Can Tyre Pressure Change Due To Heat Generated By Rim Brakes? | GCN Tech Clinic

[@gcntech]

Always remember to use #askgcntech when asking your cycling-related questions!

[@DeeKayDoubleUSee]

#askgcntech Hey Alex & Ollie, I would like to ask if there is any way to keep my matte grey painted frame and forks free from scratches, stone chips, scuff marks road grime and the likes of it? Many thanks!

[@peterfranzjr.1190]

In reference to the shoes, I have a couple gravel/MTB shoes and they actually have slightly different stack height. I wouldnt switch shoes on the same bike BUT I would say you could use the same set of shoes on various bikes if you want

[@bikeanddogtripsvirtualcycling]

#askgcntech Over the past few months I have developed somewhat of an indoor (Rouvy) racing addiction with 4 to 6 races each week including two every Sunday. I often end up in a bunch sprint and whilst fairly successful in these (say 60 to 70% wins in my group - not overall race wins , just say a chase group sprint) I always stay seated because I have this fear of the bike frame / carbon snapping due to excessive movement. For reference it is a rim brake bike connected to a direto xr trainer (so QR). Staying seated I can max out at around 14 w/kg peak for about a second but feel limited. Is this just nothing to worry about - as I have seen you guys do some flat out online sprints whilst standing in the past. ta (just getting ready for a short TT (none drafting race) whilst typing this.. Stu

[@Bike4Coffee-Cake]

04:00: Love the idea that Pogacar could possibly power an eco house through his zone 2 training 😂😂.

[@FredrikGranlundkayaker]

Ideal gas law: pV = nRT. A 20 degree increase in temperature from 20°C to 40°C will cause a 6.8% increase in pressure if the tyre volume is "full".

[@janwillemkuilenburg7561]

The spoke hole puncture: a possible 3rd cause could be a sharp edge in the rim around the hole, from the manufacture process. With sandpaper you can make the edge smoother.

[@Flym4n111]

10C = 3psi isn't really how it works. Perfect gas laws says it's a percentage of the pressure. 10 degrees difference at around 20C will be 3.5% increase in pressure, so for a road pressure, you'd get from 75 to 77 PSI

[@matthewguenther6925]

This tracks. I have witnessed tires failing from temperature differentials. I participated in a Gran Fondo where the peak ambient air temperature was between 35-44 C (95-113 F) up from about 18 C (65 F) in the morning, Later in the day I heard several tires fail with loud bangs at rest stops and was riding right behind someone (small and lightweight) whose rear tire had a blow out just riding along on smooth clean tarmac.

[@RenAigu]

12:50 Wippermann Connex quick links. No tools, no click, no wear* when (un)installing, so practically infinite* re-usability.

[@SonnyDarvish]

Good to know. Also, KMC has 2 types: single and multi use links.

[@simonRt]

In my experience when riding in relatively hilly terrain it lasts around 10k km, then develops small indentation (recess in the inner surface of the link). I just replaced it for a new one for the peace of mind. Nonetheless it never unlinked on its own.

[@RenAigu]

​@@simonRtyeah tbh, I see the inner plates wearing into it a bit too, in both sets I use (I alternate chains, including their respective quick links) at 3000 km. I don't see it failing anytime soon, but it'll probably be good for the entire life of the chain, as the closing mechanism should not wear too much.

[@stephencharles6932]

Yes but the Wipperman cost is so high for what it is. Feels like I am being ripped off here. I use 5x the one use type with no isues.

[@roxstone9283]

Wippermann guarantee them for the life of the chain.

[@nickkambitis5340]

I reuse quick links hundreds of times. Never had one fail. I change with a new chain

[@philiphumphrey1548]

I think the old ones that you had to twist and bend to remove had a limited number of reconnections. The modern ones, as long as you remove them with the proper pincer tool should be good for a lot of reconnections.

[@mikehoward7777]

I use Connex links. So easy as no tools needed

[@nellyx1x493]

If you haven't melted an inner tube while rapidly descending an Alp, then you weren't trying hard enough.

[@feedbackzaloop]

on the contrary you were trying too hard. Let go of those brakes!

[@davidshardlow4369]

😂

[@lovemesomedetail]

@@feedbackzaloop on the contrary he/she was breaking a lot apparently, so maybe he/she maybe wasnt trying hard enough! ;)

[@feedbackzaloop]

@@lovemesomedetail now that is just tryhardism😂

[@robertcatuara5118]

I have twice and decided to switch back to butyl. TPU with rim brakes don't work where I ride. (Mt. Baldy, CA, Tour of California fame)

[@juliansharples1319]

Hi GCN, i used to be a pro mechanic and would advise never to re-use a Shimano quick link as they fail very quickly and could cause serious injury or worse. I have seen it with customers re-using them and coming unstuck. I have also helped people roadside who have had the same problem. You can also tell fake Shimano chains as the quick links don’t give that Shimano characteristic loud bang when you apply tension on the chain when joining. The fakes just slump onto place with little or no noise. Stay safe out there and don’t risk your life for a £5.00 quick link. Piece of mind is worth a minor outlay and just keep the new link with your spares in the bikes saddle pack or cycling wallet. Many thanks for the show, Ju👍🏼👍🏼

[@insanecomicdude]

4:00 I've thought about hooking a hub motor up to a rectifier and a charge controller and battery to make a direct drive bike generator / trainer (using the hub motor as a generator). It would be a fun project I think.

[@cyclingadventure9]

My gp5000 lasted me 7500km. I used tpu and swapped the front and rear about 4000km in. But where I live the road condition is generally very good.

[@reinholdachleitner2069]

Awesome milage,better than Michelin.👍🏻

[@LukeGJPotter]

At the Etape 2019, it was 40°C, I heard lots of people's tyres go pop on the descents. I think the Surface Temperature of the road is the most important factor in changing the PSI, as it was chilly in the morning when the Tyree were initially inflated. The heat from the rim brake can add a little extra PSI that can make an already stressed tube pop. Big temperature differences are a mega issue with Hookless, as the safety margin is so slim.

[@MartinBrown-mb7pz]

Wow, sounds horrific - did anyone die? More reason to run TL at lower pressures I guess. With disc brakes, obvs!

[@larryt.atcycleitalia5786]

And wasn't it Levi Leipheimer(?) who told riders at his Gran Fondo event NOT to show up with carbon clinchers after a whole bunch of failures on a steep descent on the route? Carbon clinchers + rim brakes should be an oxymoron.

[@Matt_Kraczon]

I vividly recall seeing people roll tubulars off the rim in tight corners of crit races in North Carolina, where I grew up . The braking heated the rims and made the glue lose it’s adhesive properties and when high cornering loads were applied, the tire would get pushed right off the rim and some poor dude got a nasty case of road rash.

[@lbx5359]

When using shoes over multiple bikes, I would suggest to be wary of Q factor and pedal spindle length! Especially if the bike types are radically different (such as an all-road and an mtb)

[@cruachan1191]

I got 5 TPU tubes from a certain Chinese marketplace website for the same price as 5 butyl tubes (~£20) and so far had no issues with them. Had one flat, but that was a self-inflicted pinch flat and nothing to do with the tubes.

[@tomkunich9401]

But TPU tubes leak air fast like Latex, and they wear out in the saddle pack.

[@cruachan1191]

@@tomkunich9401 That hasn't been my experience, only had to blow them up at the same rate as butyl tubes, and if they do wear out then that's acceptable if they're the same price as butyl tubes, to me anyway

[@MoaCube]

I always wonder why they never mention those Chinese TPU tubes. BicycleRollingResistance says that something like RideNow is absolutely comparable in performance to the likes of Tubolitos or Pirellis at fraction of the price. And in my experience they hold air as well as butyl tubes.

[@VLuchansky]

@@tomkunich9401 riding TPU for two years straight now and while air leaking might be an issue within certain storage conditions, this has never been a problem while on the road. I also had my spare TPU tube in the saddle pack for like a year when I simply hadn't any punctures, and when I got that needle right in my tire, I just got the tube from the pack and installed it, it was absolutely fine.

[@cruachan1191]

@@MoaCube Alex did mention using some Chinese ones a while back, don't know if it's for a future vid/long term use though. It's the Cyclami ones I've been using.

[@Chris-0703]

I was descending Mt. Diablo on a hot day this summer, and there were a lot of switchbacks and heavy traffic that necessitated dragging the brakes. There was just no way around it. I had alloy rim brake wheels and had fitted 28mm tires even though my frames clearance was only listed at 26mm (I still had about 2mm of clearance and went with it). About halfway down I heard the (seemingly) unmistakeable sound of brake rub. Pulled over, checked the calipers, didn’t see any problems, continued on. About another mile down the road I heard it again and noticed that my front wheel was slowing on its on. Got off and checked again: My tire had expanded to fill that 2mm gap and was rubbing (dragging really) on the top of the frame. I let out some air, took a little break, and made it down to the bottom safely…and immediately changed back to 26mm tires. So, I can’t speak to the math of it all, but the heat buildup made those tubes/tires (TPU tubes if it matters) expand at least 2mm.

[@padmanabhaprasannasimha5385]

I descended Mt. Diablo on a really hot day a couple of months ago on rim brakes and alloy wheels with 28mm clincher tires. It actually might have been one of the hottest days of this year. Had no issues at all. But tbh I'm only a 63-65kg rider who inflates to ~62-64psi front and ~65-67psi on the rear. I also don't descend very fast so I was on my brakes for a good amount of time. I don't know how my new carbon rims would fare but I've done a few descents in the bay area like Page Mill Road and they've held up just fine. I don't continuously ride the brakes but instead brake to scrub speed with both rear and front. Even if I'm behind a car, I usually alternate engaging and releasing front and rear brakes to allow the rims to get some cooling. For every second of braking, I try to give at least a second of cooling.

[@robinseibel7540]

There are quick links that are spec'd to be reused. YBN makes quick links that they say can be reused up to 5 times, and those links are available in at least 11 and 12-speed versions.

[@Tikadok]

I am an overweight rider that wants to ride a road bike. I bought a second hand aluminum bike with hydraulic disc brakes, and changed my tyres to 30c. Anymore tips so that i can have confidence riding my bike? I am easily over the weight limit in all bike manufacturer. All the best! #askgcntech

[@robertlight2370]

The aluminium frame will take your weight without problem - they're really tough. Hydraulic disc brakes will stop you, repeatedly. The only "weak link" might be your wheels. It is possible to get wheels that will cope with heavy weights, after all they make racing wheels for tandem bikes. Those wheels have more spokes to take heavier loads. If you have doubts about your current wheels, visit your local bike shop and discuss it with them.

[@Toastybear1]

Seriously, my weight has fluctuated from 15-19st for my whole cycling career, I’ve taken lightweight carbon bikes down mountain bike trails, ridden converted aluminum time trial bikes on the same, and in cross events (not recommended for clearance reasons) and I also used to ride that aly TT bike at the skate park. Please don’t worry one bit about the bike. There are some high end components or frames that wouldn’t like it, but they’re aimed at the 7kg and under bikes. If you’re still worried, please please go and watch “road bike party” on KZbin, martyn from GMBN showing the world what a road bike can really take! There’s also quite a few “road bike at the bike park” videos :)

[@凸Bebo凸]

Steel frame and 36 spoke wheels are what you should be using if you are over 100kg. There is no need for aluminum because the drag over 100kg of weight is impossible to overcome so you don't need a stiff frameset, shoot for comfort instead. Also you should be using 35mm tires, 100kg is about the max weight limit for a lot of 32mm tires. 32mm tires will run fine over the weight limit, 300 pound riders ride skinny tires, but it's just gonna make you slower because you road contact patch will be too squished, and risk a blowout, there is no point.

[@H457ur]

Way back in the day I was riding a very long downhill at high speed on a very hot (~40°C) day on 21mm tubular tires inflated to 120+ psi, when all of a sudden I had a double blowout. Fortunately, my tires were properly glued onto the rims, and so I didn’t immediately lose control of the bike. I managed to get it down to about 5 km/h before I fell over. I wasn’t even riding the brakes, but the combination of high heat and hard braking was enough to cause an issue. I never again rode tubulars at that pressure on a hot day. In my mind, this is one of the better things about disc brakes - sure you can have brake fade, but you’re not going to have blowouts.

[@jockdoc07]

Good information from Alex, as usual.

[@ThePottingShedWorkshop]

No problems with tyre pressure going up with temperature, yeah, right. Had my tyres a bit hard on the descent of the Joux Plane, a couple of hundred metres before a corner, BANG! Luckily I had enough time to stop before crashing. I had my tyres much softer after that!

[@DetroitJohnny]

Back in the day of 25 mm tires pumped up to 100 psi or more, I had a Vittoria tire pumped up to the maximum pressure listed on the sidewall. The day got hotter, and I didn’t notice the drag on my rear rim brake. Forty miles later, the tube failed suddenly.

[@larryt.atcycleitalia5786]

Amazing. I worked challenging bike tours in the Alps, Dolomites and Pyrenees for 2+ decades with riders of all shapes, sizes and abilities. This was all before disc brakes/carbon wheels. NEVER once did I see or hear about tires or tubes failing due to braking heat. Sure, we'd have clients claim their brakes/rims got too hot so they'd stop and let 'em cool down, but we never saw any failures like you describe.

[@matt_m126]

I already have a home setup that uses grid power and solar. Being in a Northern country, the solar power in winter becomes insufficient, but I also cycle indoors more. Would be nice to generate power/charge my solar batteries from my training as a supplement to using grid power and solar.

[@paulgrimshaw8334]

Re chain links… KMC sells multi-use links. They say they can be reused six times. I’ve always had more trouble re-linking a waxed chain… but never a failed link.

[@Cycle.every.day.]

Never mind all that , the brake wire in thumbnail doesn't have an end crimp cap.

[@Local.hero.1983]

Old school guys used to put a drop of solder,looked tidier

[@0-60.tests.with.Passengers]

The bike was likely built for a video knowing it would be gutted after, groupset had to go back to channel sponsor (Shimano)

[@nishieda]

Tubolito makes TPU with a n ultra thin edition which NOT intended for rim brake users.

[@JanneRasanen2]

This stuck to my mind when TPU first came. Are there durable TPU tubes that work with rim brakes? I live on a hill so every ride risks limb and life on a fragile tube. No Tubolito for me.

[@nishieda]

@JanneRasanen2 there are TWO versions. So I bought the "rim compatible" Tubolito.

[@FullSimDriving]

Great to see Alex moved on from his "synthetic fuel" days and can do efficiency calculations with Watts ❤

[@matt_acton-varian]

I will always replace a quick link then I feel less resistance when it goes back together - and never ride on a weakened one. So always keep a spare to hand when you plan to remove your chain.

[@H457ur]

Josh Poertner over at Silca says that he reuses quick links (he doesn’t, per se, recommend it, but he does claim to reuse them). The thing that he says to do is to keep the quick link with the chain that it was originally on; if you have two chains, then you need a quick link for each. There are also quick link brands that are designed to be reused, for example YBN 12-speed quick links.

[@Chibster83]

#askgcntech I’m hearing what sounds like my chain rubbing on the front derailleur cage when pedaling, a cyclical sound once per revolution. If I stop pedaling for a few seconds, the noise goes away when I resume pedaling, but slowly the noise returns. I’m running an Ultegra 11- speed di2 group set but recently installed a 2x12 speed crankset in order to get 160mm cranks. I have checked multiple times, and the chain is not actually rubbing. What could be causing the noise? I recently installed a new bottom bracket, and that seemed to help for awhile, but the noise has returned.

[@davidkoothottil]

#askgcntech When I fit a new chain to my bike, when I resize the chain to length, if I am careful to not remove the pin all the way, I can connect the chain without a quick link. Is there any performance advantage if I do this? I mean, the chain would be uniform, shouldn't that improve something, like shifting? I get that there is a disadvantage involved when trying to wax and so on, wanted to know if this made a change, if any.

[@justsomedude7556]

I have a couple pairs of shoes with the same pedal system, one for gravel and one for road as the gravel shoes get more nasty, but outside of that, they work great

[@SheriffsSimShack]

For the discussion around 5:00 ofc this needs to be kept in mind. No wants a trainer which shuts down. So if no one is pedaling the power needs to come from the grid. So easy of use needs to be decoupled from the power generation part. So the trainer needs to be first and foremost a trainer. A trainer which also can be plugged into the wall to generate power. Maybe with a second plug. I can imagine that many athletes who train a considerable amount of time preparing for races, or tris are able to crank out 100 - 200 watts for hours on end. thats quite an amount of energy and more than swift,the laptop/pc really needs. Maybe thats not worth it from a financial standpoint, but this is what our planet really needs, and the mindset we need.

[@AlexSalikan]

Exactly what I was thinking. It’s not about saving 30p, it’s about saving the planet

[@Trailchaser-NE]

I was descending Honister Pass doing the Fred Whitton (with rim brakes on Alu rims) a few years ago now, but my front innertube blew instantly and I almost lost it big style. Obviously I crashed but luckily onto the grass at the side. It was quite a few minutes before I could touch the rim because it was so hot, and the innertube was also hot and had a massive hole. Incidentally, while on the side of the road I saw someone else T-Bone a group and they all crashed. I feel a lot happier these days with discs although I have been known to get them to smoke !!

[@Papalazapoo]

Similar thing happened to me on a 25% descent a few years ago. I made the long overdue move to discs after that.

[@brianrichardson5310]

If you are descending from 3700m to sea level then there will be a much more substantial change in tyre pressure due changing atmospheric pressure. Tyre pressure is measured relative to atmospheric pressure. Opposite change by climbing. Descending 1000m should produce a measurable change. Can't be arsed to calculate it :) Same cause (when climbing) as tyres exploding in aeroplane holds.

[@philiphumphrey1548]

The question about increasing tyre pressure with temperature should be calculable using the standard gas laws PV = nRT (if I remember my chemistry correctly). It's probably not exact because the tyre may stretch slightly as pressure increases, and also become more elastic at higher temperatures. So the volume V may change rather than staying constant.

[@kestralrider313]

I can confirm that you can blow off a tire on long steep decents. When I was dropping 6K' decent on aluminum rims, I had a bulge then blowout due to the rim getting so hot that it burned my fingers when I tried to touch it and change my flat. There was also a melting rubber smell. Tire bead expansion was probably part of the issue plus the extra pressure. Never had an issue with the zip carbon and zip cork pads, except that they suck in the rain.

[@larrylem3582]

I imagine lots of people have rim overheating/tire exploding stories. I descended Mt Baldy in Southern California on Specialized Trispokes and when I got to the bottom of the switchbacks, my front tire blew. I think the carbon section insulated the aluminum rim and temperatures went way up. The rims were way too hot to touch.

[@Exciplex]

I used it on the road to inflate my replacement TPU tube and it worked well first. But being home the tyre was flat again, there was a leak on the valve. May this have been caused by the (very cold) CO2 inflator? My TPU manual says to not use CO2 inflators but does not give any rationale... #askgcntech

[@markusseppala6547]

Weird that almost no one talking about chain waxing doesn't know about re-usable quick links like kmc or connex.

[@sebastianschreiber5302]

i just bought a connex link. What drives me off a little is that it is financially unattractive. Its marketed to last one chain live. But I think i could buy 5 original quick links for the price of one connex. its going to be hard to use up 5 quick links over the usage of one chain.

[@markusseppala6547]

@@sebastianschreiber5302 Yeah true, remember to put it the right way on the chain. Being used to quick links I didn't know it mattered and got chain skip.

[@凸Bebo凸]

Always makes me laugh the people bragging about reusing the cheap KMC link on here with the pin retention bushing that only bends once. Hit a bad shift with your link on the cassette one time the chain is flying everywhere, goofy move just get a Connex link or learn how to press a Shimano pin back in if you are cheap.

[@brianrichardson5310]

Must be on my 5th reuse of a shimano 12s quick link. No problems. Can someone explain how these are meant to fail? Such as stomping on the pedals; or suddenly stopping pedalling .

[@paulgoff5068]

The simple answer is Yes, the more complicated answer is that starting at normal ambient temperature tyre pressure will vary by very aproximately 0.1bar for every 10°C change in tyre temp.

[@n22pdf]

I've thought about the trainer and power idea many times and my thinking is your trainer just directs the power you output back into the grid.. if everyone did this including gym clubs etc this would then collaboratively generate a fair amount of power.. we would then all be working as one big team :) Pete

[@RATM1971]

Yeah, except the power we produce is ridiculously minuscule. The trainer, fan, TV, AppleTV is going to take more power than we produce making the idea unsustainable.

[@massimoserafini8115]

#askgcntech hello gentlemen! Question; I’ve been running Continental 5000 with butyl tubes for years and just recently switched to Vittoria cotton tires with TPU tubes. Since it’s a completely different set up do I need to adjust my tire pressure?

[@floridabridges]

15:12 "Love you, bye" 😅😂

[@immortalclass]

Sharp edge on spoke hole can be chamfered with a special hand tool. Rim tape must state Tubeless. I believe Schwalbe for one, specify two full layers of tape, not only one.

[@Flojo-1]

#askgcntech: Hi All: Have I permanently ruined my brand new Shimano 105 chain when I degreased it for the first time? I put it in my ultrasonic bath for too long and with a too concentrated degreaser solution. I thought that the brown material that was coming out of the chain was packing grease but it turned out to be rust being created.... Has my cleaning attempt damaged the Sil-Tec surface treatment or done any other damage? The chain is no longer silver but dark grey...

[@sbccbc7471]

If the rust has penetrated into the side plates too deeply, turning into structural rust, replace it. A chain with such rust severity will snap anytime.

[@Flojo-1]

@@sbccbc7471 I don’t think it is that bad….! It has affected the surface so I wondered whether the chain is ruined as one needs smooth surfaces on the rollers and plates. Plus would the Sil-Tech treatment have been damaged

[@sbccbc7471]

@@Flojo-1 That probably has happened. One of my customers degreased his wife's chain with an excessively aggressive degreaser (not meant for bicycles) after I told him I saw at least seventeen cracked side plates on it. Fortunately, she didn't crash before I found out.

[@JLneonhug]

Hmm probably not worth a video on it but Fwiw, car tyres heat up during faster travel. It'll easily go 4-5c higher when on motorway and around the same delta if its sun or not sun facing while travelling. Psi doesn't go up that high but is in regions of 2-6psi from cold/hot (for normal road use). Volume of tyre within cars are much higher than bikes so I'm not sure if that has any influence on change in psi. Anecdotally, I've not experienced anything different in most conditions so assumed other forces cancel it out. Cf is a good insulator of heat anyway so that probably has the largest bearing.

[@kaiflorianmehrlander4888]

How much does tire pressure change when ascending and descending due to the difference in air pressure because of the altitude difference? #askgcntech

[@HGMMA]

#askgcntech a few years ago I switched from spd-sd road pedals to Spd (mtb) pedals because all my rides start in really heavy traffic (live in Boston), the ease Spd allows to clip on and off in heavy fast traffic seems the best and safest way to go. Traditional road pedals are a nonstarter, do you think double sided speedplay pedals could be as appropriate for this urban environment?

[@jakebrakebill]

#askgcntech I've been riding for 35 years and have tried every cycling short made and the chamois is halfway up my backside rather than under me. Hardly anything is between my sit bones and the seat. How do manufactures find center from one to another so the chamois meets the masses ? On the bright side, I save all my old ones to use when I'm lying on my back changing the oil in my car, there the pad works great.

[@larryt.atcycleitalia5786]

Maybe you're putting 'em on backwards? But seriously I've tried shorts on and found the chamois to be in the wrong place. I notice this in pro races where the pad (like yours) seems halfway up the poor guy's backside. Over the decades Santini shorts/knickers/tights have always had the chamois/pad in the right place for me and my wife. Ever tried 'em?

[@jakebrakebill]

@@larryt.atcycleitalia5786 No, but thanks for the heads up, I'll check them out. Just tried Giro underlayer bibs, made to use with mountain bike shorts. They even have a relief hole in front which is cool, and I've been wearing them without shorts. And almost 95% of the chamois is underneath me.

[@jakebrakebill]

@@larryt.atcycleitalia5786 oh, another thing, how do they run size wise, true to fit ? or run small or large ? thanks

[@회기-c3w]

I had an aluminum rim fail on a 12% downhill due to pressure increase. Typically on steep descents my front rim becomes too hot to touch.

[@MildStallion1]

I believe Kevlar is used for puncture protection in car tires. Has it ever, or is it currently being used in bike tires?

[@sbccbc7471]

Some tires do have a kevlar lining in the construction. Some of them use something similar like aramid.

[@Wiebe_B]

#askgcntech I find it quite difficult to find the correct tire pressure, different online calculators give large differences on advised pressure, for example from the calculator from silica or from SRAM the difference can be 1 bar. Any idea why this is or am I doing something wrong..? Thanks

[@griffithd05]

The big problem with thinking that the amount of power your trainer is showing is the power it is consuming is that the power isn't 1 to 1. If you're _resisting_ the trainer at 300W, the trainer is only using maybe 5% of that power from the wall/mains to achieve that resistance thanks to the gear ratio of the trainer to the flywheel. Never mind all the loss of efficient power transfer from you to the trainer back to the grid or battery or whatever.

[@rayF4rio]

Uncounted punctures? Too many to count? That's what I took from that phrase.

[@matthewrowley1367]

I want to carry TPU tubes as spares. Can you use a CO cartridge to inflate your tire? If not how do you inflate them quickly, say you are in a race.

[@JanneRasanen2]

Theoretically the plastic TPU material can become brittle possibly failing. Maybe tubeless is safer in a race.

[@victoryz90]

#askgcntech Hi Ollie / waxed chain patrol, I'm getting more and more into ultra rides and have also started waxing my chain this year. I was wondering whether you would switch to oil before a 500km ride. Even the new endurance chip by silca doesn't last that long and of course on such rides there is always a chance of a bit of rain or wet roads. Any tips?

[@shayraveh2994]

#askgcntech Hi tech gurus. Just purchased a new bike in raw carbon, clear finish. Is there a product you recommend I should apply on the frame to protect it from UV light, or is the lacquer sufficient?

[@BrentonChan]

#askgcntech Hi Alex and Ollie. Josh talks about layering wax (whether it be Super Secret over Super Secret or Super Secret over Secret Chain Hot Melt) after a ride to get as close as possible to 100% coverage. How should one clean their chain before adding another layer of Super Secret? Is simply running it through a microfibre cloth adequate, or do you need to use a cleaner + cold water rinse beforehand?

[@maniac0303]

TPU tubes are expensive. But it's the most cost effective way to tune your road bike.

[@annetted380]

#askgcntech I have a S-works SL7 and was going downhill at about 80 km/h. This is when the bike started to wobble. I could hardly control the bike anymore and almost crashed. Is this an indication that there is something wrong with my bike? What could be causing such a wobble? #askgcntech

[@AlexSalikan]

That’s called a tank slapper. Something to do with the resonance of a wobble at a certain speed making it amplify itself

[@simonsimon8213]

Try squeezing the top tube with your thighs

[@30nabster]

What you’d want is the power you generate to be used to run the turbo! The turbo actually uses a lot of power applying the resistance. Turbos like the Tacx Neo can run without a power supply.

[@JanneRasanen2]

Wattbike is not the same as a turbo but they work on the power of the rider.

[@markbaker5345]

#askgcntech Hi you guys, I have always kept my bike indoors but will need to store it in a shed. The shed is well built and seems quite water tight but I am worried about damp rusting parts and also heat drying out lubricant and sealant. Is there any bags or storage devices I can put the bike in within the shed that doesn't need me to dismantle/reassemble the bike (ie taking off the handle bars, lower the seat hight) each time I want to store it or use it. thanks!!

[@stephencharles6932]

#askgcntech So tell me about servicing my BB. Is it an annual check and regrease or based on km? Or based on some other weird 'wheel spin/noise algorithm'? I need to get my local shop to do this and it's not cheap so I don't wish to over do it. But then again, I don't wish to have problems down the road...basically, when to service the bottom bracket?

[@sbccbc7471]

Usually it's done annually.

[@凸Bebo凸]

Get an SKF Square Taper bottom bracket blue loctite it into your frame. 160,000km service interval or about 10 years of riding. You don't need to take it out the blue loctite will protect the threads from rust. Using bottom brackets that wear out once a year is a waste of time, the older tech is superior.

[@colinb8327]

Wouldn’t the increase in ambient air temperature as you reach lower altitudes would make more difference?

[@johntheconnor8721]

Hi guys is it possible to make any rim brake wheel tubeless or do i need a specific tubeless wheel? I have a pair of nice carbon rim brake reynolds i was thinking of converting. Thanks in advance #askgcntech

[@cptjeff1]

You need tubeless compatible wheels if you want to be sure it will work. And the GCN crew will tell you you absolutely need a tubeless-ready wheel. The people who pioneered the technology, however, were not using things made for it, since those did not exist. Using non-tubeless specific equipment tubeless can certainly be done! But they were experimenting and risking it not working, and you would be doing the same. With good tubeless rim tape and tight fitting (ideally actually tubeless ready) tires, you have a good shot of success. But it's not guaranteed. What's your tolerance for experimentation and failure?

[@johntheconnor8721]

@@cptjeff1 thanks for the insight, much appreciated. I was seeing lots of things saying you need a tubeless ready tyre which i was fully prepared to use but nobody was talking about the actual wheels. I’m assuming that i can still upgrade my tyres (because i’m struggling to find new high quality tyres that are not tubeless) to tubeless tyres but i’ll still need to run an inner tube to ensure the bead stays seated on my wheel?

[@cptjeff1]

@@johntheconnor8721 I'll put this a little more simply- if you do a good job with your tubeless rim tape it will work tubeless just fine 99% of the time. But unless the manufacturer explicitly says it's okay, the GCN guys will never tell you to do it. They have sponsor relationships and sponsors do not like it when they recommend you do things other than exactly what's in the instructions. If it's not made and labeled for tubeless, there's no guarantee it will work. But that does not mean that it won't work. It almost certainly will. But you're not going to be able to complain to Reynolds if it doesn't.

[@trisportguy64]

I had a friend blow out a carbon rim on a steep descent. He was hard on the brakes when the side blew out.

[@uralmutlu4320]

Power harnessing isnt so straight forward. Your output would never be linear so you'd need an opportunistic charging system, a bit similar to solar power charging. You are absolutely right that it would be bulky.

[@kiekendiefkiekendief1668]

#askgcntech I recently swapped my racing tyres for new winter tyres for added puncture protection and wet grip. I opted for pirellis Cinturato 28mm with reflective stripes. They were 10 euros more expensive than non reflective versions but I think they look absolutely smashing on my Trek Emonda. I was wondering why those stripes are almost non existent on tyres from other brands, the extra sideways visibility really makes riding in the dusk or dark much safer and they don’t look that much different on a bike then a pale skinwall tyre. Why is this not the default option?

[@jolde3000]

There are tires with Black reflective strips too

[@mikechang2023]

Black Mirror episode from season 1!

[@fransenfiets]

Quick Links ALWAYS get re-used😂 YEARSSS, my friends

[@paulgrimshaw8334]

Forget braking. A bigger issue wrt tire inflation is accounting for pressure change when a bike is stored indoors, inflated indoors, and then used outdoors in the early spring and late autumn… ~21C -> 5C. It’s the same thing in reverse in the summer… ~21C -> 35C, but road temperature can be in the mid 40s.

[@kevinfeeney5309]

There's a video of Robert Forstemann powering a toaster... posted maybe 10 years ago.

[@TweexcoreUnderground]

#askgcntech when going up climbs above 6%, if I'm in the saddle and in a low gear/high cadence, sometimes my front wheel will lift off the ground. I haven't crashed yet, but I'd rather not. Is this a bike set up issue or a problem with my technique?

[@brianrichardson5310]

That shouldn't be happening at 6%. Maybe at 16%. Can be due to setup and technique, but at 6% there's probably a setup issue - your weight is too far back. Could be your saddle is too far back, and that could be if your bike is too small for you. Technique wise, move forward on the saddle when climbing. Normally, this is for comfort and efficiency, not wheel lift. The other possibility is you are putting out massive power!! But better pedalling technique may help, don't use the legs like pistons but try to maintain a more constant force throughout as much of the rotation of the crank as possible. This is more likely a low cadence thing, though. Perhaps at high cadence you're generating lots of torque. Shouldn't be an issue, though. BTW are you using a lay back seat post?

[@TweexcoreUnderground]

@@brianrichardson5310 just using a regular seat post, bike is the the size they fit for me at the shop (not a full bike fit, just a quick one). Seems to only happen if I'm already in the small right at the bottom of the climb (if I've had to stop at traffic lights for example). Shall try shifting my weight forward more and see if that resolves it, otherwise I suppose I might need a full bike fit. Thanks for the detailed response!

[@newhorizons.english]

#askgcntech I have a pair of cycling shoes that's a size larger than normal shoes that I'd ordinarily use. My question is should I always go with the number I'd use when buying walking shoes?... I've heard in the past people recommending getting a cycling shoes that are a number larger... Cheers guys.

[@RATM1971]

People greatly overestimate the power they are generating indoors. Busting out your nasty 200w for an hour will be just enough to power your trainer, AppleTV and monitor, but probably not your fan. We already generate power from bikes, they are called dynamos and usually generate just enough power to run a light, or maybe charge a phone, but not both at the same time.

[@maciejkrasienko8164]

#askgcntech what's up with the naming convention of bikes? Why are the lower numbered variants the higher spec and not the other way around?

[@johnstrac]

Riding Continental GP 5000's and it would break my heart to only get 2,500 miles out of them.

[@Ryan.T89]

They’re a racing tyre so they’re obviously going to wear out quick.

[@johnstrac]

@@Ryan.T89 Gotcha, that'll do it then.

[@凸Bebo凸]

I can't ride those the soft rubber rips apart on Los Angeles streets within 6 months of use.

[@JanneRasanen2]

​@@Ryan.T89Actually they are a training/robust racing tire. Unlike true air balloon single race only tires 5000s last thanks to the puncture protection belt. As long as you don't hit glass, sharp stones and thorns. They kill everything but some of the toughest touring tires like Schwalbe Marathon plus.

[@mikesmith2864]

#askgcntech I'm a 75 year old life-long cyclist, coming off an almost ten year hiatus due to health issues. With an FTP in the low one hundreds, does Zwift offer anything for me? Can it help me get back on the track bike, or is there a minimum level of fitness to even use the app?

[@DeeKayDoubleUSee]

#askgcntech Hey Alex & Ollie, I would like to ask if there is any way to keep my matte grey painted frame and forks free from scratches, stone chips, scuff marks road grime and the likes of it? Many thanks!

[@sbccbc7471]

Paint protection film. An automotive detailing studio may be able to help with this if they're willing to. I've handled one that's been wrapped by the studio he owns to test the idea out.

[@Toastybear1]

300w for an hour (obviously) is 300w/h, or 0.3kw. You ride for a couple of hours at 300w, you’ll make half a kilowatt. So about half a unit, at current prices about 10-30p worth of electric. That seems like not very much, but it would be £73 a year if you did 2 hours a day

[@g.fortin3228]

Really should have pointed out that you do not need to buy the expensive TPU tubes because the more budget ones have been proven to be very good as well.. at 1/3 the cost of the pricey ones.. carry a spare LoL

[@joetreleaven5462]

What a crazy question..? What...? How do they think of this stuff..?

[@Music-pq8cm]

I don’t ride on terrain that would require the amount of braking that would cause an increase in rim temperature. I’d venture to suggest that 95% of all cyclists don’t ride on terrain that would require the amount of braking that would cause an increase in rim temperature. Now yes, perhaps a timid unskilled rider descending a mountain road would ride their brakes as they descend (I’ve ridden with some of them). But one might suggest that the timid unskilled rider should ride only on terrain matched to their skill level and level of emotional comfort? Just a thought hmm

[@Gixer750pilot]

An answer to questions asked in 2006. 😂 brake discs just left the room. 🎤

[@gcntech]

Little by little, we’re catching up 😃

[@Doktor_Al]

I swear if I hear another #GCNtech presenter say, ‘how long is a piece of string?’ I will switch to GTN.

[@AlexSalikan]

I think I just barely heard Conor pronounce my name right 💪

[@OriginalTrev]

maybe Conor can't but Sally can

[@TESTA-CC]

More heat the better, will only increase the pressure in the tyres due to thermal expansion.

[@chrisspeksnijder1717]

Its the ideal gass law. PxV=nRT. Basic elementary physics gents.

[@st2en]

Wippermann chain links are perpetually reusable.

[@CsatiZoli272]

Generate electricity with an indoor trainer? Robert Förstemann demonstrated that it's possible: kzbin.info/www/bejne/iWWyZqmlhKikd7M

[@TESTA-CC]

Don't use the Silca calculator, if your running carbon wheels, you will end up blowing out your carbon rims because of the wrong pressures advised, I would stop at 95psi on every carbon rim, it's more than enough pressure.

[@tn9274]

at Taiwan Taoyuan airport, there is static bike that setup to generate electrical power for passenger to have fun with. I tried probably only 15minutes and not sure how many useable power it generated.

[@mikedellar5653]

If Connor is happy to get only 2500 miles out of a GP500, he clearly has very low expectations - and very deep pockets.

[@gregknipe8772]

hot pavement is more of a factor.

[@JackMott]

"Should I consider non race tires?" NO!! .\/.

[@larryt.atcycleitalia5786]

Uh, where were you jokers back when carbon tubeless/rim brake failures were very obvious? I remember video of one of those "sandbox classic" early season races where they neutralized a descent for some reason and you could hear "pop" after "pop" as tires exploded off the rims. Can't say if tires or rims failed but racers were stopped waiting for new wheels, all caused by what could only be braking heat.

[@mathewrose2951]

If you absolutely, positively do NOT want to have to change your rim tape in your lifetime (or even your great-great-great-grandchildren's lifetimes), you can get Velox tape from France for about 6-7 euros. Woven with kevlar and it has more sticking power than that one night at Uni your mates still would let you forget.

[@cheec8548]

The topic really makes me stress.. I think ppl are running out of questions.

[@johngammon2471]

TPU in an aluminum rim, with rim brakes, WILL IMPART EXTREME Heat in downhill runs, likely to result in a blowout. #askgcntech