Jim’s Tech Talk
By Jim Langley
The question in the title was asked by RBR regular contributor “Fixie Guy.” If you comment on articles and read them you’ve surely benefited from his tips and insights. The question he asked this time interested me but I didn’t have a very good answer for him. So he went to a higher authority.
Read on to follow the entire thread, which includes his questions and comments, my replies and one from the tire company Vittoria, too. Then please comment with your take on directional tires.
Fixie Guy first wrote
Hi Jim,
I hope you are doing well and are enjoying your new gravel bike.I have flip-flop hubs on some of my fixed gear bikes but rarely ride with gears on both sides. I was thinking about putting a second, slightly lower fixed cog on the unused side of one bike. [Editor’s note: a flip-flop hub means that the rear wheel can be flipped around in the frame to change gearing.]
However, I remembered that the tires I am using, Vittoria Zaffiro Pro and Continental Grand Prix 5000, have specified rotational direction. That means if during a ride I want to flip the wheel around I will either ride with the tires rotating opposite the specified direction or I will have to remove the tire and reinstall it so that it rotates as specified. The latter seems like a pain in the neck.
Does riding a road tire in the “wrong direction of rotation” cause any harm to the tire or cause any risk to the rider?
I’m assuming that for mountain bikes, specified rotational direction will be oriented toward better steering on the front and better traction on the rear. I don’t see that as an issue on road bikes.”
My First Reply
I was thinking of how to answer your question with something helpful and all I can come up with is that I’ve never been able to tell any difference in performance from directional tires. With such a tiny tire contact patch it’s hard to see how any directional tread could make that much difference on road bikes ridden on pavement.
Fixie Guy’s Response
“Thanks Jim,
I’ll take that as meaning that using them in the wrong direction would not, to your knowledge, cause any harm to the tire nor cause any risk to the rider.
Like many seemingly purposeless things in life, it leaves me boggled by the mystery of why tire manufacturers would bother to bear the additional expense to put that directional arrow on the tire if it has no purpose?”
My Second Reply
Actually I could have added one more “data point,” Fixie, which is that Jobst Brandt who many considered a brilliant engineer (backed up by some impressive automotive and cycling inventions), did lots of tire testing in coming up with Avocet’s line of road tires (photo). He determined that the best all round road tread was completely bald, no tread or features at all. Here’s Jobst’s talking about this on Sheldon Brown’s website: https://www.sheldonbrown.com/brandt/slicks.html.
Maybe someday I’ll get to speak with a bicycle tire engineer and ask them. I’m interested in what they would say too.
But yes, I don’t think it will harm the tire or put you at risk. Hmm, maybe if you reverse the tread the tread will wear out faster in the wrong direction. So maybe it will harm the tire in a way?
Fixie Guy’s Response
“I’m going to try to contact Continental and Vittoria’s customer service folks to try to get an answer. Now I’m just very curious. Here’s the question I’m sending to Vittoria:
Your Zaffiro Pro tires have an arrow describing proper rotation direction. Why is that? What harm would occur if mounted and ridden in the wrong direction? Thank you.
And here’s Fixie Guy’s Final Response with Vittoria’s Reply
“Here’s the response from Vittoria, Jim. It seems there is no meaningful purpose to the directional arrow. I’ve not heard back from Continental.”
Vittoria’s Response
“There is no harm in running our Zaffiro tire the opposite way. They do have some rain groves to shed water. This would have some effect in wet environments but in dry conditions it does not matter.”
Your Turn
So what do you think readers? Have you ever run directional tires the wrong way by mistake or on purpose and noticed a difference. Do you have any more insights for Fixie Guy?
Jim Langley is RBR’s Technical Editor. A pro mechanic & cycling writer for more than 40 years, he’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Tune in to Jim’s popular YouTube channel for wheel building & bike repair how-to’s. Jim’s also known for his cycling streak that ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
I agree with Vittoria. I have some Michelin Power Road TLR tires that are directional because of the siping to channel water away.. When mounted in the correct orientation, water from the near center will be moved to outside of the tire..
From MTB’s early days we would run tires with the directional arrow backwards on the front, since the front and rear have opposite functions traction wise. (ie front for braking, rear for drive) specifically remember this with the Panaracer Smoke (prior to the front only dart being available). Honestly didn’t notice a difference. I usually run road tires with the directional arrows in the right direction, out of habit/OCD. 🙂
The running joke here on internet bike forums is that tire manufacturers put directional arrows on their tires so that they won’t get so many questions from owners about which direction to mount the tires. Even the response from Vittoria is a bit bogus as bicycle tires don’t ever hydroplane and “shed[ing] water.” is not a real thing even in downpour conditions.
It’s a geek detector. At stops, geeks, who have better things to do than simply enjoy riding, can come up to you and advise you that you have the tires rotating in the wrong direction. (This takes a far more advanced geek than those that simply look to see if the QR skewers are on the non-drive train side…) Don’t worry – in about 40 years or so you will learn to ignore these folks!
At an Interbike expo long ago I asked the question to a guy manning the Continental booth.
I told him I’d only recently noticed the arrows and had reinstalled some tires to get it right on several bikes.
“The direction doesn’t make any difference,” he said.
Then how come the arrows?
“I dunno.”
I have run several tire brands in the “correct” and “non-correct” rotational direction. In non-race situations, I have observed no significant differences on road bikes (dry conditions).
I have always been under the impression (not fact/data based) that running tires in the “correct” direction was best for speed/smoothness and in the “non-correct” for more grip. And that this is more pronounced on dirt (gravel or mountain bikes).
I had a vague recollection that Schwalbe had done some research on this, and come to the conclusion that it doesn’t matter. But here is what I found on their website:
In the case of a road tire the rolling direction is mainly important for aesthetic considerations. Tires marked with arrows simply look more dynamic.
Off road, the rolling direction is far more important, as the tread ensures optimumconnection between the tire and the ground. The rear wheel transmits the driving force and the front wheel transmits the braking and steering forces. Driving and braking forces operate in different directions. That is why certain tires are fitted in opposite rotating directions when used as front and rear tires.
Dang, how many times have I put on a new tire only to realize it was mounted rolling the wrong direction and took it off and remounted it the “right way”
On farm tractors it matters!
Guess those arrows are to prevent questions “Which direction I should mount this tire?”.
Number of people, asking “Why this direction” is supposed to be substantially lower.
On the Conti road tires, the tread pattern seems to point in a specific direction. My anecdotal theory is that this was designed for better traction on wet roads. Hence, the direction arrows on the tires. My other hair-brained theory is that bald tires (baloney skins) would have poor traction on sharp turns in the rain.
Hi Jim,
Interesting topic! As you know, my passions include bicycles and motorcycles. With street oriented motorcycle tires, if you mount them in the wrong direction, the tires will run hotter. Because bicycles are lighter, slower, and have a tiny contact patch, this difference may not be detectable.
Thanks for sharing this Harold, very interesting.
Jim
No response from Continental? I’m not surprised. I’ve been trying to get info on tires sizes from them, with no success. I’ve talked with a number of vendors… mail order shops, bike shops, QBP, and even the USA importer for Continental… and none of them can get any response from Continental. Nice tires, but horrible customer service.
From Schwalbe; Road tire tread is just cosmetic to increase sales. Smooth tires sell less well.
Instead of asking the tire engineers it might be more useful to as the tire company lawyers. Bet there is something there to protect them in court.
I’ve been riding for over 40 years, and the idea that the tire contact patch is so small it won’t matter is the correct thought.I
It’s difficult to find a tire without some sort of pattern on it, those patterns are all about marketing and nothing else, they’re designed to make people think they’re getting something better with that tire, after all, car tires have patterns so why not a bicycle tire? it’s just marketing hype.
I remember many years ago having a conversation with Dr Bose of the Bose speaker company at his office. When I walked in I notice he had a pair of Bose 901’s hooked up, but he had them turned around facing the wrong way, in other words, the speakers were aimed at the wall and the bass port was aimed out into the room which is now how they were demonstrated, sold, or the instructions said to do, when I asked him about it why they were facing the wrong way, he laughed, said these simple words, “Son, it’s all about marketing and how the public perceives things as being normal.”
So bicycle tires with patterns are normal for people who own cars to think about what a tire should look like.
The word now in the sentence: aimed out into the room which is now how they…, is supposed to be NOT, typing error.
The tread rubber. is wrapped around the casing with a tapered “skived?” ends that overlap. the direction the overlap points should be to the rear so braking forces can”t peel the tread rubber off the casing.
On a vulcanized tread, that doesn’t matter, as the tread is fused together in the mold. Handmade tires like tubulars and “open tubulars” use treads that are molded in a loop, so there is no seam.
Thanks very much everyone for the great comments!
Jim
It’s important on the front tire because you can see that one and it looks dumb if mounted backwards. It doesn’t matter on the rear because if you’re looking at your rear tire, something has already gone awry.
Thanks everyone for your comments. First, I’ve always thought that on road tires, direction made no difference but tended “to follow directions” presumably because of my strict upbringing. Second, back in the day, tire manufacturers put their label on only one side of the tire. Bike style evolved that the tire label should be on the right side and centered over the valve stem. Then the sales and marketing folks realized that they could make huge labels advertising their brand and put them on both sides so we purchasers could be rolling advertisements for them. Of course, then we did not know our right from our left. As some commenters have suggested, that may have led to many people asking which was which and that led to directional arrows.