Al.canoe

I posted on a previous thread the question of how much faster I might go with a sportier bike. I stumbeled on the answer. You guys who posted were right on. I found a speed/power calculator (see https://www.kreuzotter.de/english/espeed.htm). Powering my 32 lb touring bike in the drops at 14.8 mph, spinning 90 RPM, 50 ft altitude, level ground and robust wide touring tires with tread requires 120 Watts.

The effective drag area is 4.2 sq feet. So working backwards I found that theoretically at least, I'm generating 120 watts: one lightbulb worth. Kind of depressing to look at it that way.

The drag area is not going to be affected much by a race bike, it's due mostly to me. So it's going to more a function of weight and road friction. I plugged in 22 LBS for the race bike (vice 32 for my tourer) and went to high pressure race tires and the speed went to 16.3 mph. A delta of only 1.5 mph.

With a 5% grade and 120 Watts, it's 4.6 mph and 5 mph. A delta of only 0.4 mph, but almost 8%: significant on a percentage basis, but I'm in no hurry as I'm retired. Plus I like to climb.

If one can generate enough power to cruise at 25 mph, the race bike would have much greater superiority because the friction losses are greater at high speed. Lance needs his race bike.

Since my tourer has a beautiful lugged frame and gracefully curved fork and I like the comfort, I'm leaning towards sticking with it and just upgrading a few things. Looks like the fenders aren't that big a deal (compared to 4.2 sq. ft) as far as drag is concerned. I like fenders. I even use them on my mountain bike.

My new $1600 list price-range full suspension mountain bike will keep me entertained with the "new bike" motivation for a while. A big step up in comfort and technical hill-climbing ability for me. I may just casually look for a good used road bike that fits well.

Al

fogrider

Al, interesting...but I think your analsys is flawed. Your calculations maybe corrrect, but first off, a sporty bike is not necessary less comfortable than a touring bike of old (you didn't say how old your touring bike is, but at 32 lbs, I will assume it is more than 10 years old.) The key to long rides is good fit and that means comfort. With carbon forks/seatstays, ti frames, and sti or ego shifting, comfort is the unsaid secrect.

Lighterweight also means more responsive handling and faster accelleration. You maybe retired and in no hurry, but if you ride a lot, I'm sure you will appreicate handling and accelleration. I was on the tandem this weekend, and its fun to ride it, but the handling a low speed is no fun. Once it was up to speed, it is increadible, but at low speed, I really feel the weight of the bike. Your old touring bike might be very well balanced, but compared to the new racing bikes available today...I assume you've ridden some of the new bikes...you must know what I'm talking about.

miamijim

For a comfy racer find a Trek Y-foil. I just bought one over the weekend...ultra comfy and very fast...Lance rode one in the tour TT a few years back....

Al.canoe

I don't think my analysis is flawed, at least not anymore than the limits of a simplistic model. Possibly what you might find flawed is my lack of interest in light weight and acceleration. The issue of acceleration and the comfort of the newer bikes was addressed in the original thread ( More "sporty" bike mean more speed?).

Actually the bike is nearly 20 years old. The fit is great. For the speed model, I adjusted the weight of the bike and myself to accommodate what I carry. Stuff like 6 to 8 LBS of water (it's hot in N Florida), hydration pack, rack, pack, first aid kit, some tools, a jacket to match possible conditions, cell phone, FERS radio (sometimes) to talk to my wife somewhere behind, food, tube, pump, maps, map holder and sometimes a bike lock. If I need to shed pounds, I'll just lose another 5 LBS. to add to the 20 I've already shed.

I pretty much stay on rural roads, so I don't really need to accelerate that much. Plus, I'm not leaving the gear behind, so a few pounds less bike is not all that significant for what I do and I climb some too. I bike in various places like Canada and the Southern Mountains. I've already got STI by the way and nice Ritchey bars with those nice ergonomic drops.

Where I really appreciate handling and acceleration is off-road biking.

Al

fogrider

Al, your analysis of horsepower to speed is correct, but I think that a touring bike if for touring. If you're looking for speed, 1.5 mph may not sound like much, but it does mean that in an hour you would be a mile and half further down the road...I think that is significant. Admittedly, there is no way to get around the water, but with today's mini tools, I carry every allen wrench I need and a chain tool combo and a truing wrench tire tools, pump, and not much else. On the tandem, I even carry and extra tire.

In San Francisco, I like to wear a ploypro long sleeve under my jersey arm warmers over a jacket (easy to pull off parts to adjust to climate and no flapping from the jacket). Never need a lock (never leave the bike unattended).

My schwinn paramount was built in 1964, which I love and was on this past sat., but my kestrel is also a joy to ride. And if you ride by yourself, accelleration may not be important, but if you ride with friends in a group, it comes in handy...and its just fun. Offroad is fun in a different way, flying down the road in a group rotating pulls at 25+ mph is unmatched!

Croak

Effective drag area will change with relation to riding position. The whole idea behind a road bike is to mount you in an efficient position, aerodynamically speaking.

Al.canoe

I'm as low as I'm going to ever get with my Ritchey ergo drops, Croak. It's the comfort thing. Matter of fact, when/if I get a racier bike, I'm putting the same bars on it. It's taken years to get my bikes set up the way I like them. Same for the canoes, by the way.

Al

Croak

Well I think that answers your question then.

When you said 'sportier bike', it immediately means more race specific geometry leading to a more agressive, aerodynamic position. The weight itself will not prove to be that much of a difference in average speed but rather handling and general 'feel'. This would come in to play when riding in large groups and trying to hold wheels, but not so much in laid back touring.

Al.canoe

Croak, you make a good point. I'm really comparing a sporty-rigged touring frame+fork with a race bike. That's why I described the bike in the original post (even to the tire size/pressure) and believe that the simple model gives a reasonable answer. It's also consistent with observations of many of those who commented.

For the fun of it, I'm going to put on narrower, high pressure tires. The model indicates that I should gain about 80% of the delta. I don't know how the model's tire relates to mine, but it'll be interesting. A possible result is that my touring frame will transfer more road shock with high pressure tires than the newer race bikes which are designed for hard tires. Now there's an interesting issue.

Al

TXCiclista

THAT is a cool site!

Croak

I was going to mention new tyres, and to a lesser extent, new wheels. I think you will find the greatest gain against the smallest hinderances.

That website is a good tool but there are so many variables, I could pick it to pieces all night! Brings back my days of picking economic models to pieces...

TXCiclista

Maybe so, but it certainly helps those who don't know all the physics. I guess you couldn't come up with a perfect site because no one would want to spend time finding all the variables. I can just see it :

"Please enter: height, weight, general area of upper torso, frontal are of left leg & right leg, body fat percentage, relative force of exhaled breath, etc, etc, etc"

Ah well, I'll just continue being clueless. It's at least better than nothing

shokhead

I can only get so low.

shokhead

Nice site.

TXCiclista

The link's in the very first post.

Al.canoe

What I did was work back from my known performance. I typically cruise at 15 mph at 95 rpm cadence. I just left the model at 90 rpm (default), input 15 for speed, and told it I was in the drops, though I do 15 on the hoods. The model will tell you frontal area and power. I then changed tires, slope, wind speed, etc. with the power and area of the initial run. The model will not change the power or frontal area, but sometimes it changes the bike weight back to the default value when you change other parameters. So you need to double check that before you execute.

Al

Croak

You forgot the Moons' alignment with Venus