Monday, December 9, 2013

Tires

A sew-up (tubular) tire dissected. At the top is the rim tape, which for a sew-up is first glued to the tire and then to the rim. This tire has been used (and punctured) and you can see the staining from the aluminum rim on the tape. In the middle is the black (butyl) inner tube. I actually did not know if this particular tire had a latex or a butyl tube until I opened it up to repair it just now. Unlike a clincher tire, where the tire only covers three sides of the tube and has a wire or kevlar bead to hold it to the edge of the rim, in a sew-up, the tube is completely surrounded by the tire which is held together by the stitches on either side of the tube and then glued to the rim. I had to cut the stitches to get at the tube to repair it, and will have to re-stitch the tire when I am done.

My second 10 speed (road bike) was a Peugeot PX10, and like all high end road bikes of the 1960's, had "sew-up" (tubular) tires. Most sew-ups contained inner tubes made from latex, which can be recognized by its light tan color, as opposed to the black color of the more common butyl rubber tubes. This was done because latex is thinner and softer than butyl rubber and thus has lower rolling resistance; it makes for a faster tire1. The problem is, latex doesn't hold air as well as butyl rubber and latex tubes need to be re-inflated every day. Sew-ups were also expensive. As a solution to both of these problems, Clement, the largest vendor of sew-ups, marketed the Clement 50, a relatively inexpensive, rather heavy sew-up tire which had butyl tubes. Because of the butyl tubes, you could go up to a week without pumping up your tires. Thus, besides saving money, Clement 50s had an advantage as an every day training tire in that you could just jump on your bike and ride without the delay and hassle of tire inflation. This seems like a small thing, but small things like that often make a disproportionate difference and what many of us found is that not having to inflate tires often made the difference between going for a ride or putting it off until tomorrow.

When I purchased my first modern bike, my Surly Crosscheck, one goal was a fuss-free ride to facilitate "just jumping on the bike" but life is more complicated than that. One can be motivated by convenience (Clement 50 tires with butyl tubes) but also by performance (ultralight, ultrafast, silk sew-ups.) As practical as it was, I found my Surly a bit drab. It was not particularly heavier and no slower than my much less practical Bianchi Specialissima, but it was way less exciting. One thing that particularly bothered me were the tires. The Crosscheck is a cyclocross bike, and as such, comes with wide (32 mm) knobby tires, which to my retrogrouch eyes looked clunky. (Also, I found that the buzz the knobs made on pavement annoying.) So, the first modification I made to my Surly was to replace the tires it came with with skinnier (28 mm) tires with smoother tread. I didn't think too much about which tires to buy so long as they were skinny and slick and just got whatever the guy in my local bike shop (LBS) told me to buy. I no longer have any memory of what brand of tires these were.

By the time I rode my first 200K brevet two years later, those tires needed replacing. This was discovered when I took my Surly into my LBS for a pre-ride tuneup so again, they just put on whatever they had around in 28 mm width, which happened to be Specialized Armadillo tires. I rode these for my first brevet and for all the riding for the next year, until my second brevet a year later, at which point I wanted to try some 32mm Grand Bois Extra Léger tires. I had been reading Jan Heine's blog who argues that the most important upgrade you can do on a bicycle is the tires, and promotes his own brand of of tires (the Grand Bois) as the best. In fact, I loved these tires and successfully rode my second brevet on them, though I was not able to confirm any performance improvement of them over the Armadillos. What was somewhat ironic about this choice is that it was a retreat to a wider tire that I was so eager to abandon a few years earlier.

Specialized Armadillo

Grand Bois Extra Léger

As much as I loved riding the Grand Bois tires, they are quite expensive and appear to be fragile; their low rolling resistance comes from the use of a very thin sidewall and tread. Also, I read in a number of reviews that these tires should be aged for a year before use. Thus, I used these tires for a ride or two before the brevet (to make sure they worked), for the brevet, and then a few days afterwards replaced them with the old Armadillos with the plan of putting the Grand Bois back on for the next brevet both to save them for events and to give them a chance to age.

About a month ago, the Armadillos wore out. Although they were fine tires, I had felt a bit uncomfortable that I had no say in selecting them, they were the choice of my LBS. So this time around, I wanted to actively select a tire. While reading posts from long distance touring cyclists, I saw repeated recommendations for Schwalbe Marathon tires, so I ordered a set in the 28 mm width from Amazon with the idea that if these were good enough for around the world cycling, they should be good enough for fuss-free cycling around town.

I don't know how I will feel about my Schwalbe Marathons in the long run, perhaps I will never get another flat and that advantage will trump everything. However, if I had it to do over again today, I would not order these tires2. In the first place, they were the most difficult tires to mount of any I can remember. Reviewers do warn of this, but I did not appreciate the extent of the problem. Apparently, Swalbe is well aware of the issue and makes a special fluid and tire irons to mitigate it. I did get the tires mounted without the fluid and with my standard tire irons and the effort involved was significant but not a show stopper. However, I worry about what will happen if I do get a flat and have to remove these tires on the road.

A second, perhaps more serious problem I have with these tires is how they handle. An advertised feature of these tires is a strip of a blue material between the tread and the casing put there to increase puncture resistance. This also increases the weight of the tires which this is not an issue for me given the weight of the rest of my bicycle and, much more importantly, my body. The rolling resistance of the tires seems fine to me as well. The issue I have is that sometimes, when cornering, there is an uncertain feeling, like you are about to loose traction. (I am not particularly aggressive while cornering.) I never have lost traction and it is my sense that this is an illusion rather than a true limitation of the tires. That said, I am suspicious that this feeling is caused by the blue strip under the tread. I suspect that this strip makes these tires stiffer and less responsive to the road, creating the disconcerting feeling, but that is just a conjecture. To put this all into perspective, I had put the original knobby tires back on my bike for a few days between the time I had noticed that the Armadillos were worn out and the Marathons arrived, and they feel dramatically worse to me than either of these tires, so the Marathons don't so much feel bad as they feel not as good as the Armadillos.

Tire Width


27x1¼" (32 mm wide) tire on the left, 700C 28 mm wide tire on the right. I claim the 28 mm tire is noticeably skinnier (as it should be.)

The same 27x1¼" (32 mm wide) tire on the left, but a 700C 32 mm wide tire on the right. I claim these are relatively similar in width.

Fat tires are in these days, and have been for a while. My wife's Surly, purchased in 2010, has a decal on the rear stays reading "Fatties Fit Fine", which offended her until I explained it referred to the tires. I have read the studies saying that fatter tires at lower pressure can have both a more comfortable ride but also lower rolling resistance than skinnier tires. That said, my sensibilities were formed in the 1960s when skinny tires were in; we believed that the skinnier the tire, the higher the tire pressure, the faster the ride, so when I see a fat tire today, my aged brain thinks "slow and clunky".

Back in the 1960s, there were four general sizes of tires on our radar. This was a bit complicated by the fact that Schwinn bikes used different sized tires as everyone else, but the grouping works nonetheless.

Regular one speed cruiser bikes used fat tires that were labelled 26x1¾" (Schwinn) or 26x1.75"(everyone else.) I had a bike with this size tire that I used for my paper route. These correspond to ISO 54-571 and 47-559, respectively, which means they were 54 and 47 mm wide. For perspective, modern 650B tires, extra-fat tires especially designed for dirt road randonneuring, are rarely more than 42 mm wide. On the other hand, those old 26x1.75" tires fit onto the same rim as the tires used on modern 26" mountain bikes. In that context, the 1.75" width is near the higher end of for a width of these tires, but would be no where near the widest.

On the right is one of my new Schwalbe Marathon tires (700Cx28mm). On the left is a 700Cx23mm clincher I have on my Bianchi Specialissima. The tire on the left is much skinnier (and thus to my eye, more attractive) than the one on the right.
Three speeds, sometimes called "racing bikes" back in the 1960s, used a distinctly skinnier tire. The local bike shops would discourage these for children, claiming they were too delicate. Both Schwinn and other bikes designated these tires as 26x1⅜", but the tires were different sizes and non-interchangeable, ISO 37-597 and ISO 37-590 respectively. However, both were 37 mm wide, a very wide tire for a modern road bike but a very typical tire width for a 650B tire used for dirt road randonneuring.


This time the comparison is to the same Schwalbe Marathon tire but now to a sew-up on my Bianchi Specialissima. To my eye, the sew-up is even skinnier than the 700Cx23mm shown above.

Cheap ten speeds had tires marked 27x1¼" which are ISO 32-630 and 32mm wide. Expensive ten speeds had sew-up tires which varied somewhat in width but typically were 23 mm wide and correspond to a 23-622 ISO size. We knew that the sew-ups were skinner and could be pumped up to higher pressures (over 100 PSI vs 70 PSI for the 27" tires) but thought of both of these as skinny. When my wife and I first started riding together in the early 1970s, she had a three speed, felt the tires were fat and slow, and upgraded to a cheap ten speed, which she and I felt had skinny tires. Note that these 27x1¼" tires are 32 mm wide, the width of the fat tires that came on my Surly, to which I objected. When I was installing my 32mm Grand Bois, I knew they were fatter and wanted to compare them to what I had been riding. I noted this was nominally the same width as 27x1¼" tires which I considered "skinny", and thought that had to be a mistake, but when I put them side by side, I found that the widths are the same. To this day I have no idea why a 27x1¼" tire looks fairly skinny to me, but that a 32 mm wide 700C tire looks fairly fat when both are 32 mm wide, and that the difference between a 26x1⅜" tire and a 27x1¼" tire (37 and 32 mm, a 5 mm difference) seems big, whereas the difference between a 27x1¼" tire and a sew-up (32 and 23 mm, a 9 mm difference) seems not so big. Note that this discussion is esthetic. The only tires whose width I selected entirely rationally are the Grand Bois.


Footnotes


1. It is possible to purchase latex tubes for modern, clincher tires.

2. For those who need a reason to use their LBS, this is one. The tire selected by my LBS is the one which, in retrospect, I would now purchase; an advantage of using one's LBS is that you get the benefit of their experience. However, the fun of working on my bike is an important part of cycling for me and well worth the problems that result from my relative inexperience. Someone who just wants a bike to ride may well come to a different conclusion.

2 comments:

  1. Catching up on your blog.
    As an older rider (48), I'm interested in your training experience.

    But, those look like Marathon +'s, not Marathons. The pluses are super armored, much more rolling resistance and weight then the Marathons.

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    1. Right you are, sir. Obviously, I did not appreciate the distinction when I ordered them. Some would correctly see this as a reason to use their LBS, in that the LBS would have the experience to know what the choices are and what they mean. I see it as a learning opportunity :-)

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