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Inner side tube punctures
Hi.
I have been using a bike extensively over some 5 years, then i left it for about 2 years to stand with flat tires and haven't been using it. When i decided to put it back to life so to speak and ride it again i am getting problems with inner tube punctures on a back wheel almost on a daily basis. I am not too heavy (about 95kg). So.. i watched various AI suggestions of what can be the cause of this problem and mainly it points to a probable need of change of a rim tape. But when i inspected the rim tape i haven't found any obvious sharp or loose spots which would make obvious problem areas. When i inspected two tubes that got flat one puncture is right near, you could say, almost on the valve point (from the inside of course looking towards the rim not the road so to speak and the puncture on the other tube is also near the valve but not so close, so apparently its not a single weak spot). I really don't have any experience in repairing but i would of course like to solve this problem. So from what i have described, should i try to temporarily use a duct tape before i get a better solution or from my description the problem could be something else entirely? Thanks for any suggestions and possible solutions -) |
The location, size and shape of the holes/punctures tell a lot, without better description of the holes I don't see being of much help. Rubber does degrade with time and can start to crack with it's being bent and stressed (like sitting of flat tires). Tubes leak air naturally, just at a rate that most won't call "being flat" but still enough to have the suggestion of frequent pressure checks making good sense.
Punctures along the tube's sides can suggest a tire sidewall issue or riding with too little air pressure (pinch flats). But could have other less common causes. I can't see the rim strip having any influence of this type of flat. Punctures near the valve might be simple poke throughs from some object or indicate a seating/fitting issue between the tube/tire and rim. But the base of the valve is a common spot where the tube won't always fit snug down against the rim's interior and can cause the tube to expand (like a balloon) into the gap. This spot will have a wall thickness, of the tube, that is now thinner and can easily burst (like an aneurism). When mounting the tire seating the valve down against the tire's beads and/or the rim helps limit this. There are many times where novices can't find the causes of their problems but if an experienced person were to have a look the solution would be had fairly quickly. Is there a friendly bike shop near you? Andy. |
15 years ago, I would have sworn I knew everything there was to know about flats and changing a tire. However after a rash of flats, I found out I had developed a bad habit when installing the tire. So while you do need to learn how to do the forensics to determine why a tire flatted. Don't eliminate yourself as being the cause.
In my case, I was just in too big a hurry and the tube was getting caught between the rim and the tire as I rolled the bead of the tire on the rim. Sometimes that resulted in a immediate flat when inflated. And other times I'd get a 1 or 2 rides before it flatted. |
I posted this a couple of years ago in response to this same problem. The TL;DR version is to use larger tubes that are closer to the size of the tire.
Originally Posted by cyccommute
(Post 22208388)
I might have agreed even a few months ago. However, nearly every flat I’ve experienced over the last year have been on the interior of the tube…i.e. the rim side. I’ve changed rim strips from cloth Velox just in case there was something in the tape. I marked the tube with direction arrows and clocked my tubes to the label. Nothing seemed to work. I still experienced internal pinhole flats.
About a month ago, I went through flat hell in Wisconsin and Michigan while on tour. I experienced 8 to 10 flats of exactly the same kind including 4 in a single day. One of them was on one of the few really nice downhills in the U.P. in Michigan. I did a quick dodge around rumble strips to get out into the lane rather than do 20+ mph on a very narrow shoulder. The picture below is typical of Michigan’s rumble strips. https://cimg0.ibsrv.net/gimg/bikefor...ffcbaa01e.jpeg I experienced a blow out…which is very scary on a loaded touring bike at normal speed and petrifying at high speed. When I took the tire off, there was a rip on the inside of the tube about an inch long. After changing my bike shorts (:rolleyes:), a light bulb went off. There is no way that I could have had anything inside the tire that would cause the tube to actually rip. I eventually decided that what had happened was that the quick steering to avoid the rumble strips had allowed the tube to be pulled too far in one direction. The rubber was obviously thin on the rim side and it tore due to the extra force on the rubber. I have, in the past, been a proponent of using smaller tubes. They are lighter to carry and rubber expands to fill the space. I didn’t, however, take into account something that I’ve noticed when pumping up a tube outside of the tire. Tubes tend to expand more on the outside of the torus that is the tube than on the inside of the torus. If the tube were a straight pipe, the pressure expansion would look a bit like this (please excuse the extremely simple drawings). The pressure would expand equally in all directions and the tube (pipe, actually) would expand equally in all directions. https://cimg6.ibsrv.net/gimg/bikefor...989ba59ff.jpeg But in a torus shape, the outside edge expands slightly more than the inner edge like in the diagram below. The inner edge doesn’t have room to expand as much as the outer edge…it packs up a bit more. You can observe this when you pump up the tube outside of the tire. https://cimg7.ibsrv.net/gimg/bikefor...0282336c1.jpeg Now think of the tube in the rim, especially if the tube is a smaller sized tube. When the tube is put in the tire and filling is started, the tube expands towards the tire first. Then as the tube fills, it expands into the rim channel. The outer part of the tube is trapped against the tire and the inner part has to expand into the channel where it thins. I suspect (but can’t really prove) that the tube thins a lot and, rather than the tube being punctured, the tube tears and creates a pin hole. https://cimg8.ibsrv.net/gimg/bikefor...4921d6345.jpeg My solution was to replace my 23/28mm tubes with 38/44mm tubes. The wider tubes had more material in the channel and were less prone to tearing. The proof of this idea was that my inner punctures disappeared at about the 1/2 way point of my 1200 mile tour. Going forward, I’m going to stop using small diameter tubes and use wider ones. Here is a better cross sectional representation of what is happening https://cimg8.ibsrv.net/gimg/bikefor...503fc8ae9.jpeg When the tube is filled, the tube expands in the direction of the red arrows first. Once the tube is up against the inner part of the tire on the tread side, the tube epands to back fill the rim channel. The inner part of the tube thins more than the outer part and is stress more which results in tears. |
Originally Posted by Andrew R Stewart
(Post 23702652)
The location, size and shape of the holes/punctures tell a lot, without better description of the holes I don't see being of much help. Rubber does degrade with time and can start to crack with it's being bent and stressed (like sitting of flat tires). Tubes leak air naturally, just at a rate that most won't call "being flat" but still enough to have the suggestion of frequent pressure checks making good sense.
Punctures along the tube's sides can suggest a tire sidewall issue or riding with too little air pressure (pinch flats). But could have other less common causes. I can't see the rim strip having any influence of this type of flat. Punctures near the valve might be simple poke throughs from some object or indicate a seating/fitting issue between the tube/tire and rim. But the base of the valve is a common spot where the tube won't always fit snug down against the rim's interior and can cause the tube to expand (like a balloon) into the gap. This spot will have a wall thickness, of the tube, that is now thinner and can easily burst (like an aneurism). When mounting the tire seating the valve down against the tire's beads and/or the rim helps limit this. There are many times where novices can't find the causes of their problems but if an experienced person were to have a look the solution would be had fairly quickly. Is there a friendly bike shop near you? Andy. So judging by this, if this is really the case, i frankly don't know how to adjust the spokes, and could i potentially do some damage if i make some mistake with it. If this seems familiar to someone please respond, thank you. And even if this is the only problem, should i add lets say electric tape over the old tape just to make everything more secure? |
Most bicycle wheels will have rim tape covering the spokes or spoke holes if a double walled rim. Which is common today. Lower end bikes from the vintage days did tend to come without such or used a rubber strip that by now will have long since rotted and fallen off.
If you have a rim that the spoke nipples are exposed on the inside, then you should definitely use rim tape or perhaps fashion another strip of rubber from a old inner tube to cover them. If any of the spokes are protruding from the nipples, then that needs to be addressed before you install the tape. If it's a double wall rim and the spoke nipples are not exposed, then it also needs tape or maybe one of the inserts made for some rims. |
Originally Posted by Krijes
(Post 23702742)
.....if this is really the case, i frankly don't know how to adjust the spokes......
You'll reduce tension which lets the wheel go out of true. Trying to compensate for that and you end up with a wheel with unbalanced spoke tensions and wanting to go out of true every time it takes a knock. IF your spoke is too long, grind off the protruding part with a Dremel tool or similar. Your spokes should all have the same protrusion per side. If they vary, somebody probably tried a ham handed truing job without seeing "the big picture". Use your search engine for single wall & double wall rims. IF yours are double wall, your spoke would probably run out of threads before it could protrude. I once ran into an old tube that had tiny specks of what could basically be described as "carbon". I'd patch a hole and when inflating, it'd produce another hole or 2 near the patch. After 4-5 patches, I tossed the tube for a new one. You said the bike sat for 2 years, but how old is the tube? |
Originally Posted by Bill Kapaun
(Post 23702863)
You don't "ADJUST" spokes on a properly spokes wheel.
. You said the bike sat for 2 years, but how old is the tube? First, tomorrow i will remove the tape and see what is going on underneath. I will probably send a photo so someone can give me an advice on what to do exactly. I already ordered new tapes so i want everything to be done properly. Basically, messing up with the spokes means 'truing' the wheel, something i had no idea about till now. In any case i will remove the tape tomorrow and see precisely what is going on under it. It's the first step to solution. Thanks. |
Originally Posted by Krijes
(Post 23702910)
Sorry i cut off most of your message just that i don't include too much of a quote in every answer. Yes, i have been searching for 'adjusting' the spokes on YT and i know what you mean now. First of all tubes were new, i planned not to have any problems as the bike was sitting flat for a while, but apparently i will have to do some additional work. Not to mention that before this i never even changed a wheel before, but now i am sort of expert in it. Ok a little joking is not a bad thing.
First, tomorrow i will remove the tape and see what is going on underneath. I will probably send a photo so someone can give me an advice on what to do exactly. I already ordered new tapes so i want everything to be done properly. Basically, messing up with the spokes means 'truing' the wheel, something i had no idea about till now. In any case i will remove the tape tomorrow and see precisely what is going on under it. It's the first step to solution. Thanks. |
No problem trimming a quote to weed out the "fluff". You may notice I did it to you.
IF your rim has a discernible brand name & model, maybe it's one that one of us would recognize and tell if it's single or double wall. That has an effect on the troubleshooting approach. I think you need 10 posts to add pics, but apparently, you can put the pic in your gallery? and someone else can look at it an post. It's been awhile since I was under 10 posts. |
Originally Posted by Andrew R Stewart
(Post 23702652)
The location, size and shape of the holes/punctures tell a lot, without better description of the holes I don't see being of much help. Rubber does degrade with time and can start to crack with it's being bent and stressed (like sitting of flat tires). Tubes leak air naturally, just at a rate that most won't call "being flat" but still enough to have the suggestion of frequent pressure checks making good sense.
Punctures along the tube's sides can suggest a tire sidewall issue or riding with too little air pressure (pinch flats). But could have other less common causes. I can't see the rim strip having any influence of this type of flat. Punctures near the valve might be simple poke throughs from some object or indicate a seating/fitting issue between the tube/tire and rim. But the base of the valve is a common spot where the tube won't always fit snug down against the rim's interior and can cause the tube to expand (like a balloon) into the gap. This spot will have a wall thickness, of the tube, that is now thinner and can easily burst (like an aneurism). When mounting the tire seating the valve down against the tire's beads and/or the rim helps limit this. There are many times where novices can't find the causes of their problems but if an experienced person were to have a look the solution would be had fairly quickly. Is there a friendly bike shop near you? Andy. Bike is about 10 years old now, perhaps really this tape stiffened or something, but i doubt it is the only problem. @Cyccommute gave a detailed description on what could be going on, he says that the rubber is not as stretchy as it once was - could be the case, but i think it could be the combination of all these factors. Also i don't know if it's possible that if a bike just sits flat the spokes may eventually 'shuffle' a little. As for the friendly bike shop near.. nah, not really. There is one person into it, but for some reason i don't have much of a confidence in abilities. Already before i posted this i was searching for possible causes using AI, so it mentioned as possible culprits - tape too old, spoke that should be made smooth if it feels sharp etc. Cyccommute made me think but i really don't know. If i am using proper sized tubes for the size of i tire i use, i really can't believe that the rubber got so bad in only a few years. It's all quite puzzling, but today i will remove the tape and send pictures via links if that is possible, just to make sure that if anything could be done in this sense - gets done. |
I took the tape off. Nothing special to see, except that one if the spoke end is for some reason moderately sharp to touch. Nothing looks like it protrudes unevenly. And this sharp end is not on the place of the two punctures.
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Originally Posted by Iride01
(Post 23702708)
In my case, I was just in too big a hurry and the tube was getting caught between the rim and the tire as I rolled the bead of the tire on the rim. Sometimes that resulted in a immediate flat when inflated. And other times I'd get a 1 or 2 rides before it flatted.
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If the rim is in decent shape, a wheel person at a LBS might not charge very much to look at and take care of any protruding spokes. If a experienced person hasn't looked at that wheel at least once in it's lifetime, then I'd further recommend it. A taco'd wheel is no fun and maybe dangerous if you are going down a twisty trail at even a moderate speed. It happens so fast you'll be laid out on the pavement before you know it if it's the front wheel. If cost is a issue for you, most all will give you a estimate or best guess. You can always walk away if it's too much for your wallet.
The fact you have a spoke sticking beyond the nipple suggests that someone has been willy nilly tightening spokes not knowing enough of what they are doing. |
Originally Posted by Iride01
(Post 23703611)
The fact you have a spoke sticking beyond the nipple suggests that someone has been willy nilly tightening spokes not knowing enough of what they are doing.
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