Background: A year or so ago, I noticed that a pair of bib shorts had a spot of deterioration on one of the thigh panels. Basically it was a round spot where the outer weave had apparently disintegrated. I thought about it and decided that a drop of chain lube must have damaged the fabric. Meanwhile, the shorts were washed in the same way that I've been doing this for years. The thing is... I continue to get these spots of deteriorating fabric. It's only on the front leg (thigh) panels and nowhere else.

Considering the location and pattern of the fabric damage, the only thing that seems logical is sunscreen dripping from my face to the shorts. The problem looks like drops that expand and grow from the original drop.

So, what damages lycra? Or cycling clothing in general?

I have quite a bit of cycling and other sports gear made of similar fabrics which have not had this problem. This is really a puzzle. The gear is expensive and I'd just as soon that this not happen.

  • What type of Lycra? Polyster or Nylon? – Joe Phillips Oct 27 '10 at 15:23
  • I wear normal pants over my cycling bibs/leg warmers. Makes me look Fredlike, but gives me pockets. Also protects the elastic from oils and abrasions in a collision/fall. – Criggie Jul 13 '17 at 22:49

Lycra (spandex) comes in two forms as far as I know: polyester-lycra and nylon-lycra. Polyester based lycra will withstand harsh conditions whereas nylon based lycra will not.

Polyester is hydrophobic, meaning it does not absorb water. This means that when it is dyed, only the color of the dye dissolves into the fabric (not any water-base), making the dye permanent. Nylon® possesses hydrophilic qualities (that is, it absorbs water). Its inability to repel water causes the fabric to swell and ultimately weakens the molecular structure. The dyestuffs used on nylon® tend to oxidize, a reaction which is catalyzed by light. The microscopic effects range from color fading to complete degradation of the polymer matrix. This is why the colors fade in nylon-lycra® swimsuits over time, but do not fade in polyester-lycra® swimsuits (Man-Made Fiber Yearbook, August 2000).

See the Fabric Information Guide for more information


How old are the pants? If they are more than say 5 years old and you use them a lot, my guess would be that the sun's UV rays are causing the elastomer's to break down and slowly deteriorate. Same thing happens to old rubber bands (lycra is, to be overly simplistic, just rubber and cotton woven together). It would make sense that they would first appear on the top of your thighs as that is the spot that is in the most direct sunlight.

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    Note the original question: "Background: A year or so ago," – user313 Oct 26 '10 at 4:50
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    @wdypdx22, "Background: A year or so ago, I noticed that a pair of bib shorts had a spot of deterioration on one of the thigh panels." Do you mean this was the first time you noticed the deterioration, or was this when you bought the pants? Two different things. – Ben Oct 26 '10 at 20:13
  • if it were UV, the shoulders or the butt panel would deteriorate before the thigh panels. – David LeBauer Dec 2 '10 at 5:49
  • @DavidLeBauer in general, we know that UV light can slowly degrade many types of polymers by attacking the bonds between carbon atoms. I would give credence to the UV hypothesis. – Weiwen Ng Jun 26 '20 at 12:01

Is it always in the same spot? Do you have a piece of gear that rubs in that spot? I know I have a jacket and if I'm not careful with the zipper I get wear spots really quick just above my crotch. It sounds kinda like what you're describing.

  • No, not the same spot. It was one spot, now it's several. Only on the front thigh section. I ruled out toxic sweat since I have thoroughly impregnated the entire set with sweat on rides in the summer. The problem looks like expanding drip marks in a few areas. – user313 Oct 26 '10 at 4:55

I've wiped excess sunscreen countless times on my cycling shorts with no ill effects. Same goes for sweat, chain oil and miscellaneous grime picked up on roadside repairs.

My cycling clothing wears out from friction (simple things like a camelbak slowly rubbing holes in backs of jerseys, to obvious ones like accidental high-speed contact with asphalt) and from general wear & tear. Lycra definitely loses its stretch over time too. And watch out for loose velcro straps, they can tear up lycra and jerseys during a ride or in the wash.

  • Not friction. I added to my original post. – user313 Oct 26 '10 at 5:00

This is so old, but I have had the same issues with my own shorts and it appears you didn't find an answer, they tend to either disintegrate in the back above the butt (one of the worst places) or along the legs over time.

Grease, oils, lubricants and other petroleum based products will break down the elastic, etc in your shorts. I have found my shorts started disintegrating above the butt a couple weeks after I rode a bunch of miles in the rain along wet roads. The oils, dirt, lubricants, etc that washed up from the road during my ride got all over the back of my shorts, causing the elastic to break down, within just a couple weeks.

I have experienced this with all my shorts. I am more certain that it is petroleum based products because I had a pair of shorts for only about two months, apparently wiped some grease i got on my hands onto my shorts during a ride and now have a 4 finger handprint on my shorts where the elastic has completely disintegrated. This has happened time and time again, typically after a few months of owning, but no more than 6-8 months.

I no longer ride out in the rain and am super careful of getting anything on my shorts. Average lifetime of my shorts has extended from approx 8-12 months to about 18-30 months.

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    Welcome to the site! Answering old questions is definitely not a problem, as long as you're not just duplicating the existing answers, which you're not. And lucky you, having the option to not ride in the rain. :-) – David Richerby Jul 13 '17 at 12:10

I have some shorts that have worn in one spot, and I have worn them less then 10 times.

(someone?) said that it comes from friction, but at the front of my leg?

So now the shop say it's from friction in the washing machine. That could be the cause of your clothing deterioration.

  • Welcome to the Bicycles Stack exchange site! Please do read our FAQ, as this is a question and answer site. Normally, we would consider this to be another question, and we’d say that you should ask it separately. However, your post does actually contain an arguably correct answer that nobody has said outright: friction in your washing machine. Hence, I’ve upvoted this. Note that by SE rules, we may still elect to close this answer. I’d recommend you edit the post to say outright that friction in the washing machine is one likely cause! – Weiwen Ng Jun 26 '20 at 11:59
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    A washing machine would cause damage all around the item though? Not just in one panel, unless that panel is a different material ? Machine washing can certainly damage clothing, that point is fair and reasonable. – Criggie Jun 26 '20 at 12:23
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    @Criggie Maybe a better way to phrase it is this: machine washing will release microfibers from synthetic material. These wash out into the water supply. However, the user should perceive that as the fabric getting thinner over time. This doesn't necessarily explain why we might wear one section out first, but perhaps the sections with the lightest fabric wear out first, or maybe the washing out process isn't guaranteed to thin the garment uniformly. NB: we should still wash our clothes. nature.com/articles/s41598-019-43023-x – Weiwen Ng Jun 26 '20 at 14:16
  • @WeiwenNg thats a good answer there - consider if you want to add it as a new entry. – Criggie Jun 26 '20 at 23:35
  • I've had a go at clarifying this answer. Feel free to edit further for improvement. – Criggie Jun 28 '20 at 6:42

This answer generally focuses on how to reduce wear on cycling clothing during washing. I am not convinced that spandex or other synthetic fibers would be damaged by chain lubricant or sunscreen (as in I don't think those substances cause the chemical bonds to deteriorate, whereas chlorine will attack some synthetic fibers and weaken them over time; naturally chain lube will stain a lot of things including lycra). I believe the OP's clothes simply wore out during the regular process of washing.

Researchers such as these ones have shown that when you wash clothes with synthetic material, the process washes out little bits of synthetic fiber. This happens every wash. Tangentially, there's a public policy issue here, because those little bits of plastic fiber end up in the water supply, and from there they end up in marine life. That plastic then functions as an endocrine disruptor, with potential consequences for the life cycle of marine life - and we get a lot of our protein from marine life.

Back to the topic at hand. Logically, if the fibers in your synthetic garments are getting thinner and thinner each wash, then the garment will wear thin eventually. Presumably, the thinnest parts of the fabric would go first. Alternatively, perhaps the garment sustained some abrasion in the wash as it rubbed against other clothes, but the general wear process described above could still be a contributing factor.

How might one maximize the life of synthetic garments? It seems like careful hand washing and line drying might maximize garment life. However, this really does not seem practical on a large scale. I just tried it for a couple of my pricier kits. I submerged the clothes with detergent, agitated them occasionally but otherwise let them sit for about half an hour, then I rinsed and line dried them. They smell fine now, so clearly the process worked. However, this did take some time, and the garments did drip a fair amount of water onto the floor. I could have wrung the garments more thoroughly, but I would assume the process of wringing is what creates this microscopic damage to the fibers. In any case, most households are unlikely to have the time or inclination to do extensive hand washing.

One paper found that front-load washing machines emitted far less fiber than top-load ones. Front-load machines are more energy- and water-efficient as well. A webpage for surfers proposes that we also use cool water, use the delicate cycle or otherwise shorten the cycle time, and that we skip the spin cycle if possible. I believe it's well-recognized that you shouldn't run athletic clothes through the dryer, as heat can damage lycra, but regular dryer use should accelerate the general wear process I described above.

NB: line drying as a general practice takes a bit of time out of your day, but it does save energy; I line dry for the most part and use the dryer to selectively freshen up clothes that need it. Using cool water for most or all loads also saves energy, and most new washers and detergents are designed to not require hot water. Also, switching to cool water doesn't require any additional time on your part. So, perhaps readers should do at least this step anyway. You should be line drying athletic clothes, but perhaps readers should consider line drying as a more general practice.

Last, it may also be worth using a mesh bag for delicate items like athletic gear. These bags protect their contents from abrasion by other items in the laundry. This might not affect the wear process I described earlier, but it could reduce the overall amount of wear to the protected items.


I believe that inferior product may be the answer. My daughter has two pairs of bib knicks from the same company worn the same amount of time, both gentil cold wash (no detergent) both hung to dry undercover. One pair has the spots of thinning material and the other does not. The only thing different between the two pairs is the batch. Two different colour trims would indicate to me different batches of material used at possibly different manufacturing dates. Both pairs are 4 months old and were $180 each.

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