Why are my different power meters reading different numbers? How do you calculate watt savings? How should I store my bike? All these question and more are answered in this edition of the GCN Tech Clinic!
00:00 Intro
00:27 Why do different power meters read different number?
01:57 Can I calculate watt savings myself?
03:55 Do I upgrade to a carbon fork or new wheels?
05:32 How should I store my bike?
07:41 Is my power meter under or over reading?
08:39 Can I use my tubeless tyres with tubes?
09:20 Can hydraulic brake fluid freeze?
10:15 Is wet lube any good?
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Welcome to the gcn tech Clinic where we aim to answer your bike Tech and maintenance related questions as ever you can submit your questions Down Below in the comments section using the hash sgcn Tech and we’ll do our best to answer as many of them as possible
Within the a lot of time and before Alex’s laptop takes off cuz it’s the fan is is going for it that’s how tricky the questions are this week right um David heathfield 504 says I’ve always found that crank SL pedal based power meters uh read slightly higher than Hub and turbo train
Parameters I thought this was due to the power losses through the system leading to lower readings the further down the chain you go my power meters still read a good 10 to 20 wats higher at the pedal um and crank then attacks Neo um I’m not sure I entirely agree with this because
I feel like the people that making T brands that making turbo trainers they’ve accounted for all this they’re not all of a sudden oh damn we forgot to account for the drive train L short no no no no no you like it’s me where you measure the power does affect the
Reading okay so like you can actually in theory measure if you had like a power tap Hub yeah and you had a pedal based power meter okay if they were both accurate you the differ the difference would be your drivetrain loss okay yeah I can get on board with that however
That seems like quite a lot of drivetrain loss that he losing there which suggests that this power meter might not be totally accurate I’m always more inclined to believe the you know like a wahoo kicker or ATT attack Neo as being more they’re generally more accurate so yeah while you should be a
Bit lower there than you out at the pedal I think maybe your pedal base power meter is over reading a little bit but who knows okay um I’ll read this next question out because it’s aimed specifically for you all right quite often when you’re talking about marginal
Gains you brackets Ole this means you will run through some math on what x wats means over y time and Zed elevation is there a calculator out there that can let one play with the whatif games like this um ideally one that can analyze your existing data say on this ride
Putting out five Watts more or saving five Watts on a new tire um what time would you get does this kind of ccul exists yeah yeah so these kind like there’s various different systems out there that you can go on most of them um most of the good ones aren’t free but
Nothing in life is free is it yeah but like there are various things so you can use things like golden cheetah um and also like my favorite one is my windstock which you I’ve mentioned in videos before go on there and you can play with various uh values what makes
My wind sock much more easy to use though is when you do actually have some good data on consistent set courses so it’s only as good as what you feed into it you know you I think that’s a good point like it’s just you don’t really want to analyze your Sunday ride cuz
There’s just so many unaccountable unaccounted for variables like the traffic is totally different the where how much you spend your time drafting behind your mates that kind of stuff it’s it’s very hard to like analyze things like that against each other but for time trialing great yeah um and if
You’ve got wind tunnel offer analyzing your performance on climbs really good and if you’ve got some actual aerot testing data that’s more quantifiable so you know your CDA so from things like um wind tunnels or track testing that people offer those Services they can measure it for you that makes your
Calculations even more accurate when you start playing around or different option just going to throw out there head out into the real world and do your own experiments by physically testing it yourself rather that’s what you do yeah but you don’t have to you can just do it
And monitor your own results like in the most basic way yeah but these tools just allow you to quantify it and measure it and record it better I’m with you on that okay um right next question says I have an entry level gravel bite with a suspension Fork without a lockout I want
To upgrade it to make it faster especially uphill which option do you recommend a a decent budget or friendly carbon fiber fork or for the same price a new set of wheels thanks in advance love the show shall I go first and what I think I would do I
Would get rid of the basic suspension fork and I would get a decent budget rigid fork and then that way I think you’ve got the right basis and core of what you need if you’re bothered about comfort you can tun and refine that with your tire choices and then I would
Gradually evolve it and look at changing the wheels what do you think about using like an upgrade Fork that is suspension but has a lockout like yeah you use some good like sun T yeah that is an option I I’m trying to think how I would
Want to say this so truth the in my heart I want to say I don’t necessarily feel like a suspension what belongs on a gravel bike but because I think you can tune it and refine it enough through careful choice of tires and tire pressures if you feel like you’ve
Maximized what scope you have available with the tire pressures and the choice of tires and stuff like that and you still want more I think that’s the reason what you should then start to look at a suspension for a gravel bike but at that point you’re also not a far
Off mountain bike territory yeah um so I would I wouldn’t jump to having a suspension fork and a grab a bike I’d go rigid Fork save a bit of weight and tweak it with your ti choices yeah I think that’s probably the best way of going about it cool uh next question is
From em or EMA 06 who says hi team I recently got a new temporary job which means I’ll be driving to work instead of cycling so my commuter is going to go unused for once two years it’s a long temporary job uh how is best to prepare
The bike for long-term storage is it worth doing any maintenance while it’s being on used to protect the components I was thinking of doing a deep clean lubing the chain then leaving it untouched until I need it again it’ll be stored in a dedicated bike shed in my
Garden in the UK I’ve got 105 mechanical and the components currently have plenty of life in them many thanks I feel like they’ve kind of half answered their own question here cuz I’m inclined to pretty much agree with what they’ve said they might do and like thoroughly clean everything most important thing is
Drying everything properly because if you leave moisture it’s just going to cause corrosion and then like lubricate and protect any components which are exposed to the air because if you leave raw metal out it’s going to eventually corrode yeah I think another thing as well is you know we don’t know your
Specific shad but I uh just getting a sheet and covering it in a sheet is going to be good because it’ll keep dust off it and cobwebs and stuff and um the other reason why that can be beneficial is it it’s actually blocking the light from
Hitting certain parts of it um UV can damage certain areas so we know from you know doing a video on this and the shelf life of carbon that that’s not really a problem for carbon um it’s paint’s unlikely three the biggest area I’d be concerned about would be
Like other polymers on the bike so uh things like your your shifter hoods your B tape and your tires in particular you know tires crack with UV so yeah just making sure that it’s covered in a sheet block out most the the UV from uh from from getting to it and damaging those
Bits and really quick random story I used to leave my bike it always angled one way in the conservatory um when I was a kid grown at my parents house and only after ages and ages it eventually dawned on me that the paint on one side
Was really faded and the other side was really bright cuz it was in the light Alex that is a cool story it is I’m glad you appreciated it and right next question uh Jerry McBride says I got an FTP drop of 15% using asoma Duo um or
The tax neo2 compared to my original 4 I um crank power meter Ling the power meter questions right so that is I think he that is a a comment we had a couple of weeks ago yeah where people were it might have been Jerry McBride where he
Was saying about his thinks his power meter was under reading yeah cuz his four and we were like no we think your four eyes over reading yeah I think that’s most likely the situation isn’t it yeah like we mentioned we literally just mentioned it typically an indoor
Trainer is going to be a bit more accurate than a on bike pal me a lot of P meters aren’t like you know it’s quite common thing that people think their FTP is 400 yeah and it’s a sad day when you find out that it’s not yeah unless you
Find out it’s 500 yeah and and Danny jbr 8870 next says hi guys I recently bought a bike that came with tubless tires they pelli chiner AOS and they seem perfect winter are there any safety pitfalls if I use them with inner tubes they didn’t
Seem they didn’t seem to pop on the rims when I inflated them even though they were deemed compatible with my wheels wondering if it’s due to lack of sealant any help would be appreciate it and well this actually pretty simple answer to this there is no safety Pitfall by
Simply putting an inner tube inside a tubless tire that’s on a tubless ready wheel rim no pitfalls whatsoever you’re just simply not getting the advantages of a tu setup or the hustle depends which way around you want look at it next question is from uh jogger the director who says hi olly and
Grunt I think that’s you what oh how these shots fired morning I was going to ride my mountain bike with hydraulic disc brakes but the fluid was frozen so the bike was rendered useless is this a common winter problem when it’s close to minus 10° do I need a winter specific
Brake fluid thanks in advance Cheerio based on what you just called me don’t know don’t care yourself I think proba we like break fluid so mineral oil and like dot fluid which it depends on what type of system you have you haven’t said it there um it it shouldn’t freeze atus 10
Um so the likelihood is that your brake line has been contaminated and has got water in it and that’s what’s Frozen uh so you need to bleed your brakes and um then it should work and it should be okay uh and the last question this week is from f p
Julia who says you’ve talked a lot about who who dry Lubes are and the advantages of wax what do you think about wet Lube with proper care it’s it’s a reliable alternative even in dry conditions well we’re open a can of worms here right I’ve actually filmed two videos recently doing Mega
Deep dives into chains and lubricants and efficiencies with Adam from zero fiction s so subscribe to gcn tech make sure you don’t miss out those in the coming weeks but um I’m going to throw out there that a good quality like wet Lube is and can be like a good
Alternative that’s what I want to say it doesn’t mean it’s going to be as good good it’s probably going to need more care and maintenance and it isn’t going to be quite as efficient which means your chain is maybe going to wear slightly faster but I think is the right
One is a suitable alternative yeah not all wet Lubes are equal you know you can see the independent testing data on it you the things like there’s um like we use Silka synergetic but there’s also one that gets talked about a lot is the diamond black yeah um Rex which is
Really good a lot of other wet lubs are total garbage and will prematurely wear your your chain a lot but I agree wet Lubes can be like the good wet Lubes of which there aren’t many that can be really really good and there’s definitely an advantage to using those
Um for certain people so if you live in like a really wet place so like right now in the UK I’ve got a bik garage it’s horrible it’s January it’s raining all the time there salt on the roads all the time so I’m washing my bike all the time
You know after like every ride I need to rinse it down because the salt and you know that’s then washing the wax off cuz the wax comes off with water and so rather than having to then reapply wax all the time with the drip on which you
Would do like you have to do that the day before you intend to ride because it has to like the water-based carrier has to evaporate it’s so much more practical and easy to just apply a drip on wet Lube where so in those situations like yeah absolutely but um if you want
Maximum performance and it’s not much more it’s just a little bit more um wax is the way to go and if you’re riding in Dry Clean conditions wax absolutely the way to go there we go um that was it for this week’s Tech clining as always apologies if we didn’t get to your
Question but be persistent keep putting in the comments section down below we’ll pick it out and we’ll get to it in the coming weeks love you bye see you this thing’s gonna take off now
42 Comments
Let us know your tech questions using #askgcntech ⚙
Hi Alex, I’m glad you are finally covering some of the ZFC data. Looking forward to it. I love Adam’s work, but I hope you can edit it down to something concise.
@TimR123 how did you miss the chance to land the "watt if" pun at 2:03 😬😬😬
Are the Elite bottles staying in the background until Camelback finally delivers its first shipment of GCN bottles?
Have you really got to pay £1 per millilitre for a decent wet lube? Also aren't the ones you mentioned both wax based lubes? I do use a cheaper one, but clean it off and reapply regularly, but mainly using wax now apart from winter bikes.
I recently had a similar problem with my power pedals and found instructions how to test them by strapping weights to them on the Garmin support website. Would make an interesting video.
#askgcntech
Nerdy tire question:
We've come a long, long way from the era of "narrow and hard = fast", but with more variables like rider weight, tire width, rim width, TPI, tread, tubeless or not, and riding surface to name a few off the top of my head…do we have a good handle on what is optimal? For example, something as seemingly simple and straightforward as "tire width" is actually a wide smear of values depending on a number of factors. I think there are some tables and even maybe some calculators that will tell you the "optimal" pressure for various tire widths, but do those ignore huge reams of relevant variables?
Say you take a 40 mm tire and you mount it on at 23 mm rim at 50 psi and sat on it as a 165 lbs rider on a paved surface. Would it even still measure 40 mm if you took some calipers to it? Probably not. Same tire on 28mm rims would likely measure different at the same psi and/or with a heavier/lighter rider.
Is there anywhere we can go to get this type of information? Thanks, nerds!
Frozen Brake Fluid? NOT! Love the mechanical disk setup on my road bike.
Waxing a chain is not about performance for me. I just like the cleanliness 😁
prob didn't wax their chain
can we test olive oil as a brake fluid?
only in Italian bikes obviously.
#askgcntech I just bought a second hand bike with the maker's actual signature on the frame, done with a permanent marker . How do I not clean this off? Francesco Moser if it makes a difference.
#askgcntech I am firmly on team waxed chain. Generally, I've been good at taking care of it, but the other day I just forgot to clean it after riding in the wet, and it was a little rusty the next day. I did a rinse with Silca's chain degreaser, and rewaxed to get it back, but is this the best method?
Hi, GCN Tech Crew. My road bike has an 11/34 cassette; my indoor trainer has an 11/28 cassette. When I ride my bike outdoors, shifting is very smooth and works well. However, when I put my bike on the trainer, the shifting is very clunky and sometimes skips. I’ve tried adjusting the derailleur, but can’t seem to quite get everything aligned. The research I’ve done suggests I should be able to just put my bike on the trainer and ride, but that doesn’t seem to be the case. Any suggestions? Should I just get an 11/34 cassette for my trainer? Thanks! #AskGCNTech
#askgcntech
Hi guys, how can i keep my white cycling socks white? After a few washes they all tend to get abit darker.
#ask gcn I recently bought a (tri/tt) bike that came with Zipp wheels and I'm considering changing them out with ENVE wheels. What do you think the advantages of doing this, or should I just run the Zipp wheels and just upgrade the tires?
I do race in triathlons/ Ironman and road competitions.
I have a Canyon Grizl Suspension with the same fork replacement issue, the main problem is the suspension forks are 1 1/4 sized instead of the usual 1 1/8 so it won't fit any rigid forks, does anyone have any ideas of a gravel rigid fork that would fit?
Some of the questions you get are so stupid. I'd like to know which hand I should use to wipe my arse
#askgcntech – Back when I used to run an oiled chain and mechanical groupset, I used to just spray my derailleurs with spray oil and wipe off the excess but now I'm on Dura Ace Di2 with a waxed chain, is there anything on the Di2 derailleurs that needs some oil or are they designed to run dry? Thanks!!!
Turbo trainers vs power meters: all the TTs and PMs I've seen recently have similar specifications : +/-1 to +/-2%. Yet you claim TTs to be much more accurate. Are you disputing the manufacturer's accuracy claims of PMs? Shimano PMs are well known to be shite. All other PMs and TTs I have tried have been well in agreement. To those people with accuracy issues, i say this: you must let your PM acclimatise to the temperature at which it will be ridden, then calibrate it. You must warm up your TT with a representative power effort for 10 mins or so and then calibrate it, before trying to take meaningful measurements. These things are highly temperature sensitive.
I have often wondered why GCN promotes Silca and GMBN promotes Peatys Lubes. But which is best? Surely they do the same job. Is it just the ad / sponsorship contract?
Regarding power meter accuracy. No one suggested putting the meters through the manufacturers recommended zero/calibration procedure. I know many have such a thing. I'd assume not all do, but why not try? My old Wahoo Kickr required periodic spin downs to recalibrate, why not pedal power meters?
Frozen brakes; might be time to take the callipers off and give everything a clean
Hey gents , I disagree with Alex’s comment regarding tubeless tires being fine for inner tubes. Schwalbe pro one TLEs are specifically designed to be set up as tubeless and if you put an inner tube in (as I had to recently) they bulge in all the wrong places like a fat lad (me) in an aero jersey! While it is a solution to get you home I would steer clear of tubeless designed tires if you are always going to run a tube. For starters the non tubeless ready tires are normally cheaper!
Love the show
what about a REDSHIFT ShockStop Suspension Stem for the Gravel bike Alex ??
Living in wet Portland, Oregon I tried using wax on my winter bike and went back to wet lube. The other drawback I found is when you are putting on drip on wax a lot you end up with a lot of the wax gunk everywhere which is as bad or worse to clean than the grease. Wax is great on a fair-weather bike, but for my winter commuter I'm sticking with wet.
Grunt hehe
Great video brother!! I absolutely love rim brake. I love riding my Tarmac SL6 but it’s disc, kind of wish I had the simplicity of rim brakes. Been eyeing a Ritchey Road Logic 🤔
#askgcntech Hello everyone, what is the deal with quick-links? For my 12s Sram Rival groupset it costs $18 to get a single-use quick-link (which is outrageous!). Can quick-links be used multiple time (despite manufacturers stating otherwise), what is the risk of doing so, and are there any workarounds to an OEM quick-link. Thanks for your help and love the show!
"cover your stored bike with a sheet"… great idea, assuming you mean a cloth sheet and not a plastic sheet or tarp, as these would trap moisture.
Diggin it. Well done
Regarding the frozen disk brake problem: it might actually the callipers that are frozen. If they are wet for longer, e.g. from rain or melted snow/road splash, water may creep between brake housing and calliper. Once you get some decent frost they might just freeze. Had this countless times. Give the callipers a good clean and dry everything out and they are good.
#askgcntech My indoor trainer (JetBlack Volt V2) seems to give a higher power reading than the pedals (Favero Assioma Uno) on my outdoor bike. For example the difference in my FTP between the two can be as much as 30w. Why do you think this is and which is the more accurate reading?
On storing a bike, as Andrew and Ollie were chatting I remembered that Si had done a video about storing a bike over winter. I did a quick search and it was 8 years ago!
At last an admittance that wax is pretty pointless in the UK if you race and want performance do it the other 99.9% in the UK may as well use oil/lube
Even keeping my Emonda in the garage I cover after every ride with a motorbike cover. The Piaggio scooter can look after itself and worth far less! Recommend motorcycle cover for a velo….
#askgcntech Hi GCN team, I followed the advice of waxing my chain and have been taking extra care after each ride, cleaning it with a microfibre cloth and applying drip-on wax regularly every 200-300km. However, I've recently noticed signs of rust on the chain's surface. Is this normal? I assumed the wax would prevent rust. If not, could you provide advice on maintaining a waxed chain properly?
The online tool Omni Calculator is free and has been developed by PhD students. It is accurate for predicting power against speed/weight and you can select different road surfaces, aerodynamics, tyres and then convert to calories burned. I find it to be within 3% OF Garmin's calculations of calories. I use the formulae shown in Omni Calculator for my spreadsheets.
Joggen; Something else is going on with your brakes.
I ride regularly at -20F, and have never had the slightest issue with the hydraulic brakes from the cold. Not Sram, and I think not Shimano on my prior winter bike.
#askgcntech is there a reason certain free hubs are silent? I recently bought a Canyon Grail CF SL and the free hub is totally silent.. I was expecting the really loud click from high performance bikes. Maybe that's just road bikes.
#askgcntech After cutting some patches from an old TPU tube, what type or brand of glue works best to affix these patches to a leaky TPU tube assuming it is different than the glue used to patch butyl tubes?
Did Ollie say he washes the dirt and wax off after every ride? 🙂