could weigh as mush as a peice of sheet metal. But the sheet metal has a larger surface area, which is caught by the wind, which slows it down, while the rock falls faster! Although this has absolutely nothing to do with road bikes!:)

Originally posted by OmahaRider
Doesn't anybody pedal downhill?? Wouldn't the lighter bike and rider go faster downhill---just by going to the higher gears and having less weight and greater acceleration(sp?) to push forward with each stroke of the pedal---even going downhill????

I don't know this for sure---I'm more curious than anything.


Depends on the hill. Yes, given your scenario above, it would be possible. But, on a long steep hill, you are either coasting or braking to control yourself before turns and to keep things under control, watching for rocks and sand and cars.

After a certain speed - say about 32+ mph, depending on the bike and gearing and person pedaling, you simply can't pedal fast enough to go faster. Some bikers hit 50-70 miles per hour on downhills (not I, my fastest is about 35-38 mph - I just don't feel safe going faster). But I have been passed by plenty going 45 mph+.

thanks to everyone for weighing in on this (pun intended!) i'm beginning to see the light (oh, enough already) but here's the next question...how do i know a good fit from a bad fit? is it good enough to know that since i'm 5'8" with a 30" inseam that i need a 52 or 54cm(i think) or is every frame different...in other words, can i buy a used bike online and do okay or should i go get measured at the LBS?

For your first road bike, buy localy, and get fitted by a LBS.

I think we have a post about "its not about the bike"
and it was discuss in a very lengthy manner, I think everyone agrees that the bike plays a factor, the person riding the bike, the condition when the race was done and everything if it plays in a good rythem you will go will fly

Timerigger, try this site:
http://www.wrenchscience.com

Hey guys, here's my view on the bike weight issue.

Okay, there's 3 kinda roads out there, flat, downhill and uphill. So, there is the advantage for the lighter uphill-er and the advantage for the heavier downhill-er. So won't the advantages cancel out each other more or less?

So there comes the flat road. Here is where acceleration is more important. The lighter bike with the lighter cyclist will definitely win the race more easily than the heavier bike with the heavier cyclist.

Thus, my conclusion is that people do choose lighter bicycles for a reason, to win the race!

The following article (already cited in this thread) makes the argument that, no, the uphill and downhill segments do not cancel each other out. Rather, since cyclists need much more time to go uphill, the time gains on the uphill are more significant than the time gains on the downhill. This is why one must be at least a good (if not excellent) climber to win a race like the TdF.

http://www.sportsci.org/encyc/cyclingupdown/cyclingupdown.html

The article has some interesting things to say about energy expenditure on uphills and resting on downhills. It's pretty intuitive.

Cheers,
Jamie

Well whether you should buy used or from an Local Bike Shop ,LBS, is up to you. If you are a real "gear" head and quickly pick up technical stuff, you can probably do OK with a used bike. A good used bike costs about 50% of a new bike. But you have to know what you are doing.

For 99% of the people, I think going to a good LBS is the way to go.

One of the people out there thought that light cyclists on light bikes won on flat roads. Au contraire, mon cher (all the french I know). On flat roads, acceleration is trivial. I mean how long does it take you to accelerate to 25 mph? You spend most of the time maintaining a constant speed. At speeds over 20mph, you are spending most of your energy against air resistance. If you take a big strong cyclist and compare to a small strong cyclist, sure the small strong cyclist will have less wind resistance but the big cyclist will have only a little more wind resistance and much more than enough horse power to make up the difference. On climbs, the small cyclist wins because they have a better power to weight ratio then the big cyclist. This is why tandems do so well on flats cruising at high speeds - twice the weight, twice the power and just a bit more wind resistance.

I don't think anyone has mentioned gearing. There is a big difference between road and mountain, to maintain speed.

I think I gaind 3-5 mph just changing bikes.

Originally posted by Timo
You want to improve speed. No need to buy a new bike. To improve speed immediately on your walmart-bike:

- get narrow, slick tires;
- get a timetrial bar ("triathlon" bar);


Basically this will add alot of speed without much extra costs. If you feel your biggest gear is not big enough, try a 53, 54 or even 55 teeth front blade.

If you find that Triathlon is fun and you decide to do weekly training, you can go for a road bike. But for an incidental event you don't have to spend loads of money.

Just my 2 cents,
Timo

I have to disagree strongly with this suggestion. Attatching a tri-bar to your MTNBK won't make that much of a difference. In fact, it will change the weighting drasticly and alter the way your bike handles making it harder to control.

I started training for this season tri series last September on a department store mtn bike. I really wanted to get a road bike for lots of reasons including the ability to join in and hang with the local group rides.

After a month or two of research I purchased a Giant OCR 2. The difference is amazing. I noticed an immediate 3-4 mph increase over the same course.

If you are considering doing more than one triathlon a year and train on a regular basis, investing in a good road bike is a wise choice IMHO.