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
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
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.”
“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.”
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.