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A little more about tires and rolling resistance

Bicycle Rolling Resistance is a website run by Jarno Bierman in the Netherlands.  Jarno* uses a roller to measure tire rolling resistance.  The attraction of Jarnos’s work is that he uses a consistent method for a large number of different tires, and he uses a textured roller in an effort to account for energy loss from vibration as well as tire flex.  The consistent test procedure gives me more confidence in his results than I have in roll-down test of just a few tire models, and the textured roller presumably approximates a real-world road surface better than a smooth roller.

However, he focuses on a narrow range of road tire sizes, staying close to 25 mm width. He treats stouter touring tires as a separate class, and he sticks to tires of around 37 mm for that group.  Road and touring tires are all 700c.  He has not yet directly explored the characteristics of wide light and supple tires.

He has, however, compared the rolling resistance of a particular model of high-performance road tires in different widths and concluded that the widest (28 mm) had the lowest rolling resistance (conti GP link ) .  And he performed a similar test with a touring tire, showing that the 37 mm tire had lower rolling resistance than the 40 mm or 47 mm tire, while the 32 mm version had the highest rolling resistance for this tire model (Marathon link ).

However, the real outlier is in the mountain bike category.  I am a little dubious of the usefulness of this test on knobby mountain bike and fat bike tires (since the knobs are larger than the roughness elements on the test roller — it seems to me that a more pertinent test would involve a rougher roller**), but the relatively smooth tires in this category should behave like road tires.

The best-performing tire in the mountain bike class  has a rolling resistance that is competitive with the best 25 mm road tires, even with each class at inflation pressures appropriate to their widths.  As one might expect, it has a very light tread and casing but measures 47 mm wide.

These results seem to show that wide/light/supple tires can be as fast as their proponents claim.  Jarno has a long list of tires that he wants to test and not a lot of capacity to do the testing, but I would love to see him test some performance-oriented tires in the 38 mm range.

crr_chart

 

*I understand that you go straight to first names in the Netherlands rather than referring to someone with an honorific (e.g. Mijnheer Bierman) as you might in English.  I prefer that informality, but I don’t want to sound disrespectful, and I apologize if I am incorrect.

**I think it might be useful to test tires on a series of rollers with different size roughness elements, comparable to Nikuradse’s experiments with pipes.  This additional experimental data might provide some insight about optimum tires, width, and pressure for different surfaces.

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Fenders: Thoughts and Experiences

The default bicycle in the US market is the racer-wannabe sports bike. This follows from the  paradigm that any weight added to a bike beyond what is absolutely necessary in competition is outside the norm.  As a result, a lot of the bikes that people own are built for that single purpose and are unsuitable for anything but sport riding, preferably with a motorized support vehicle, and the general public is convinced of the impracticality of using bikes for utility purposes.

I think this is backwards.  The minority paradigm, and the one that I would like to see become dominant, is that a bike is a tool for transportation that can also be used for sport, recreation, and adventure.  The default should be a bike with safety and comfort features similar to other serious transportation, e.g. lights, fenders, and some means for carrying stuff.  Any decrease in functionality from removing these features should be outside the norm, just as it is to remove these from a car.   This would not eliminate fast or sporty bikes, and in fact, the performance difference between a stripped-down bike and a fully equipped bike can be small.  It is much easier to ride fast on a complete bike than it is to haul groceries on a single-purpose sport bike, and the conditions suitable for recreation and adventure expand dramatically with adequate equipment.  Even the tiny fraction of cyclists who actually race are safer and more comfortable with these features while training, and can get in more miles if they integrate routine transportation on a practical bike into their training.

Fenders are an integral part of the transportation bike primarily because they make it practical to ride in less-than-perfect weather.  Riding in rain does not necessarily become pleasant, but the rider need only worry about, and dress for, what comes from the sky.  There is a wider range of  rainfall rate and temperature in which the wool jersey is all that is needed to keep you comfortable.  Both the rider and the moving parts of the bike are shielded from water and grit from the road.  Fenders keep the bike and drive chain cleaner even under dry conditions.  This comes at a modest cost.  Aerodynamics suffer little, if any, according to wind tunnel tests (Bicycle Quarterly, Volume 6 number1).  Weight reduction, if the fenders were removed, is around a pound, or about 0.5% of a 200 lb bike and rider combination.

In a marketplace ruled by the transportation-bike paradigm, most bikes would come from the factory with fenders installed.  In the real world, we are stuck with aftermarket afterthought fenders; the only exceptions are city bikes and custom rando bikes.  I worked my bike shop days (1977-1987) in towns that took transportation cycling pretty seriously and I installed a lot of those retrofit fenders.  In those days, the basic fender was the British-made plastic Bluemels, with German ESGE fenders as the premium choice.  Bluemels were mostly white or black but were sporadically available in other colors.  ESGE fenders consisted of a layer of aluminum foil sandwiched between layers of clear plastic, so they were silver colored (thus the name Chromoplastic).  Nearly all bikes in those days were designed with enough clearance for fenders, and the hardware was designed so that installation was pretty easy for most situations.

Plastic fenders have a finite life.  Bluemels did not seem to be as tough as ESGEs, and the Bluemels also tended to oxidize and get more brittle with age.  The metallic-colored Bluemels were brittle and fragile out of the box, but an appropriate color did look sharp. My last set of ESGE/SKS fenders was purchased in about 1987 and lasted 10 or 12 years, and on the order of 10,000 to 20,000 miles.  Their life was extended a couple of years with judicious hole-drilling at the ends of cracks and the deployment of zip ties.

Plastic fenders are still the most common aftermarket option.  According to their web site, the German company SKS bought out Bluemels in 1983 and ESGE about 1988.  Bluemels are gone, but SKS still makes Chromoplastics very similar to the old ESGEs, and they are readily available at bike shops and on the web.

Planet Bike fenders are also easy to find.  I have no personal experience with them, but at least some people have found them to be very durable, and I have heard good things on the boards.  There are a few other brands of plastic fenders available, but I have not seen them in shops.  I would like to check out the Somas.

Metal fenders, either stainless steel or aluminum, are much more readily available now than they were in the past. They should last longer than plastic fenders (though everybody does not agree with that assessment ). Metal fenders can be noisier than plastic fenders, picking up road vibrations and clanking with object thrown off by the tires, and metal fenders are more prone to rattling.  They can look really good, in a traditional art deco French-bike way.  The bike shops I frequent do not stock them, but they are happy to order them, or they can be ordered several places on the web.

The big players in the small field of metal fenders are Honjo (aluminum) and Berthoud (stainless steel).  Both brands are intended for installation on a bike with threaded attachment points at the brake bridge, chainstay bridge, and fork crown, as well as eyelets on the dropouts.  Even with these frame features, drilling holes in the fenders and careful fitting is required; if any of these features are not included on your frame, you may have to fabricate or purchase additional hardware.  This can be challenging. Recently, Velo Orange has stepped in with both aluminum and stainless fenders in a variety of sizes and styles, along with helpful mounting hardware. 

I have 2 bikes with Berthoud stainless fenders.  On the commuter bike (a ’74 Schwinn Sports Tourer), I bolted the front of the rear fender to the tab on the chainstay bridge/kickstand bracket.  Initially, the bike ran a roller brake on the 7-speed internal-gear hub, so the brake bridge was not being used for a brake and I drilled a vertical hole through the bridge to mount the fender.  Dissatisfaction with the roller brake prompted me to mount a caliper brake, at which point I bolted a bracket to the fender scrounged from the old front Chromoplastic.  The front fender used a “silent block bolt”, which consists of a bolt with a long head with a hole that the front brake mounting bolt goes through; the threaded part of the bolt extends downward through the fender and is secured by a nut on the bottom of the fender.  There is a rubber washer to prevent rattles.  This worked fine with a 32 mm tire, but the bolt and nut extended far enough that it rubbed on a 35 mm tire.  I removed the sbb and installed a VO sliding brake bridge bracket (normally used on the back), and that worked fine.  These fenders have held up well for 7 years and almost 12K miles of daily commuter and utility abuse.  I have some occasional tire-rub issues, but that is because I am running the biggest tire that will sort of fit.  Not surprisingly, the fenders do look a little battered.

The touring bike has threaded mounts on both back bridges.  This bike has cantilever brakes, and the front rack mounts through the fork crown.  Installation of the fenders on this bike was pretty easy, and the silent block bolt attaches to the front rack and leaves plenty of clearance.  I also mounted the front of the fender to the rack so that it could not flap around.  I have ridden 5K miles or so since installing these fenders, with no rattles or rubs.

The Early has VO anodized aluminum fenders.  These fenders come with some of the holes pre-drilled, a bracket mounted on the front fender, and a sliding bracket to connect the rear fender to the brake.  The frame had a threaded mount on the chainstay bridge.  For the pre-paint mock-up installation, I used the sliding bracket, but I could not get it tight enough to stop rattling.  The front fender uses the pre-installed bracket, though I had to cut it down a little to get it to fit.  Before the re-paint, I brazed a water bottle mount to the bottom of the brake bridge, which eliminated the sliding bracket (and it works fine on the front fender of the commuting bike).  These VO fenders have an anodized finish, which has a somewhat rough/porous surface that is impossible to keep clean and difficult to clean once it gets dirty.  However, it is a great surface for painting.

These fenders make a lot of noise when the tire throws off debris.  I have also had a lot of problems with rattles, even with liberal use of leather washers.  I tried everything I could think of to quiet one particularly loud rattle, and finally discovered that there was a crack halfway across the fender.  I do not know if this is common with this particular model – maybe the anodizing makes them brittle – or if aluminum fenders in general are this fragile.  I probably contributed to problem with an extra hole drilled for the brake bridge (I did not line it up right the first time).  In addition, the brake spring made contact with the fender, putting some additional stress on that area and probably causing or contributing to the rattle.  Perhaps coincidentally, the anodized fenders are no longer listed on the VO web site.  

The crack

I did not want to try to return them or toss them since they were painted to match the frame, so I patched the crack with strips of sheet metal, pop rivets, and a little epoxy for good measure.  I also replaced the rear brake with a Weinnmann center pull which has significantly more clearance for the fender (and by the way, it stops as well as the Galli sidepull).  This fixed the big rattle, at least for now, but there are still small rattles that I have failed to cure.  This bike does not currently have a rear rack, and I am thinking about adding one that I can connect to the fender for some more reinforcement.

The fix

Part of the cause of the crack may be the single mounting point between the stays and fenders for the VOs, which allows the fender to pivot around this point and flop around; the Honjos use two eyebolts.  This issue is discussed in this post in the Fuji Otaku blog.  I think a better solution is the two-bolt flat connection on the Berthoud, which has the rigidity of the two-bolt Honjo-style mount and does not stick out as far.

Finished product

In summary, plastic fenders still have some things going for them, including availability and easier installation.  In my experience, stainless steel is probably more durable, but plastic can last long enough that the difference may be moot.  I am not yet convinced that aluminum is a good choice.

By the way, whichever fenders you end up with, buy them wide enough — at least 10 mm wider than the widest tire you will ever put on your bike.

VO Front stay/fender connection

Stay/fender connection on Berthoud fender

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The Spring of my Discontent

This year, April really is the cruelest month.  The weather is great, early flowers are out, trees are budding, but I can’t ride.  It hurts to see other people on their bikes while I am confined to a car.   I am missing the unfolding of spring in the East Tennessee countryside.

Trillium

The trilliums are thinking about flowering

It has been a little over 6 weeks since surgery, and according to my doctors, my sternum is not yet healed enough to trust with the vibrations, potholes, and other vicissitudes of riding.  I am not supposed to lift anything over about 10 lbs (though I have fudged on this a bit) or ride until eight weeks have elapsed.  I am counting the days and trying to satisfy myself with walks up the greenway toward Ijams.   (And BTW, I think this greenway, along with most in Knoxville, really suck for bike riding, but that is fodder for another post.) 

It's raining violets

I can see a lot of progress in my recovery.  I started putting in some time at work, about two hours a day, three weeks ago and my hours have gradually increased; next week, I should be back to full time.  My energy level varies day to day. On good days, I am pretty much back to normal, though I have not put two good days together yet.  On the not-so-good days, my energy level is low and I tire quickly (it is quite possible that the not-so-good days have something to do with overdoing on the good days).

Bloodroot might be past its peak

May apples are unfolding themselves

I am trying to walk on a regular basis to aid my recovery and with the goal of starting to build back up to reasonable condition.  I started training before the existence of heart rate monitors and watt meters, so I know my body’s responses to exercise through experience.  Because of this, and because I am basically a Luddite, I have stuck with the level-of-effort approach to training.  However, since the valve replacement, the old cues don’t work and I can’t figure out what is going on with my body, so I bought my first heart rate monitor.

Timex heart rate monitor

I don’t expect to use it long, so I bought a cheap one, a $50 Timex ordered from my local bike shop.  The unit consists of a wrist watch that looks like it might have come out of a gumball machine for a quarter, along with the sensor that wraps around the chest.  Though it looks and feels really cheap, it is actually reasonably comfortable.  The features are limited compared to the more expensive ones, but that is all I need, and so far, it has performed admirably.  My morning walk today lasted a little more than an hour.  I kept my pulse under 140, and averaged about 110.

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Valve installation

… Continued from previous post…

The real adventure started the next day.  I woke up with a nasty migraine.  My normal migraine drugs could not be used because of possible complications, and there was not much they could do for me.  This did not turn out to be much of a problem, since they would put me under general anesthesia soon enough.

I was wheeled on my bed to a prep area.  After answering the same questions I had answered several times already, and getting hooked up to a few more hoses and “a little something in the I V to help you relax”… I don’t remember much after that.  Wife and Brother paid me a visit a little later, and they say I was talkative and apparently lucid, but I have no memory of it.  After their visit, I was wheeled into surgery. 

I started to wake up in the ICU with a breathing tube in my throat.  Brother and Wife were there, I think. 

It turned out that I was waking up at about 8:00, close to 13 hours after I had originally been put under general anesthesia.  The surgery went well, lasting from about 7:45 to 11:30.  The surgeon made the announcement to Wife and assembled family and friends.  He was excited to have been able to use a large valve (25 mm vs. the typical 21 or 23).  He also said that the old valve was in worse shape than anticipated; the opening was squeezed down to a small slit and the valve was heavily calcified (he said something about calcium deposits as big as marbles).  However, they did not save the old valve for me, so I don’t know what it really looked like; they probably just threw it to the OR dogs.

But I was still bleeding too much, so it was back into surgery.  A little direct pressure, a lot of cauterizing and about an hour later, I was back out of the operating room.  Wife had not been particularly nervous until then, but this bleeding thing got her pretty much terrified.  This process ended at about 3 PM, and they kept me under so that I would not get the bleeding started again.

We managed to get the breathing tube out in due course.  The removal was a very unpleasant moment, but after a few minutes, it felt great to get it out, and I could do a good Tom Waits imitation.  Other than that, I felt like I had been run over by a truck.

That night and the next day were spent in intensive care.  Since I had been entirely shut down and operated by machines for a while, the reset button had been pushed on most of my physiological systems and all were struggling to reestablish equilibrium, many with the assistance of drugs.  For example, I was getting hourly finger pricks to test for blood sugar, and I required some insulin for continued recovery.  The nurse told me that this was common.  If a patient were borderline diabetic, this experience might put him over the line, but most folks quickly get back to normal, as I did after a few days.

While in ICU, they started unplugging me from the various machines.  The first to go was the (surprisingly large) continuous-blood-pressure monitor in my wrist artery.  Just before I was taken to a regular room, the nurse removed my urinary catheter.  This thing was pretty useful, and I would recommend one for long car trips and meetings. 

 I stayed in the room in the cardiac observation unit until I was released.  The first night, I was helped out of the bed and sat in a chair for a while.  I walked 50 feet up the hall and back the following day, with people carrying an oxygen tank and the bottle that received the drainage from my chest.  Over the next few days, I did more walking, and they disconnected more stuff from me.  I had some further bouts with migraines, which was probably the most painful thing I experienced the whole time, though removing the chest tube was a close second.  And then there is coughing, which can be extremely painful.  They had a little trouble getting me to respond to the warfarin (couldn’t get my clotting tendency to go down, unlike a few days before when they couldn’t get me to stop bleeding) and kept me an extra night.  I was definitely ready to go home when they released me Monday.

I think I got pretty good care, all in all.  Some of the nurses were great; only a few seemed to just be putting in their time.  All of them seemed spread too thin.  The food was about what you would expect.

I am writing this two weeks after surgery.  Progress toward recovery continues, but not as quickly as it did at first, or so it seems.  My back hurts, I am getting two migraines a day, I still tire very quickly, and my mood is a bit down.  But I am also doing more things around the house.  I read an entire New Yorker today.  If it gets a little warmer, I can go outside for a walk tomorrow.  Bottom line is that the new valve is not yet showing any improvement over the old one.  I will give it a while.

My love goes out to all the family, friends, and neighbors who have given us support and Food over the last couple of weeks.  You all made this a whole lot easier for me and for Wife.

Footnote: I heard a few comments over my days in the hospital (especially while checking in) about identity theft, and every time I changed rooms, they asked my name and DOB.  This seemed a little paranoid to me, but it turns out that is something of big deal, as discussed on NPR this morning.

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New Valve

I pulled the trigger on the valve purchase.  The winner is the Carbometrics Top Hat, a fine piece of Italian equipment, made of titanium and carbon (not carbon fiber, but pyolitic carbon , which I gather is the same material as carbon fiber but in a sheet form).  The product brochure really makes you want one, even if your existing valve works just fine (Supra-annular positioning for the  Biggest Valve Possible! 40% greater flow!!!).

BTW, this is not something for which I would recommend DYI installation.  Splitting your own sternum and slicing open your own heart is awkward at best.  You might make a try if  you have a friend who dresses his own deer and has a good bone saw, a wife who is good with a needle and thread, and an uncle who makes some whoop-ass moonshine.  You might even be able to rig up a heart and lung machine using an air compressor and that old peristaltic pump in your junk box.  However, this is a much more complex process than most of us are ready to tackle.

My installation process began on Tuesday, 2/16 with a little recon in the form of heart cathaterization.  The cardiologist inserted a probe in the artery in my groin and ran it up to my heart.  This was done under a local anasthetic, so I could observe some of the activitiy.  I could not move my head much, and I really did not want to see them feeding objects into my artery, so I did not get a complete picture of  what was happening.  It appeared that the crew took x-ray photos of the probe in place and also used the probe to inject dye visible to x-rays and take more phtos of that.  I could see some of this on the computer screen, but I could not interpret the shadowy images.

The cardiologist’s conclusion was that my arteries were clear and in good shape, so there would be no need for any additional procedures when they had me open.  However, the cardiologist did not sound totally convinced that the valve was bad enough to replace.

This process left me feeling fine, but I was told not to move my right leg or lift my head until 8:00 that night, about 6 hours after the heart cath procedure, because those motions could cause bleeding from the insertion site.  This made it a bit awkward when it came time to eat dinner.

When I could move again, I was carted (in a wheel chair) down to x-ray for  some more shots of my chest.  Over the course of the day, I must have absorbed my limit of x-radiation for the next several years. 

After that, the groomers came in and I was treated to a neck-to-ankle hair clipping, except for my back and the part of my pubic hair left from the heart cath prep.  I am moderately hairy, so this took a lot of effort on the part of the groomers.  The clipping was followed by a shower, and what was possibly the blandest snack (saltless soup and saltless saltine crackers) of my life.  Then it was time to go sleep so that I could get up fresh and rested for my 6 AM surgery prep.

Continued…

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Valve shopping

I am in the market for a new aortic valve — the old one is shot.  I would like to get something vintage, maybe lugged steel.  But it turns out that none of the well-known classic marques like Huret or Campagnolo — even Shimano –ever made such things, at least I can’t find any in the catalogs or on ebay.

So here are my choices.  I think the ball-and-cage look is pretty dorky.  The single flap might work, and it does have some vintage charm.  Pig valves have a certain appeal, but I hear they might result in weight gain.  The two-flap venetian-blind design seems to be the current thing.

With no other viable choices,  it looks like I might have to violate my old-school sensibilities and go all carbon and titanium. This one from ATS Medical looks pretty good — nice clean design with no ugly graphics.  I wonder if I can choose the color.   A nice sage green sounds about right.

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Handlebar bags and the Velo Orange Campagne Front Bag

Handlebar bags don’t get much respect here in the U.S., presumably because most people want to look like racers, but I like using them.  For general non-utility riding, they are the most convenient place to put food and extra water, extra clothes (leg warmers; jacket), tools, and other miscellaneous stuff you are likely to need during your ride.   You can put all your gear in them on short rides or day rides, or the stuff you need easy access to on a multi-day tour.  And as a bonus, most bags have a map window mounted on top to make navigation easier.

Of course, your jersey pockets can hold some of this kind of stuff, but the capacity is limited, things get sweaty, your pockets get stretched and torn, and you squish your banana when you get off the bike and sit in a chair or car seat.  If you are limited to jersey pockets, you will probably leave some potentially important things at home, or skip riding altogether, if the weather is changeable.  If you depend on your jersey for for carrying stuff, you have to wear a jersey in order to ride anywhere, which limits your riding options.  If you want to look like a pro racer, remember that they have follow cars and domestiques to carry the gear that keeps them from the bonk and hypothermia.

A Cannondale handlebar bag served my needs, off and on, for close to three decades.  It is close to total failure with a main seam  pulling apart, the color  faded, and the leather trim dry and cracked.  The map case is long gone.

Three years or so ago, I bought an Arkel to replace the Cannondale.  This is a great bag, and the only problem I had with it was that it was a little difficult to remove if you wanted to take it with you when you got off the bike.

Even before I bought the Arkel, the traditional French-style front bag has that sits on a front rack has intrigued me.  This was partly because I found the old-school style and materials (canvas and leather) appealing, and partly because a front rack is the best place I have found to put a headlight if you have a handlebar bag, so I already had a support for the canvas bag on my touring bike.  There as a technical reason, too: sitting on a rack, the French bag sits lower and closer to the steering axis than a bag mounted on the handlebars.  This should provide a benefit in handling. 

The main option for this style of bags are the ones made by Gilles Berthoud in France.  Due to the cost and the mounting complexities I could never pull the trigger on the purchase of one of these.  A second option became available in the Japanese-made Ostrich bag from Velo Orange.  The price was a little more reasonable (approximately half the price of the French bags), but I could not get past the front-opening flap on the top, which seemed much less easy to use and likely to blow open when the bike is in motion if not properly sealed up.   A third possibility was the  Acorn, but supplies were limited and they were not even keeping a waiting list.  One other option I did not consider very seriously was one of the various trunkbags sold by Rivendell.  These bags have most of the function of the French-style bags and are reasonably priced, but are not designed for ease of access and do not have map cases.

This spring, Velo Orange started selling a Berthoud-copy bag for less than $100, called the Campagne bag.  Soon after the bag came out, they introduced their own stainless steel decaleurs for mounting the bags.  This bag looked like the best possibility yet.

VO wholesales the items made for them, so I got my local bike shop (Tennessee Valley Bikes) to order the bag for me.  It arrived quickly, and the initial impression of quality was good.   There may be some karmic penalty for buying the cheaper imitation, but I am not sure that the Chinese people who probably made it deserve the work any less than the French. 

I initially attempted to mount it without the decaleur, and found the stability of the bag unsatisfactory.  In addition, the chords that went to the handlebars were interfered with my hands. 

So I ordered decaleurs for two bikes.  After some fussing, I got everything mounted on the touring bike (the green bike had to wait for another rack, rack braze-ons, and a paint job [see previous post]).

The result was worth the trouble.  The load was carried in a way that interferes noticeably less with handling (not that the previous bag was problem, but it was noticeable).  The handlebars feel more spacious because there are no mounting hardware on the bars, nor is the bag itself close to my knuckles.  The contents of the Campagne are reasonably accessible while rolling and even more accessible when stopped, even while still straddling the bike.
planview

I do have some quibbles.  For one thing, the bag could be a little narrower and an little longer.  That would allow it to fit between handlebars and between bar-end shifter cables a little better and make the aspect ratio of the map window a little more useful, while maintaining the same volume and still allowing a good fit on a Nitto rack (I don’t know about VO racks).

VO supplies nice stainless decaleur hardware that will last forever.  They failed to give the same attention to the steel hardware (buckles and loops) on the bag.  The bag has been in a light rain once, and is stored in my unheated garage.  The hardware is already rusting.

Rusty buckle

Rusty buckle

The bag is a little floppy laterally.  This would be fixed easily by connecting the side stiffeners to the decaleur mount.

Lateral flop

Lateral flop

And speaking of the decaleur mount: it is well made and well aligned, and the bag is very easy to remove.  But there is no resistance to bouncing out of the mount.  On my first ride with the bag, it bounced free on minor bumps at least 4 times in about 45 miles.  An anchoring mechanism would be nice.  I added a small bungee as a work-around solution.

Small bungee to prevent bouncing out of the decaleur

Small bungee to prevent bouncy out of the decaleur

The decaleur has no vertical adjustment to compensate for different frame sizes/head tube lengths.    The Berthoud bags come in different sizes, with taller bags for taller frames.  I don’t like that solution much, because I bought the bag partially because it was a good size.  I ended up bending the part of the decaleur mount that is connected to the bike; in the case of my touring bike, the bend is rather severe.

Mounting the decaleur to the bag required drilling or punching holes for the screws.  It seems to me that the bag should come with grommeted holes for this purpose. 

The closure for the top flap is an elastic cord on the flap and a hook on the body of the bag, similar to the Berthoud.  This works badly, at least on my setup, because it is difficult to work the cord around the vertical part of the rack.  In pictures of the Berthoud, it looks like the rack fits tightly up against the bag and perhaps the tubing diameter is smaller on their rack, and maybe this is the case if you use a VO rack.  I can’t think of an easy way for an easy universal fix for this, but it works adequately to just wrap the cord around the decaleur mount. 

Cord and hook for flap closure

Cord and hook for flap closure

Criticisms aside, I love the bag and would recommend it to others, but a few modifications would make it perfect.

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