I partly disagree on that view. Carbon fiber itself can handle high temperatures therefore carbon clinchers would be totally fine if adequate matrix would be used. I see another possible measure in modifying braking system (wider braking tracks that extend below the lips and larger braking pads). But hey, it is easier to use cheap epoxy, slap on steel discs and sell that stuff for high price.
@@alexeevfrancoismendoza1891 You need to take in account complete system though. Disc brake race bike (weight around 7 kg) is way more expensive than counterpart with rim brakes.
@@jkk916 we are talking about the cost of wheels, besides there are DB bikes that's are cheaper than there rim counterpart so your argument is flawed. You're just not picking.
@@alexeevfrancoismendoza1891 In fact your argument is flawed. You cannot use wheel without whole system (frame, DB groupset etc.) so the price of the wheel alone means nothing. Unless you want to play frisbee. Also, please show me race worthy DB bike that does not cost a fortune. You could use aluminum frame and ultegra groupset and still be reasonably near weight limit. On the other hand, DB bike would need carbon fiber frame and dura ace groupset for similar weight. Plus DB groupsets are usually more expensive then rim brake counterparts.
Great, informative video. Nicely done. You have left me wanting to take an infrared temp gun with me on my next ride so that I can bomb down a local hill, immediately jump off the bike and check rim temp. I too have knock-off clincher carbon rims and have always wondered what its limits are as far as how long/how steep a descent can be.
@@smallhatshatethetruth7933 - Another thing that must be said is that aluminum rims brake so much better with rim brakes that it is shocking the first time you change from one material to the other.
yup i see all the vids now are about how amazingly strong they are....90's..i had a decade of carbon wheel fail vids before the marketting took over the internet 🤣 0 faith for carbon rims. also not sure ive ever seen a carbon wheel that hasnt got bubbles and kinks and flakes hidden below the gloss. (its not just the cheap brands the big players have the same issues)
Great synopsis! I put some thought into buying carbon clincher aero wheels but couldn’t come around to getting due to heat buildup and dissipation of the carbon brake track. Didn’t seem like a good idea in the SF Bay Area. Ended up getting Shimano wheels with the aluminum braking surface.
Great analysis, really enjoying your videos! One small thing to pick at though: not sure it's quite so simple to say that braking goes up with the square of speed... Kind of depends on the situation. For example, it holds true when decreasing speed by delta "v" that the total energy imparted into the brake system is a v^2 relationship. But that's not usually the instances that matter for this type of rim destruction (total energy input is pretty low). You'll put a whole lot more energy into the system on a sustained descent - for example if you're heading down a mountain and try to keep a constant speed (where you might not have any hairpins requiring intermittent heavy breaking to decrease your velocity). In that instance, if you're maintaining your speed, an oversimplification is that brake power is linear to velocity (P=F*v), and total energy input is obviously just that brake power multiplied by the amount of time you spend putting that power into the system. Expanding on that a little more, for bicycles there is actually a noticeably less-than-linear relationship in that constant-speed-descent scenario, thanks to aero drag. Aero drag force goes up with v^2, but the power goes up with v^3. The impact this makes on braking is obvious when you hit a terminal velocity on a 10% grade somewhere around 40-45mph if you're not super aero. To maintain that speed, zero braking power is needed, and obviously to hold zero velocity on the same downhill grade requires zero braking power (and really a pretty tiny braking force for rim brakes, thanks to the enormous moment length - on the order of 10N-20N even on steep grades). So based on those two extremes, a brake power vs. speed plot would have a hump shape, and brake force would decrease as speed increases. I had to think through all of this recently for my wife's sake - we live near mountains, and she is a brand new rider needing to build confidence. She has short fingers, and on Ultegra 6700 levers she could barely reach past the lever pivot, and thus really struggled to generate braking force. It took a little thinking to understand the somewhat counterintuitive notion that while it feels safer to maintain less speed down a hill, it takes quite a bit more brake force to do so, causing hand fatigue. In her case, it turned out that ST-785 levers have MUCH better geometry for small hands (pretty similar to GRX lever pivot location, which they use as a marketing point for that groupset), and of course the more efficient force transfer/brake torque generation between hands and tires of hydraulic disc brakes added to the confidence factor. I piqued my own curiosity enough to throw together a quick spreadsheet, with some rough guesses at constants; I assumed elevation of 2000m, like where I live, to give a sanity check of the constants - terminal velocity of 41mph at 10% grade is pretty close to reality for me, at least close enough to show the relationship. Here's a link to the output plot: i.ibb.co/mGkkfCp/braking.png
to slow down, the energy you need to take away from the bike over a period of time, is proportionate to the kinetic energy you need to absorb from the bike, over the same period of time. and kinetic energy of the bike is proportionate to the square of velocity. remember to consider potential energy in the equation, if you are on a free fall.
Have seen this exact same bulging at the brake track with a Selcof wheel i told the customer to send it back for warranty and planet X sent him a full new set of wheels. He's not a small rider i'd say around 13st but not a big guy and he's not shy on a descent so not a lot dragging the brakes.
especially interesting in the context of randonneuring, where I find specific recommendations against carbon rim brake setups due to long, moderately loaded descents
Informative video. Thanks. Always hear to be wary of carbon clincher for rim brakes on long descents/heavey braking. Would releasing air pressure in the tires after a ride help reduce the side wall pressure?
Having owned a shop for a few years, you see this a lot. I’ve not seen many problems on short steep descents, but on longer descents there is just nowhere for the heat to go. Carbon just doesn’t conduct heat away from the brake track well enough. We’d see it most often in the summer when relatively inexperienced riders would go on trips to the Etape or Maratona (or similar). Hot days, long unfamiliar descents and large groups of riders (where you often have to brake so you don’t crash into someone) are a recipe for delamination and melting resins. I’m all for decent alloy rims for safer riding in big mountains with rim brakes. Disc brakes eliminate the rim issues, but even they can overheat.
Nice!. The stares I get when they see my early 1990s MAVIC SUP Open 36h with all the dark anodization eaten away from my brake pads. Straight gauge spokes yet ONLY laced 2x...strong as an bear and still true. Oh, I mentioned they were laced 2x not 3x...strange!
What's about carbon rims with aluminium brraking tracks? Looking for deep section wheels for my TT with rim breaks and want to avoid the amount of work by gluing tires.
On a TT bike it really doesn't matter. You probably won't go down big mountains on that. Disc brakes on TT/Tri-bikes are the biggest joke in the cycling industry.
Very interesting. I stumbled on this video after delamming/destroying a carbon clincher 3min20 into a -5% descent as a 75kilo rider this past weekend at IM CDA. I knew that they *could* fail, but I had no idea that that was in the realm of a potential failure. Sketch.
I wonder if the wheel was slightly out of thru and that means that the rim was rubbing on the brake pad every revolution on the same spot, and that lead to the over heating on that zone and cause that problem. I say that because the rim was out of shape in on place and not the entire rim, if it was the entire rim the tire would pop out for sure. i think this makes a lot of sense, for this situation.
I live in Menton near the famous col de la madone and have melted two different brands of climcher as certain descents just need you tonrest on the brakes, which carbon doesn’t tolerate. It really knocked my confidence and speed so ive gone back to campy alu wheels until I can buy a nice disc bike
@@davemoss6976 I love my disc brakes. Sure they might be higher maintenance, or you need to be more careful when transporting your bike. But I once eliminated the scratching and haven't had it since then anymore. Plus it gave me much more confidence in descents, because the breaking power is so much higher.
Dragging brakes is the wrong thing to do. If you start from a standstill at the top of a slope and you want to come to a stop at some point on the slope, all of the additional potential energy you have at the higher position must be converted into kinetic energy and then dissipated before you come to the lower position. There are two methods available to the rider to dissipate his kinetic energy: converting into heat via the braking system or increasing aerodynamic drag. As you probably know, drag goes up with the square of the speed, so the higher the rider's average speed, the more energy is dissipated via drag, reducing the amount that the brakes must to convert into heat to bring the rider to a stop. If we extend this line of thinking to multiple braking periods, the principle is reinforced by the need for cooling the brakes. All types of bicycle braking systems are cooled by ambient airflow. The faster the airflow, the greater the cooling effect. In conclusion, be as unaero as possible and brake for the shortest time possible.
@@Catcrumbs I know its an old comment, but the energy doesn't go up linearly with the speed. So if you keep your speed generally lower (by dragging the brakes), wouldn't this decrease the overall energy required to stop? So basically the question is, is the energy required to go from 60-0 bigger than the energy required to go from 30-0 a couple of times? Maybe im totally wrong, but an experiment would still be cool to see.
@@onezweithree Remember the conservation of energy. More energy does not materialise as the rider goes faster: the kinetic energy has been converted from the potential energy of the rider when he was at the higher altitude. In other words, the speed achieved reflects the energy of the rider, not vice-versa. Maintaining a given speed on a descent requires work to be done by the brakes. Whether the rider drags his brakes or not, ultimately the same amount of energy must be rejected by the rider (either through the brakes, aero drag or other means) to come to a stop at a given point. As I said in my earlier reply, travelling at a higher speed results in more energy being dissipated via aero drag, reducing the work that the brakes must do. Lets examine your hypothetical. Say we have a rider with a terminal velocity of 60 km/h for a given slope. Once he achieves TV, any additional potential energy is being matched by the energy he is dissipating via aero drag (and rolling resistance, bearing friction etc, but lets ignore them). His brakes are doing no work until he begins to slow from 60-0 km/h. Now lets say a physically equivalent rider loses his nerve at 30 km/h and will freewheel up to that speed before braking to a stop and repeat this process until he must stop at the same point as the braver rider finished (imagine there's a brick wall on the slope both riders intend to stop short of). In terms of kinetic energy, the brakes of the rider stopping from 60 km/h would do as much work in one go as stopping from 30 km/h four times, due to kinetic energy going up with the square of speed, as you hinted at. Remember though that the ultimate source of the energy in this case is the potential energy of the rider in the initial state. The braver rider gets the benefit of increased aero drag (going up with the square of speed) at his higher speeds, particularly at TV. The energy rejected this way still has to be dealt with by the cowardly rider through his brakes, so under real conditions in an atmosphere, a rider unwilling to ride at higher speeds will have to do more work with his brakes than simply examining the kinetic energy at the two different speeds would suggest. I wish I could have put this more succinctly, but I hope this explanation is understandable.
I have swissside 80mm full carbon on my TT bike. Not much braking happens on this! Shimano c50s on my road bike, solid, good braking and shallow enough that they are suitable in all weathers
Are you saying that manufacturer's claim that they have speical, heat resistant brake tracks are false? Take for instance Mavic and their iTg max brake track.
Very satisfied with my HED Jet wheels which don't have these safety issues. He of the Princess Blanket said their aero performance, although not the best, is still pretty good.
Not to argue against the point made, but isn't there also an issue with tubular tire glue coming apart due to braking heat? I remember an article a few years ago talking about it happening on one of the longer giro descents.
I know very little about carbon wheels, but have a fair ammount of experience in laminatling with pu and epoxy. When advised that I should upgrade to carbon wheels this has always posed this question. Friction through braking will always generate heat, and I've never been convinced that the resins used can 100% cope with this without softening and potentially deforming. So until I make the move to disks I can't justify the expence.
High temperature is also why you should avoid Lezine glue based tube patches no matter the kind of rim you use. I used this product once to quickly fix a puncture on the top of the Tourmalet and I almost lost control of my bicycle during the descent when the patch glue melted and the tire suddenly lost all its pressure.
So, can you heat the warped carbon rim to reshape it? I'm assuming the resin, when cooled, regains its strength. Or does the heat cycle fundamentally alter its properties?
No. You can not reshape the cfrp rim. It is thermoset polymer, heat cycle will alter the properties in a bad way. Cfrp clincher rim is not ideal for rim brake.
Have you commented on hooked vs hookless clincher rim designs? The hookless trend seems to bring a lot of compatibility issues and I'm not really sure what the benefit is at all.
That's the reason why I ride 42 mm mid-depth aluminum rims. The weight is still relatively okay with 1.85 kg, still a huge improvement from the 2.15 kg standard rims that came with the bike.
The Giant SLR1 30mm Carbon Clinchers (that you have done a review video on) are claimed to use a resin with Tg of 245c. Does that sound right to you? Just asking because I’ve been looking at buying a pair, especially after seeing your review of them!
I've never had a problem with them, but I've never ridden them on massive descents, and im really heavy. Out of all the carbon rims I'd probably trust them the most. Fine for flat riding. Everything else about those wheels is top notch.
Good video as always. My two cents: 1) I give them the benefit of the doubt with the offset nature of the reinforcement of the spoke area of the rim. I've seen super cheap rims come with stickers on the rim bed noting drive side direction, suggesting even a symmetrical rim has some reinforcement for the offset forces of a rear wheel. 2) Maybe someone can come up with a direct-mount brake standard that moves the braking area down 20mm. Problem (mostly) solved.
The sticker normally helps you start to lace the wheel and the spoke holes are normally drilled at an angle (greater angle for NDS). If you drop a loose spoke in and pull it side to side you'll see the angle where it rests best (even though the holes are on the centre line). 2. Alot of factories are really pushing the limits with making the clincher hook shorter and lower down (so reducing the height of the unsupported bit), this is good but it does make the tolerance tight of some tyres being easy to fit and some hard.
Must admit sold my carbon clincher rim brake wheel and went back to my trusty jetfly wheels not lightest at 1425g but light enough.i wont buy a disc bike only because I would have to buy a lesser bike but pay alot for it .mine is only 6.9kilo how much would it be for a disc bike that light I wonder but they are nice
Nice video, this is a well known problem, and has driven the move to disc brakes. I have a question what do they use in F1 in their carbon disc's? I'm sure they don't tell the driver to go easy on the brakes.
@@PeakTorque Actually in F1 and airplanes its carbon-carbon. Ie the its carbon fibers... in an isotropic carbon matrix! Carbon ceramics are more useful in road cars because of lower braking temps, because they aren't driven as hard.
Nice analysis on the clinchers, but you missed something regarding the tubulars- at any temperature that a clincher's resin would get soft, the glue holding the tubular on the rim has long since given up and the tire starts to pile up at the valve stem.
@@jaro6985 i was going to say same thing. Metals allow heat flow, so the maximum temperature on the braking surface tends to be lower but heat from the braking surface flows to the glue eventually. With carbon the heat leaves the braking surface slowly so that part of the rim can get really hot while the glued area is just warm.
I had a set of Token C50 carbon clinchers years ago,the front rim cracked internally on a ride,so it was hard to tell.When doing some cleaning and maintenance,something did not look right.On inspection I found the crack.So swapped it for an alloy front wheel,and used the rear carbon for the TT bike.I have stayed away from carbon wheels since,but am considering the Winspace Hypers.Tubs are lighter and ride better but are a bit of a faff with glue and stretching.Also tyres are more expensive and no one around to fix anymore.
repairing tubulars is not so hard or wasn't, but with the advent of nylon casing strands a large cut is the end of it. cotton tubs on the other hand you can pull the tread off, and remove the strands and reglue. I could make a good living repairing tubs but we now live in a throw away culture. I haven't had a puncture for 18 years using Conti 4000's and 5000's and i don't race, so that's why i haven't used Tubs since the first conti grandprix came out. In a nutshell the nylon casings offer less deformation( bulging ) on small cuts and superior protection but you just can't repair them properly. Cotton is the way to go, but have a support vehicle! i am interested as to why he didn't mention tubeless as this brings the pressure down i am going to post this at the top as well but wanted to respond to your comment.
Why you think the heat is proportional to the square of speed? I think the heat genereated by braking is proportional to the kinetik Engergy which is a linear function of mass AND speed. Regarding the brake surface, do you think it would help out the carbon clincher to move the brake surface a little bit down, away from the tyre where the brake surface is supported by more vertical material from the inside?
@@wenkeli1409 thank you. I have overlooked that and it is very counterintuitive to me. It would indicate to me, that the amount of work you have to add to a system to travel 1m/s faster is different and depending on the actual speed (no friction...). Or to put it the other way around, if you accelerate with a constant power the acceleration will decrease with sqrt 2 ..... Feels weird to me and probably mixing up Energy and Power.
Interesting stuff. Got a set of DT Swiss Prc 1400s and not had any trouble as yet but must admit I don’t feel to safe on short steep descents that call for maximum braking force 😕
I have a similar pair of wheels paired with some Swiss Stop brake pads. I've been on some decent descents and had to slow down from higher speeds. I felt the brake track at the bottom of the decent and they were barely warm to the touch.
Would this be worse with carbon tubeless? Also, is the bending for sure caused by the tire pressure or could it also be side pressure from leaning in a corner (right after braking) since clinchers the pull on the sidewall?
One question, many sportscars today and in motorsports they use carbon brakes, why doesnt they warp if a bikewheel does it under heat? is it the construction ?
@@marshallferron yes that reason is because we cant do it reliably yet, not because theyre not good. The highest level of automotive racing, F1, use carbon discs so clearly they can be made at a high level.
@@MrGarycoww how is it different than grinding away at a disc? You realize the rim has a part built in specifically for braking thats in addition to the structural part of the rim right? so when you say "grinding away at your wheels" thats inaccurate and comes out of ignorance, but sure, continue to make sarcastic rather than constructive remarks which display your ignorance
Well presented and logical analysis - thanks! Isn't there an argument to be made that rim brakes put less stress on the wheels as they don't put the brake loading through the spokes? Not sure of the magnitude relative to the loading due to weight for example, but always appeared that disc brakes are heavier and put unnecessary loading on the wheels(?)
I suppose it's because there's a thick bit of polymer between the braking track and the thin strip where the tyre is glued on. Thin strips are bottlenecks for heat transfer. Whereas on a carbon clincher rim, the braking track is right on the thin hooks, so there is little thermal barrier.
Yes. I wonder to know what the owner did with it ? To me it looks normal it failed after being worn like this. Maybe even improper pads have been used and overheat the rim.
Interesting. There are various internationally recognized standards (eg UL, IEC etc etc) that are applied to many products (eg household electrical products, automotive industry products etc). It seems the bike industry doesn't have any such thing?
Having rim braked road bikes and disc brake mountain bikes I can see the advatages/disadvantages to both. If I was head to the Alps I would fit an alloy clincher rim brake wheelset to the road bike. I have experienced brake fade on a steep mountain bike descent with disc brakes. Would be nice to provide data on temps the hydraulic fluid could comprise braking on long steep descents. A friend who has ridden both disc and rim road brake bikes on alpine descents indicated the need to change the disc brake pads frequently due to wear. He indicated if he had to choose 1 bike for alpine descents he would select the rim brake bike due to simplicity.
@@alandwyer380 It was not. What failed first was a park tool pre-glued patch in the rear. When I diagnosed the issue, I recall there being some other failures pending. This was while I was touring, on a one lane road, descending 2000 ft with an average grade of -14% with many sharp, blind corners so I was braking very heavily.
Whether you run disc or rim brakes, you still have to dissipate the same energy on a big alpine descent. Is sending it at rims and pads rather than rotors and pads actually more reliable and/or cheaper? How quickly do repeated big alpine descents wear though his alloy wheels? The cost of repeatedly changing disc brake pads may be more salient, but might the cost of more rapidly wearing through wheels, even if alloy, still be higher? Could
As you don't really see it much in the pro peleton (who historically have used tubs), I'd say it's not a significant problem. Besides which, have you tried to remove a tub from a rim, even with no glue? Once inflated it stays on pretty tight.
Not a significant problem with modern glue. Just do your research and you'll be safe if you go with tubs. Source: Running tubs for a year now myself ^_^ doing all my own gluing and wheel builds
@@GS-pk9rd On the other hand you don't see the pros riding the brakes! Civilians start getting nervous around 80 kph but pros don't. When i rode tubs 40 years ago we were told to try to slow with air drag if a descent got faster than we thought we could handle. Do not ride the brakes with clinchers on carbon rims or with tubs on metal rims.
@@HweolRidda I think most amateurs riding a high end tubular set up would also know to 'air brake ' too, I certainly do. Sure the pros are better descenders than us, but they also go faster and brake harder. For carbon applications at least, I don't think overheating glue is a real problem.
I live at the bottom of the alps, some descents are 30km long. Always used alloy rims, switched to disc last year. Now I can use carbon rims without any worries. For 300g more that's a no brainer
I ride carbon clinchers in Belgium. Last year I took the risk (they're cheaper Chinese rims from LightBycicle) and took them to the alps. No problems descending the Stelvio. I'm sub-70kg though and I keep the amount of braking to a minimum. Some other tips/tricks: Lower tyre pressure, especially up front! Make sure that the calipers touch to lower part of the braking track (as far away from the tyre as possible) and finally: cadence braking or alternate rear/front.
@@MrFornicater that's actually a great point. Long dragging breaking. And made worse by the reduction in aero drag as you're behind the cars so you need to brake even more
Not having direct experience in this aspect I'll put it to the commentators. CF resin stiffness goes south as temperatures exceeds 120C and compromises the stiffness of the CF rim. During similarly prolonged braking wouldn't an Al rim, conductor that it is, transmit that heat to the tube/tire and risk blowout? Or is that an overstated risk?
Stepping out of your scope here but I say save it - mostly for alloy wheels. At €30 - €85 a pop I can get a good rim and ride. Difficult to get a good carbon rim at those prices... Disc brakes are fine too and they have their place, so I say keep them as well. But in the real world its not superior - just different.
Nothing is fool proof there is bound to be some failures. Some clinchers have specific weight restrictions. That is why I go the extra step to inspect my carbon wheel for any cracks or unusual wear
Great analysis. I prefer to use a hybrid clincher design which combine aluminum braking surface /rim with a carbon ferring. Currently I have two sets of 60mm wheels from Fast Forward and they are superb and very, very safe. They are rated to 140kgs and can handle very rough tarmac without needing adjustment. Breaking during a decent is top notch and heat dissipation is not an issue. Carbon braking surfaces for clincher wheels just don't make any sense.
I was going to ask about this as I have carbon wheels with an aluminium brake track. So the issue with carbon clinchers is only when coupled with a carbon brake track?
@@45Camster the issue from what I understand only pertains to full carbon clincher wheels. Full carbon tubular rims seem to be okay since they don't support side walls / beads of the tire.
K Rider I bought a TT bike that came with carbon clinchers but with an aluminium brake track. I’m now using them on the road bike as well. I understand the reason behind the full carbon clinchers failing but haven’t checked the “construction” of my wheels and haven’t had carbon wheels before. Assuming the aluminium brake track extends to where the tyre bead sits preventing any overheating issues?
It's a good question, but I think that the aluminum braking track has some advantages but does not solve the problem discussed here, because the softening/weakening of the carbon rims is caused by the total heat load put into the material, not by the spot load. In other words, if the rim that failed in the video were to be cut apart in several places, the failure would be the same all the way around. An Al braking track, if sufficiently thick, could smooth out the point heat loads all around the rim, but that's not the problem. The problem discussed in this video is that there's just too much heat put into the wheel at an area that's vulnerable. The heat is put into the rim over, say, hundreds of revolutions of the wheel so it's well distributed on that brake track regardless of the Al hoop. The AL track helps with friction between the brake pads and the brake shoes, especially when wet. The Al might also dissipate heat faster than bare carbon, which mitigates the issue some, but my guess is that this difference wouldn't be nearly enough to matter. Carbon rims with an Al track still have that 'hinge' that can go soft in long-term braking.
That's why manufacturers like, say, Scope, state no system weight limit for their disc brake wheels, but limit rider weights for the rim version of the same wheel to rather discouraging digits. And that is why I, as a heavy rider, never consider rim brake wheels (besides the poor braking properties of all but hydraulic rim brakes).
I wonder how many rim brake wheelsets the pro teams throw away during and after the Tour de Suisse or the like. Post stage there must be a few that are just like this. I predict that in a few years they will all be using discs setup tubeless.
One solution: get a disc brake bike 😜 on MTB I'd never feel quite as comfortable doing what I do if I was on rim brakes, I can pretty much slam on the brakes so hard it feels like I'm gonna snap my forks with a 200mm front rotor
Glue used to attach tubular tires has a history of failure when heated due to excessive braking. Carbon has poor thermal conductivity as you mentioned. It stands to reason that once the carbon epoxy gets to a temperature and starts to soften the glue that holds the tire on will also soften. Best solution is metal rim brake track for rim brakes and disk brakes for cabon rims. Save weight, cost, and easier to maintain go rim. Disk is a good all round solution but is harder to maintain, is heavier, and can cost more. Does the average nonprofessional need carbon rims? Clincher tires? If you ride enough you will damage rims. Safe - lightweight - cheap. Pick two. The other becomes an ain't.
sorry dude, safe - lightweight - and cheap are not mutually exclusive. It entirely depends on how you use em. A good descender doesn't need much brake. A person who lives in flat land doesn't need much brake. A volvo isn't safe to re-enter earth's atmosphere with, but they're pretty safe as cars.
Tubs (glued-on traditional tubular tyres) type ride much better than clinchers - they feel livelier, and much more responsive to input effort. A good alloy rim/tubular combination is incredibly light. Disc brakes in my opinion don't work any better than a good dual-pivot side pull rim brake. Also, rim brakes are quicker and easier to fit and set up than discs. We now have thru axles - so in major races, a speedy wheel change is impossible, so the whole bike has to be swapped! Is this cycle technology progress? I don't think so.
I only ever use full carbon tubular rims or carbon-alloy clinchers. The vast majority of carbon rim failures are clinchers so I stay well away from them. The pressure of the tube pushing out, the pressure from the brake pads pushing in, and the heat created from braking all acting on a thin piece of carbon fiber is a recipe for disaster. At least if my carbon tubular cracks then I still have an inflated tyre to ride on until I slow down and stop, rather than the tyre exploding off the rim like on a clincher.
You just gave me yet another reason for staying with a steel frame and aluminum rims. I do not race, so weight is not a top priority but durability and ease of repair are my main considerations. The industry calls it 'carbon fiber' as a sales gimmick but I call them what it really is; molded plastic (epoxy). I also live in Arizona. That means any plastic is degraded by sunlight much quicker. I am just waiting for the news report where a tourist rented a carbon fiber MTB that failed on a trail with disastrous results due to sunlight degradation of the 'carbon fiber' (plastic). That will never happen with a steel frame and aluminum rims even with rim brakes.
That's pretty much my reasoning as well. While obviously heavier than a nice carbon frame, a quality steel frame can be fairly light. The last gen Cotic Soul (RIP **sniff** ) 27.5" hardtail was only ~2 kg. You can also get some pretty nice alu rims that are plenty strong. TBH a large portion of the weight these days lies in the tires; those wide 2.6" monster truck tires can easily be 1 kg a piece.
That's the best reason I've heard so far in favor of disc brakes, but rim brakes still have a lot going for them: ease of maintenance, they're quiet, can be adjusted even while riding, more aerodynamic, lighter weight, and make frames lighter as the braking force is applied more centrally (at the fork crown / top of the seatstays, vs the dropouts with disc brakes). Or maybe this vid is really trying to convince us to go tubular 🤔🤔
I like that you are a Shimano fan boy because so am I. I’ve told people over and over that carbon clincher is a terrible idea I will share this with them
This is basically a shit quality wheel. First gen carbon that melts. I ride rim brake zipps. Done over 30k kms on them and not a singe issue with rim, brake track doesn’t even wear out... this video is a bs
I have a bike with a set of shimano C75 tubular rim brake wheels. I like tubulars in general, but damn they are expensive and tricky if you puncture (superglue works... hopefully). So I thought about getting tubeless ready clinchers but in the end opted to buy a disk brake frame instead. Having just watched your excellent explanation of the failure ... I'm glad I did that.
Some brands do use higher quality resins. I'm far from lightweight, but pretty confident that I've thrown everything I can at my carbon clinchers & they're fine.
On a pair of Chinese premium carbon wheels not even a hint of wear after 1000 km. Learn to tap brake by setting your brake pads further away from the rim brake surface. This will the brake levers to only slightly contact the brake surface and thus allow for feathering the brakes. Tap braking is half braking from back to front alternating that until you stop or slow down. You can’t use carbon wheels with an improperly setup brake pad distance for rims brakes.
You’ve forgotten to note hat tubies are sewn together at the bottom. As pressure increases, they has no bead to expand outward, hence the rim doesn’t need to provide resistance to the tires expansion. This is more important that the fact that it’s glued on as you noted at about 9:11 in the video.
@@richardguggemos6336 i think i might be guilty of mixing two issues here and misunderstanding your point. the point several posters were making was that as carbon doesn't disapated heat well, the glue should be fine.
If the wheel is manufactured with a thickness variation in the brake track there will be heat buildup in one area even at low braking forces. That would be my guess in this case as its failed so gently, and not a sudden catastrophic failure.
