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Apparel & Accessories

Technical FAQ: Skin sensitivity to synthetic materials

Our technical expert discusses rashes and adverse reactions to materials used for cycling apparel.

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Have a question for Lennard? Please email him at to be included in Technical FAQ.

Dear Lennard,
I was impressed with your responses to SPF protection questions, very important for us cyclists. What about hypoallergenic cycling clothing? After decades of avid bicycle racing and training, I have developed a sensitivity to many synthetic fabrics. Not the chamois, it’s the stretchy stuff. Do any of the top cycling apparel makers specialize in gear for this issue? I do wear wool whenever possible but have yet to find any high-quality wool/hypoallergenic shorts suitable for long days in the saddle, indoor and outdoor. Perhaps your contacts in the industry know more than Google on this topic.

I have ridden 5,000 to 10,000 miles each year since about 1990. In the last 4 years, with the advent of Zwift and smart trainers, I have probably done half of those miles indoors. Some weeks in the winter will be 7 to 15 hours, and some rides as long as 4 hours without a stop. So, my bibs and butt see a lot of action. Each year our racing club buys new kits, and I buy two new pairs every year. Made by Voler, and they do a great job for us. I will also buy a pair of Rapha shorts every couple of years, just to mix it up a little. There are about eight pairs of bibs in my rotation, and they are washed thoroughly after every ride. Every ride starts with clean shorts. I never wear my new kit indoors. I save my old ones for the indoor rides. They all hold up very well, and I am impressed by the quality of the bibs I own. My skin sensitivity issues are the same whether indoors or out. The butt rash went away and stayed away for over a year since I started using Vaseline instead of Chamois Butt’r. No way can I be sure if that is the reason but it’s working for me now.

My biggest concern is a reaction to synthetic stretchy fabrics. It is not debilitating, but it sure is a nuisance. I get a rash around my chest from the HR strap. I switched to an arm strap, and I get a rash from that also. All my street clothes are natural fabrics, either cotton or wool. The only synthetic fabric I wear is on the bike. I almost always wear a lightweight wool undershirt when riding, except indoors, when I wear a cotton t-shirt. I still get itchy around my waist and midsection, so I am assuming it is caused by my bibs. I have searched for high-quality cycling shorts/bibs in wool with no luck. I have read your stuff for years, and it is always useful. Your thorough discussion on SPF and crash protective fabrics gave me hope that your connections in the industry may have an idea for me. (Don’t worry! I will continue reading your material regardless of any skin problems.)

What should go between you and your chamois? Photo: Brad Kaminski |

P.S. I did read your Technical FAQ on chamois allergies. I also had that same issue and have resolved it. As a racer, I probably have a dozen pairs of bib shorts. I also spend many hours indoors on Zwift (Level 50+ and 17,000 miles over the last 3 or 4 years). My butt rash was unbearable. The skin doc said to stop using my chamois cream and try Vaseline instead. What! Vaseline? No way! Well, it worked, and I have been using Vaseline for a couple of years with no problems. Once applied to warm skin, it loosens up and provides all the lube needed. Have you read the ingredients list on all those chamois creams? If I can’t pronounce it, I don’t want it on my butt. The other trick is to be sure to turn your shorts inside out when washing. With a dozen shorts, I always have dry ones. But if you only have one or two, yes, use the dryer.
— Tom

Dear Tom,
Not that it makes it any less difficult to bear, I think your condition is quite rare, given that there are lots of riders doing similar things without the sensitivity. Here are a couple of responses to your questions from clothing brands. I expect more responses and will run some of those in the future.
― Lennard

From Shane Cooper, founder of DeFeet:
On rashes and allergies, I am not as confident to advise. I will say Dave Zabriski has issues so bad that he started his own company…DZ NUTS. I find his product excellent. On the short side of things, as you and I both know, Lycra is Spandex, and it is needed to make road shorts. I think some folks have a reaction to spandex. In my opinion, Assos uses the highest quality spandex to make their shorts. I always use their lower-end product. A wool cycling short, hmmm…not so comfortable. The indoor cycling area has exploded, as you and I used to only ride indoors for an hour…the Zwiters are spending much more time on their bikes. Sweating way more than outdoor cycling. When I do Zwift, I use a cycling liner short and UnDlite top. I look like a triathlete from 1990. But it is way more comfortable.

As for sweaty hot feet, our new lightweight vented Evo Ventoux is the best feeling sock for the hottest summer days.
— Shane, DeFeet

From Drew Bourey, founder of Bouré Bicycle Clothing:
I’m not too wise on such things, other than the fact that spandex is a polyether-polyurea copolymer and is somewhat similar to latex, which is considered a polyisoprene… and that people are typically allergic to the proteins found in natural rubber latex. So, while I have some customers who are particularly sensitive to the rubber in the leg elastic, they seem unaffected, or at least less so, by the spandex in the shorts themselves. Unfortunately, that’s about all the useful knowledge I have in my brain, and I’m not sure who might be more informative.

On a side note regarding chamois creams, I have noted that any substance that uses petroleum-based ingredients (of which I assume Vasoline is one) can act to deteriorate the spandex in the shorts and shorten the life of the shorts considerably. And those non-water-based ones also don’t wash out very well and that build-up can cause issues, as well. Oddly, or not, I’ve probably noted more issues from people using creams than from people needing to use creams? I think in some cases because they use heavy creams that invariably form a barrier that prevents one’s skin from breathing well and their crotch gets hypoxic.
— Drew

Using petroleum-based applications on cycling shorts can decrease their lifespan considerably. Photo: Courtesy Team Sunweb

Dear Lennard,
The answers from Hugh Walton are both interesting and certainly go deeper in explanations. I guess I should not be surprised at the many layers and complexities.

With that said, I would be surprised if more conversation does not take place. Yesterday I skipped past my bicycles to instead spend the day riding my motorcycle. Comparing my preparation, getting ready to ride a bicycle or motorcycle is remarkably similar in that both involve specific shoes, specific clothes, a helmet, and gloves. Comparing riding, aren’t both also very similar in how a rider is exposed and interacts with the elements and conditions? Obviously, speeds are different, but I thought of the commercial sometime back during the TDF where Jonathan Vaughters compared crashing to jumping out of a 30-mph car in your underwear. Why would anyone do that? How stupid. Yet cyclists basically put themselves in this position every time they go out for a ride.

There’s a saying in motorcycling that you dress for the crash, not for the ride. In cycling, it seems to be to dress for the ride, don’t think about crashing.

I understand the points made by both Hugh Walton and Shane Cooper, but I still remain convinced, perhaps even more, that the cycling industry has not devoted the time or resources to seriously develop meaningful protective clothing/gear for cyclists. Yes, it requires investment, but so does Bluetooth wireless shifting, complex, wind-tunnel-tested carbon fiber layups, and countless other innovations. And no, I do not foresee a future of leather-clad, heavy booted cyclists that look like the Michelin Man. What I would hope to see is really anything designed with safety in mind.

I’ve been fortunate to have two crashes involving motorcycles. In both cases, I walked away without a scratch because of protective clothing. I have scars on my knees, elbow, and shoulder from road rash from cycling crashes.

I realize my comments are naïve, but I cannot help but wonder if the industry devoted more attention to safety 30 years ago, where would we be today?
— Peter

Dear Peter,
It’s a worthwhile goal to pursue, that’s for sure.
― Lennard

Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder ( and purveyor of non-custom huge bikes (, a former U.S. national team rider, co-author of The Haywire Heart,” and author of many bicycle books including Zinn and the Art of Road Bike Maintenance,”DVD, as well as Zinn and the Art of Triathlon Bikesand Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.” He holds a bachelor’s in physics from Colorado College.

Follow @lennardzinn on Twitter.