December 16, 2012
Steel Bike Weighing 9.6 lbs More Than Titanium BIke Climbs Just As Well!
onTechnicalSteel Bike Weighing 9.6 lbs More Than Titanium BIke Climbs Just As Well!
Did I get your attention with that headline? It was inspired by an article I read in the most recent issue of Bicycle Quarterly, a fantastic, niche magazine published by Jan Heine.
In this issue, Jan tested a titanium bike against a steel randonneur bike. It was a real world test: two guys racing each other up the same hill, one on the ti bike, one on the steel. They swapped out the bikes several times. Both were evenly matched in terms of strength, endurance and weight.
The weight of a steel bike is always of interest. This steel bike was 9.6 lbs heavier than the ti bike, but it climbed as well. It sounds implausible, but as Jan explained, when the weight of the riders was taken into account, the steel bike plus rider was only 5% heavier than the ti bike plus rider, but the steel bike “planed”, helping the rider generate the extra power needed to overcome the weight difference.
Fans of Jan’s bike testing will know there is an advantage to a bike that “planes”. This is a bike that is in synch with the rider and flexes in a way that “gives back” some of the rider’s energy to the drivetrain.
Just for fun, I backed through Jan’s math to calculate that he weighs about 175 lbs. I used my own 100 lb. weight in his calculations and found that the difference in weight plus rider for me is about 8%. Ah, we smaller riders have a rougher road to ride, do we not? A bike that planes is a must!
The important point is that weight is not a big deal. Choice of tires and construction of the frame is though.
Take the road less traveled — not only on your bike, but in your reading as well.
Worn Bicycle Chain and Cassette
Question of the week: “This past May I bought a hybrid bike. Now, at 2300 miles, I already need a new cassette. The bike shop said it’s all the miles I put in. How many miles can a cassette take?”
A cassette can take a lot of miles. But how many depends on how much care you give your chain. There’s this myth that when you replace your chain, you should also replace your cassette. That’s only true if you’ve really worn your chain out. The pins that connect the chain links wear over time, causing your chain to get longer. After a while, the shifting gets sloppy and inefficient and the chain starts to deform the cassette cogs and the chainrings.
The trick is to replace the chain before it gets too worn. You can purchase an inexpensive chain gauge which lets you check the wear of the chain. By replacing the chain before it reaches the “replace” point, you can continue to use the same cassette. Everything is expensive these days, but replacing just the chain is a lot less expensive than replacing the chain and the cassette.
So, the name of the game is to keep that chain going for as long as you can. That means cleaning it and lubricating it properly. The rider who sent in this question admitted to riding in the rain a lot and not paying much attention to her chain. Both the worn bicycle chain and the worn cassette died an early death. I’ve ridden the same cassette over 10,000 miles by caring for the chain and replacing it twice.
Note: The chain gauge shown here is no longer made. But check out Park Tool’s CC-3.2 Chain Wear Indicator. It’s inexpensive and works well.
Lugged Frame or TIG-ed frame?
By default, the bicycles shown on my site are TIG welded. Even though you may see this kind of construction almost exclusively these days on both steel and aluminum frames, you may not have know what it’s called. Here’s a photo of a Coto Doñana Vagabond showing a TIG joint — seat tube, top tube and seat stays.
Example of TIG welding
But another way of “putting the tubes together” is with lugs. Lugs are sleeves that hold the tubes in place. Brazing rod is melted into the sleeve and becomes a very strong “glue” that holds everything together.
A head tube lug
Is one method better than the other? It just depends on your preferences. Aesthetically, a lugged frame looks classy and elegant. With some creative filing and cut outs, lugs can become works of art. If you’re thinking about purchasing one of my bikes and want lugs, I’ll be glad to oblige. They are well worth the extra cost.
Structurally, either method is fine. Typically, a TIG-ed frame will weigh a little less because it has no lugs. In theory, the “butts” (more wall thickness at the end than the middle of the tube) can be a little bit shorter since heat from TIG welding is more localized. With a brazed, lugged frame, the heat spreads over a greater length of the tubing, so the butts may be longer. Longer butts add weight.
Lugs typically come in set angles, so this may an issue if the frame design calls for something unusual. Since TIG-ed frames don’t use lugs, any frame angles will work.
In an upcoming post, I’ll talk about the “miracle” of lugs, tubing and brazing rod.
What I’m Reading: Just Ride by Grant Petersen
Cyclists are bombarded with information: advertising, in-ride chats, blogs, tweets. Sometimes we spend so much time making sure our kit looks good, our bikes look good and our pre-ride stretching was done that we forget we’re here to Just Ride the bike! Sure, there is a certain amount of fun toting up the miles on the mileage chart, planning the details of what variety of Gu® is going in the jersey pockets, making sure we look like “real” cyclists and not getting dropped on the first hill. But the bike is such a darn simple machine. Quiet, unassuming, but always ready to take us on an adventure.
Grant Petersen, founder of Rivendell Bicycle Works and former U.S. marketing director for Bridgestone Bikes, turns off the marketing blather, gives us a shake of the shoulders, looks us in the eye and says, “Let it go. Get back to basics.”
If just one image comes to mind after reading his book, this is it:
Grant’s book is a collection of short essays. Flip it open to any one of them and start reading. You’ll agree (although sometimes begrudgingly) or disagree with just about everything he says. What do I mean? Here’s a selection of chapters:
The weight ruse
Racing ruins the breed
Bags, not armloads or sweaty backs
Pumps, not greenhouse gas
Drink when you’re thirsty, not before
Surprise: fabric doesn’t breathe
I had a ball reading this book. Grant is so … down to earth. He takes us back to a kinder, gentler world of bicycling — one that’s pretty much been lost in today’s whirlwind of faster, lighter, stiffer. Every cyclist will relate to this book — love it or hate it, but you won’t be able to put it down.
The Details:
Just Ride by Grant Petersen
Workman Publishing
ISBN 978-0-7611-5558-4
The thrill of meeting your new bike!
Saturday morning was a very special one. A Georgena Terry Coto Doñana Tour was about to meet its new owner. The scene: Sid’s Bikes on West 19th Street in New York City.
Larry Wallach, Sid’s manager, carefully hung this sweet machine ‘way up high so nothing would happen to it.
Making sure every story has a happy ending comes down to working closely with the customer and the shop. When you purchase a Terry, I include a free fitting by the dealer to make sure everything is dialed in perfectly. Sid’s is the best. If you’re in New York City, this is the shop!
From the looks of things, I’d say the bike and rider bonded immediately.
Hearing this after the maiden voyage made my weekend:
“I really can’t thank you enough for this bicycle! Between providing such an amazing ride and its beauty, I’m sure I’ll always be excited to get out and ride. Even the process of working with you on it was so pleasant. It’s been an incredibly satisfying experience to finally meet and ride it!”
My goal is for every Terry customer to feel this way.
September 5, 2012
A Reader Asks: “How narrow a tire should I use to get a benefit from lower rolling resistance?”
onTechnicalA Reader Asks: “How narrow a tire should I use to get a benefit from lower rolling resistance?”
Tires are one of the most fascinating aspects of the bicycle. They can make or break the comfort and efficiency of the ride.
Common sense used to have it that the narrower the tire was and the higher the pressure in the tire, the lower the bicycle tire rolling resistance would be. Which led us all to run the narrowest tires we could find with the pressure pumped to the max. Assuming you were riding on roads as smooth as glass, that might have made sense.
Truth be told, all things being equal (like pressure and tire construction), a wider tire has less rolling resistance. Huh? How can that be? Well, it’s all about the physical deformation of the tire. It’s that deformation that causes rolling resistance. When more of the tire deforms along the circumference of the tire, rolling resistance increases. Maybe a picture will help. Here’s how the patch size is determined. Imagine the bike tire is on a sheet of glass. You’re looking up from beneath it:
Here’s an exaggerated view from the side:
Now, some people really don’t want to give up their narrow tires for wider ones. I mean, it just wouldn’t look cool. So, the makers of bicycle rims have come to the rescue — they are now making wider rims! This allows the tire to “relax” (as in, “aahh, that feels better”), which makes the contact patch shorter and wider, just what’s needed to reduce rolling resistance.
Another source of rolling resistance comes from rough road surfaces. With the pressure pumped up to the max, the bike bumps around and its forward motion is hindered. Solution: lower the tire pressure so the tire works as a shock absorber, reducing these “suspension losses”. Jan Heine has a neat blog about some testing he did to find out how much more power a cyclist exerts to overcome the bumps.
The Gale Force bicycle uses Velocity’s A23 rim for just this reason. With a wider rim like this, not only is the contact patch optimized, but the tire can be run at a lower pressure so it absorbs road shock. This is because the tire’s sidewalls don’t distort as much as they would with a narrower rim, hence, the tire is a little “taller” and less prone to pinch flats.
Short Reach Brakes versus Long Reach Brakes
The best part of designing bikes is coming up with solutions. Often this comes about from an offhand comment from a rider. When I hear it, I realize I can bring more to the bicycle design than either of us planned on originally. Here’s an example. I recently built a Georgena Terry Gale Force bicycle for a rider who mentioned that the roads in her area were really rough. Steel bikes are great at absorbing road shock, but a wider tire can help as well.
The problem is that a traditional road bike uses a “short reach brake”, which may limit the width of the tire that can be used. It’s often not possible to use tires wider than 25mm (1 inch) with this kind of brake. As the tire gets wider, it gets taller. And there’s the rub — literally. The wider tire is too close to the underside of the brakes. Imagine picking up a small stone and having it jam between the tire and brake. Not good.
“Long reach brakes” solve this problem. The arms of the brake are about 8mm (.3 inch) longer than the arms on short reach brakes. If a bike is specced with this brake, the rider can use wider tires. So when my customer mentioned rough roads, I offered her the option of long reach brakes so she could put wider tires on her bike. A simple solution that added versatility to the bike. Unfortunately, you can’t just swap out your short reach brakes for long reach brakes to solve this problem. The bike has to be built for one style or the other.
Does a Small Front Wheel on a Bicycle Make You a Slow Rider?
One question I commonly hear is “Will I go slower on a bike with a small front wheel?”
The quick answer is “no”. Suppose we have two identical bikes, one with a 24″ front wheel and a 700c rear wheel and one with 700c wheels front and rear. If the gearing on the two bikes is the same, then one turn of the pedals will turn the rear wheel on both bikes the same amount and the two bikes will travel at the same speed.
It is true that smaller wheels have more rolling resistance because when the tire deforms under the weight of the rider, more of a small tire’s circumference will deform than that of a larger tire. But this resistance is tiny and not significant. A smaller wheel rotates more rapidly than a larger wheel, but it weighs less, so maintaining its momentum really isn’t an issue either.
So, if you ride a bike with a small front wheel and you feel slow compared to your friends, consider some other reasons why that might be the case. Perhaps they’re stronger than you are — not unlikely when comparing a man to a woman. Perhaps your bike doesn’t fit properly. Or maybe their bikes are substantially lighter than yours; this is more likely to have an effect during rides in hilly rather than flat areas. And then there’s always the psychological side: if you think you’re fast, you are!
What Size 24″ bike tire do I need?
I get lots of questions about understanding and sourcing 24″ tires and tubes. We use this size on our smaller bikes. Here’s all you ever wanted to know about the 24″ size. And if it’s not — leave a comment and I’ll be glad to help.
First, let’s talk about tire designations. 24″ is a very broad term. It’s best to refer precisely to the tire/tube size. This is done by referencing the bead seat diameter — the diameter of the tire’s bead, which rests inside the wheel rim.
You can tell what tire size your bike uses by reading the impressions on the sidewall of the tire. Typically, they will look like this: XX-YYY. The first two numbers are the width of the tire in millimeters and the second three numbers are the bead seat diameter in millimeters. This applies to all sizes of tires, not just 24″.
For instance, if your sidewall reads 25-520, your tire is 25mm wide (about an inch) with a 520mm bead seat diameter. Armed with this information, you can order the correct tire/tube for your bike.
This tech page from Schwalbe explains much more about the size markings on tires.
Terry has used two 24″ road sizes — 600A, with a bead seat diameter of 541mm and 24″, with a bead seat diameter of 520mm. The 541 size was used very briefly on only one Terry model — the Precision — for a limited time in 1985 – 1986. Later Precisions and all other Terry road bikes which are built with a 24″ front wheel use the 520 size.
Terry hybrid/mountain bikes using 24″ wheels front and rear have a 507 bead seat diameter.
ROAD BIKE TIRES/TUBES
Most Terry bikes use 24″ wheels with a 520mm bead seat diameter.
Sources:
Terry Bicycles carries a variety of 24″ (520) tires/tubes which can be found here.
Your local bike dealer can order 520 tires/tubes from Quality Bicycle Products, 800-346-0004 (wholesale only).
Here is a list of some 24″ tires that are available:
Panaracer Pasela 25-250
Terry Tellus 32-520
Schwalbe Durano 23-520
Older Terry Precisions used a tire size popularly called “600A”, which has a 541 bead seat diameter.
Source:
Schwalbe RightRun 25-540 (part number 10282387). More information available here.
The Schwalbe RightRun comes closest to the Wolber Rallye 22mm tire originally specced on the Precision. The fit is quite tight (because it’s 1mm smaller than the original Wolber), but it will work. Schwalbe also carries presta valve inner tubes (part number 10519213) which can be found here.
HYBRID BIKE TIRES/TUBES
Tire Source:
Schwalbe Kojak 40-507 (1.5″ wide). This tire is a slick, but rides beautifully! Unless you’re on gnarly roads, it’s the best. – Information can be found here.
Schwalbe Marathon Plus 47-507 (1.75″ wide) A very robust tire. Not light, but bomb-proof! – Information can be found here.
Inner Tube Source:
Schwalbe offers a variety of 507 inner tubes with either presta or schrader valves — AV10 and SV10. See here for more information.
REPLACEMENT WHEELS (520 or 507 size)
Do you need a replacement road or hybrid wheel? You or your dealer can obtain these from Velocity USA (800-453-6126). Velocity supplies all the wheels for my hand-built bicycles.
Gobsmacked! Weight and rotational inertia!
I’m “gobsmacked”, as the Brits would say. A few weeks ago, I took a week off to ride my bike. In place of my Coto Doñana Tour, I rode a vintage lightweight steel bike with 650c wheels. For this trip, I wanted a bike that was a little lighter and livelier. And indeed it was livelier — with every punch of the pedals, the bike leapt forward. Amazing what a light ride can do for you.
Or can it? Upon my return home, I weighed both bikes. Gulp…my prized 650c bike is a full pound heavier than my Coto Doñana Tour . Okay. How about the wheels? They’re the same weight even though the 650c bike uses Schwalbe Ultremo 23mm tires and the Tour uses Panaracer T-Serve 32-559 tires. This doesn’t mean the wheels have the same rotational inertia, though. Intuitively, my guess is the 650c wheels have less inertia. But is it enough to account for the “suppleness” of the 650c bike? Or is this a case of mind over matter?
About the same time I was pondering this, Velo magazine’s tech editor, Lennard Zinn, ran a column answering a reader’s question about the importance of bike weight. That has since blossomed into quite a discussion on the topic, taking many interesting twists and turns. How important is frame weight? How important is wheel weight? What about the weight of the rider??? I’ve referenced links to these articles at the end of this blog.
It’s hard to really summarize the discussion since so much information was shared. But the gist of it went like this: weight is important, but maybe not as important as we’ve been led to believe. If you generate x watts of power going up a hill, those x watts will get you up the hill faster on a lighter bike. How much faster? It depends on the weight of the two bikes. And let’s not forget the weight of the rider — the amount of power a light rider can generate is typically less than that generated by a heavier rider. So what’s the tradeoff in weight and power generated? That’s where it starts to get a little murky. And…the biggest factor: how well does the bike fit? Do you think that has a role to play in your power output? You bet!
Wheel weight falls into its own little piece of the puzzle. We all know a wheel is harder to accelerate when its mass is further outboard ( think “flywheel” for the ultimate hard to get started wheel). In physics terminology, a wheel with more “rotational inertia” takes more oomph to get started than a wheel with less rotational inertia. But how much? Marketers like to think it’s a lot, but physicists aren’t so sure. At least not in the general scheme of things.
No one does a better job of not mincing words than Jobst Brandt when it comes these matters, so I’ll let him have the last enticing thought: “Although it seems daunting, when another rider pulls away on a hill…, these accelerations, except in standing starts, are so small as to make the rotating mass story a hoax.”
References:
Does Bike Weight Matter?
Does Wheel Weight Matter?
Wheel Inertia
Jobst Brandt: The Weight Question