Tech FAQ: Cold tires and brakes

By Lennard Zinn
Published Tuesday, 25 November 2014

Andrew Isaacs, a reader in Winnipeg, Manitoba, has some advice for riding in sub-zero temperatures. Photo: Andrew Isaacs

Andrew Isaacs, a reader in Winnipeg, Manitoba, has some advice for riding in sub-zero temperatures. Photo: Andrew Isaacs

Dear Lennard,
Minnesota is getting blasted by its first storm of the season, which has me wondering: Are narrower or wider studded tires better for riding on icy roads? Wider mountain bike tires have a wider contact patch with perhaps more studs in play, but narrower tires have a higher pressure contact patch and maybe more traction, right?

Which size tire do you think works best?
— Charlie 

Dear Charlie,
I am deferring to a buddy of mine who rides studs a lot. Since I work out of my house and don’t need to commute, I can pick my cold-weather riding. I love riding in snow, but I avoid ice and don’t ride with studs. But my friend Mike Prendergast, who did this awesome film about riding all winter long, is an expert on riding studded tires. Mike has this to say:

Winter cyclists encounter a mix of fresh snow, compacted snow, and ice. And some will face rutted snow or ice on roads and trails.

Studded bicycle tires are fairly wide with the narrowest being around 35mm. In my winter riding experience, the width of the tire is more critical for riding in snow while the number and placement of studs is important for ice. For ice without ruts, studded tires of any width have superior traction.

If you are riding on plowed roads and paths, a tire with around 100-120 carbide studs will be a good choice. If you ride on dirt roads or paths that may or may not get plowed, then a tire with around 240 carbide studs will be needed to handle ruts. Ruts will form after trail- and road-user tracks refreeze.

You will only need wider tires to stay on top of deep snow. As long as the snow depth is not more than a few inches, even a fairly narrow studded tire will drive down and get good traction.
— Mike Prendergast
ChainRing Films

Enjoy riding on the ice, Charlie!
— Lennard

Dear Lennard,
I have begun using tubeless tires on my mountain bike in the past year.

With the colder weather, I am wondering what happens to the tire sealant in the cold. Do tubeless tires work just as well when the temperatures get below freezing? Can I expect lumps of hard stuff rattling around in my tires if I hit the trails when the thermometer is in the 20s?
— Bruce

Dear Bruce,
Tubeless sealant is water-based and will freeze. If your bike overnights in a warm house, and the trails start from your house, performance will be okay for awhile. And in that case, any liquid sealant will have been distributed around throughout the tire before it freezes, so you won’t have chunks rattling around.

But if you drive to the trailhead or store your bike in the cold, you could get frozen chunks rattling around in them, because liquid sealant will have pooled up at the bottom and then frozen. (Orange Seal makes a tire sealant it claims is good in temperatures as cold as “negative teens” -Ed.)

Either way, the combination of frozen sealant, reduced tire pressure, and the tire being stiffer due to the cold makes the sealing of your tires more tenuous and negatively affects its ability to absorb side impacts without dislodging the bead.

Due to reduced speeds in the cold, stiffer, cold tires, and fewer thorns, dangers of pinch flats and punctures are reduced anyway, so there’s less of a downside to using inner tubes.
— Lennard

Dear Lennard,
After watching the near implosion of disc brakes in cyclocross from the seemingly instant and complete wear at Nationals not long ago I was nervous about discs in cyclocross.

I now have a disc bike and have purchased, but not installed, some sintered pads for wet conditions.

It isn’t yet wet and I have some questions. Should I install them now or wait for the conditions to warrant the change?

I followed everyone’s advice and “broke in” my original discs and pads with a few dozen hard stops from full speed. Do I repeat this with new pads or just when I change the discs?
— Davo

Dear Davo,
Yes, in the case of thin mud, sintered pads are better. If you do anticipate thin mud for an upcoming race, you might as well change to sintered pads ahead of time. It’s much less fun to change pads in a rush outdoors in cold weather before a race, and you ought to get used to the feel of braking with them in dry conditions, because many times it will turn out dry when you prepare for mud anyway. You don’t need to replace the rotors; you can just break in the sintered pads on the same rotors (and yes, follow the same break-in procedure).

That said, having a set of wheels with mud tires that have solid rotors on them could eliminate pre-race stress. Solid rotors will make way more difference than the sintered vs. organic pads would have anyway. And if you can also switch to the sintered pads in advance, you will have the ultimate setup for thin mud. If the mud turns thick, you won’t need the solid rotors or sintered pads, but there is little downside to having them.
— Lennard

Dear Lennard,
I recently bought a set of black brake pads from eBay for my carbon clincher wheels. Since I’ve installed them, they been leaving white powdery residue on the brake tracks. I’m able to clean them up pretty easily by wiping it off after my ride. I’ve logged about 80 miles on these pads. These are my third set since purchasing the wheels. I don’t recall the first two sets leaving any powdery residue.

If I was mistakenly sold brake pads for alloy wheels, what symptoms will I encounter? Are there any noticeable differences between the pads, such as thickness or shape? The new pads don’t make any irregular noise in comparison to the previous pads. I’m just little a concerned.
— Dennis

Dear Dennis,
On a hot day with heavy braking on a mountain descent, alloy-rim pads on a carbon rim will tend to melt.

In cooler conditions, they will tend to erode like an eraser rubbed on a piece of paper. It will be powdery. I don’t know about white, though. I would call it more gray from a black pad, but against a black carbon rim, maybe it looks white.
— Lennard

Dear Lennard,
I’m from Winnipeg, and I commute year round. My cutoff is about -25 Celsius (-13F) these days, but I have gone lower in the past, down to -40 (-40F. This is the crossover point, where Celsius and Fahrenheit temperature is equal; I can’t imagine riding at that temperature! -LZ).

A few more things that seem to really slow me down in the cold:

  1. Squishy Nokian winter rubber is slow.
  2. The grease in my hubs and bottom bracket turns into sludge in the cold, as well as the oil on my chain. Sometimes it feels like the wheels barely turn.
  3. Riding on snow is like riding on sand. I try to ride on ice or hardpack as much as possible, but it obviously makes a huge difference. As soon as you hit the snow, you also pick up rotating mass in your wheels. (See post-wipeout pic above).
  4. The clothing surface area is probably at least double, and as you point out this is really critical. The wind also contains a lot more power due to increased density, and any kind of headwind is killer.
  5. I tend to disagree with the “your body slows down” arguments, since regardless of temperature, I’m normally toasty warm a few minutes into the ride. A light fleece and a good shell over your whole body is enough, as long as you take care of covering your face and eyes. Wind chill is not as big a deal as it seems.

Andrew


TakeAways

I met Lennard Zinn several years ago when he was visiting Chicago on a book tour. He gave a presentation/lecture at the Oak Brook REI store.