Shimano Power Meter (R9200P): How is it this bad?

[@Hydrogen101]

DCR being critical of the most powerful corporations in the sports industry makes him the most trusted (and feared) name in the business.

[@toadlguy]

Most people in the industry care about what he says, because he is trustworthy. Shimano, not so much.

[@Timtimzi]

He even called out strava’s BS. That’s the type of honesty I like to see… unlike other cycling magazine news outlets that skim the surface

[@CycoWarriorx]

He’s gonna need a 12-member security team… 😬

[@future62]

No, him being objective, good or bad, is why he's so respected. Defining credibility by ones affinity to smack talk "big bike" is how you get cults around quality individuals like Durian Rider.

[@AK-je7ns]

Unbelievable in this day for a company like Shimano to have this on the market. Thanks for holding them to account.

[@kpizzle1985]

The problem is this is pretty much standard for Shimano

[@cvn6555]

Important executives get fired over these types of huge mistakes.

@@kpizzle1985 no its not… sorry

[@kpizzle1985]

@ my dead Di2 battery, crumbling rear caliper, destroyed R9100 chainset and #thanksshimano disagree

[@MrT_RainMan]

@@cvn6555 Yes, in a good business that should happen. Fully agree. Thing is Shimano knows they build low quality products and the mass market just keeps buying.

[@martinh6028]

Finally, the right power meter for me. I'll take the extra 20W.

[@toadlguy]

But you lose it all when you go for the sprint.

[@Stevenafoe]

@@toadlguy no way, just stop pedaling and there’s more free watts.

[@bredemeijer9648]

They have the left as well

[@danielrobertson3071]

Good to see honest reviews like this

[@Timtimzi]

Love the critical review. He even called out strava’s BS. That’s the type of honesty I like to see… unlike other cycling magazine news outlets that skim the surface

[@D4D22]

Looking forward to the GCN video extolling the virtues of the new Shimano power meter 😂. Thanks for the ballsy, well researched video!

[@Yocambio]

Thanks for pointing me in the direction of the Favero Assioma power meters, which I purchased and have been enjoying thoroughly!

[@James-KL]

Once again, your detailed analysis provides excellent information for us cyclists DC! 👏

[@nationsnumber1chump]

I don't always over estimate my FTP or win the Zwift race, but when I do...

[@TheITNerd]

It floors me that a company the size of Shimano can put out a product that is this bad.... TWICE. This video convinced me to buy the Garmin Rally pedals instead for my new SL7 that I am getting shortly. Thanks DC!

[@iMadrid11]

The problem is either the company culture. Or Shimano is hiring incompetent engineers. Even if you are a highly competent engineer. If the company management is not on your side. You won't be able to execute to deliver a good product. You won't be able to make design revision changes to fix hardware and software bugs. You won't be able to fix factory production errors and improve efficiencies.

[@benjorito76]

It´s not without irony...not wanting bad, overpriced products while ordering a SL7 😉

[@saracen888]

I hate to break it to you but the Garmin Rally’s are not great

[@WeirdFishStick]

You might wanna swap that crankset for something more durable too..

[@nowave7]

@@iMadrid11 The engineers may be incompetent in making a reliable product. They are, however, not responsible for putting it on the market! ;)

[@williamstevenson2649]

Great work. I'm a long term Shimano user, and have been happy with the kit for decades. I don't have a power meter, but have been vaguely thinking about getting one. Before this review, I would have assumed that the official Shimano PM would be good but expensive. Clearly, this thinking was mistaken - as much of a shock as the chocolate bonded Ultegra cranksets that break

[@michaelmastell6778]

This is really interesting. I was watching a podcast the other day where they were discussing Tom Pidcock’s power from a recent stage and they mentioned that the power data was in question. Now it makes sense.

[@Marty72]

I think power meters are one of the few products that gets honest reviews on the KZbin

[@Dcrainmaker]

It helps that it’s so heavily data based, yet, it’s also key people show all the data and that they know what to look for and what to test for (eg both chainrings, easy pedaling, etc…).

[@revolveramd]

R9200P is superb for zwifting: you stop pedaling, and watts stay high

[@benjorito76]

By what I see almost everyday on Zwift, a lot of people must use these R9200P...while weighting 45 kg or so.

[@andreasjsn]

@@benjorito76 🤣

[@JeffBudden]

Sticky watts 😂

[@mabozza85]

Strava and Shimano now have a combined bounty on your head DC!! Stay safe😘😘😘😘

[@rcuadro]

So outside use the large and on Zwift use the small. Thanks Shimano!

[@robertreinhardt4924]

Frightening! Do we know if the Giant power meter is made by Shimano? Does it suffer the same issues? The hardware does look different. Not much info out there about Giant power meters, specifically on the latest 8100 groupsets. Stellar work as always, DC!

[@trroland1248]

That was going to be my question exactly.

[@vicgregory7596]

Giant is made by Stages

[@germurphy4986]

Considering how many instances of Shimano DA & Ultegra cranksets falling apart, and now their ability to have fully functional PM, it goes to show how they respect their customers. The price of high end bikes and groupsets means these items should be 100% all the time.

[@shepshape2585]

For those looking for a very accurate power meter at a reasonable price, go get yourself the Favero Assioma Uno or Duo. I've had the Uno for a few years now and I love it. Super accurate, and I love being able to simply swap the pedals onto one of my other bikes if I want to swap my power meter between bikes. All sorts of reviews on these, including from DC where I believe he chooses them as his top choice.

[@supersixmikeohimod]

in an N+1 world, I don't see why anyone would run anything other than Assiomas or pedal power meter.

[@ronskayakingandfishing414]

100% agree. I bought a pair in 2020 based on his reviews/advice, have not regretted it one iota.

[@Boomeranger]

I have the Faveros on three bikes. Dead nuts accurate and easy to deal with.

[@8paolo96]

Me too, bought them a couple years ago, never had a fault, a disconnection, or anything to really care or think about them except the random battery recharge. Really really fantastic

[@AndiKoF]

It's so sad they have no spd version available.

[@robb1267]

Strava: we are a dumpster fire. Shimano: hold my beer.

[@christophmuller830]

Thanks for your test! I bought the new DuraAce R9200-P Powermeter about a year ago because I wanted an accurate system 🙁 I thought Shimano must have learnt from its mistakes from the first generation and now brought a reliable system onto the market. Besides, Shimano, especially DuraAce, stands for the highest quality for me. And now it's totally inaccurate and you can't rely on it. Hopefully they will solve the problems via firmware update!

[@RyonBeachner]

I got Garmin Rally Pedals when it came time to upgrade groupset because I saw that Shimano hadn’t gone to a symmetrical crank arm type setup after the very lengthy explanation of it causing accuracy issues with crank based power meters. I was prepared to buy a 9200P and a new set of Dura Ace pedals, however instead I just got the standard crank, and a set of Garmin pedals. If a product manager at Shimano is reading these comments, yes, consumers do make decisions based on this type stuff.

[@kestralrider313]

thanks for revealing this and providing such a long and thorough analysis period and an enormous data set. It's hard to believe that Shimano would like something this flawed to go out under their flagship label. I'm deeply in the SRAM camp for other reasons, but I'll be sure to stay clear of any Shimano PMs for the near future no matter how good the price. I suspect that my 10+yo Powertap wheelset would outperform these cranks in accuracy.

[@karstenmeinders4844]

I have recently noticed on Canyon's website that the top spec Speedmax models (TT/tri bike) come with Rotor cranksets and powermeters. I have thought this might be due to supply chain problems. Now I know better...

[@daniels.2720]

"Supply chain" problems alright = ie: nobody wants them >> haha

[@MartinOrtega-kt5bw]

Every day I feel happier and more justified in my decision to buy Favero Assioma pedals. Not only are they one of the cheapest options, but they're also one of the most accurate. I've even gone a couple trips where I got a rental bike, and I just brought my pedals with me and boom, power data on a rental bike!

[@shawnsmith7009]

The acquisition of Pioneers power meter business seems like a great investment.

[@PowerRanger83]

Big yikes.. and to pick up on the last part of the video. I am also looking into a new bike with the new Shimano 12s Ultegra group set. More and more bike integrators ship those with the Ultegra FC-R8100-P powermeter. Since the Dura Ace one is no good, I don't expect the Ultegra being any better. I'd rather save the 750 to 850 bucks and get a better wheel set for example. I myself am using the Favero Assioma Duos, partly because of your postive review. Super happy with those pedals.

[@stigfalck8179]

Looking forward to your review on the firmware Ver. 4.2.0 update to the FC-R9200-P. The performance/accuracy looks better, but a review with testing would be appreciated.

[@Nebulacore98]

Great review of the Pedals with Data to back it up. I've always had issues with my Shimano 105 Mechanical Groupsets (5800 & R7000) working with Ultegra FD or FSA crankset. Over 10 bike shops later, still had issues. Switched over to SRAM and no issues. So not unexpected of Shimano. I'll never go back to Shimano for road bike parts. They're Mountain Bike components however are great! Glad I'm using Wahoo Speedplay Powerlink Zero Dual-Sided Powermeter Pedals now too!

[@PawlNguyen]

Are you having to extra "cover yourself" stating multiple sources, multiple times because it's Shimano? Youre awesome, dude!

[@davebishop2566]

Welding Chrome alloy is probably a more difficult process then welding Ti. Most likely the welding procedure used in Taiwan didn’t include inert gas purging like with welding Ti. Without internally purging with argon the glowing red hot metal inside is exposed to air oxygen and is oxidized and as it cools it builds a sweat from moisture condensation. After these frames are welded the Tig weld need to be normalized by reheating and annealing. Now it’s been heated twice. Next the frame was probably bead blasted then sprayed or dipped in phosphate solution to clean exterior oxidation for powder coating. The frame gets heated in a oven with 50 frames hanging on a rack. After the phosphate is dried the powder is sprayed on and run back into the oven for 30 minutes. From a manufacturing standpoint most frames are welded in a purge fixture. The fixture holds the bottom bracket and head tube and rear triangle solid enough machine finishing faced surfaces isn’t required. Some frames go through a tweaking fixture as a worst case. Those holes in the frame are used as vent holes so that when the powder coat is cured in the oven air pressure can escape through the holes and not a pinhole in a weld. My point again is that “Steel”, chrome alloy has the same problems as Titanium but it’s not economically feasible to to do the purge. With Ti welding without inert purging is impossible. The frame looks great. Not as cool as my Yeti frames but SUPERNICE. That bottom bracket looked sweet. Keep banging

[@florianbusch94]

Now a comparison to SRAM Red Axs Powermeter would be interesting to see!

[@jsprhrmsn]

There is no hiding here for Shimano as it's pure facts/data who's doing the talking. Great video!

[@christophmuller830]

Hi, did you notice, Shimano just released a firmware update for DuraAce Di2 group set and R9200-P Power Meter to connect both via ANT+ to combine the watt value with the used chain ring for more accuracy. Maybe you can recheck it again?

[@dk4366]

Ive got the ultegra cranks and im defiantly not seeing the same issues. Power is pretty much exactly the same as what my tacx 2t shows and rides outdoors show 0W at the same times as 0 cadence. Happy with my purchase.

[@AndyKaylieno1]

I swore off Shimano after the Hamnerhead thing even after never owning anything but Shimano equipped bikes. Thank you for confirming my decision. Shimano seemingly hates it's customers, it loves its customers'money for sure, but it seemingly goes out of its way to show its hatred . Now I'm trying to figure out if this has always been true and I was too blinded by marketing to notice or it's a newish thing.

[@sanjaynayyar]

I guess my desire for Stages to release a 12speed Ultegra level power meter is even higher now.............

[@sebrooks1]

Great review, and absolutely appreciated as a cautionary statement! Also, I want the shark-riding-a-bicycle t-shirt! :D

[@inakilrg]

We trust you. It’s just crap.

[@niekversteege]

I am not really surprised. I remember years ago GPLlama did a video on how Shimano crank based power meters are likely inaccurate.

[@toddgilman9476]

Thanks for the data. I'm in the market for a pedal or crank power meter and this data helps. Question a little off topic, but I love your shark bike shirt. I'm relatively new to Triathlons (only 3 olys under my belt so far) and absolutely love the sport. Can you point me towards where you found it?

[@johnroper7776]

Interesting video. I have bought and been using the Favero assioma duo-shi power meters following your review and can only say that they seem to work for me, although I don't go into the stats in any depth relying on the summary provided on Garmin Connect as I am using the 1030 plus head unit.

[@Christensoncardioclub]

Crazy, the DA power crank is like $800 more than the non-power cranks, can’t believe they’re continuing to sell it.

[@davidburgess741]

Still riding a 1979 Campy power meter crankset. It's called perceived exertion. As an added bonus it doesn't split down the middle and cause crashes. With crap like this, Shimano still makes some good lower end components..... in Taiwan and Malaysia!

[@DoNuT_1985]

Wow, imagine you get a fancy new bike including Dura-Ace and then you're actually better off with your 1-sided Assioma pedal or the good, old strap-on Garmin cadence sensor proudly sold since the early 2010s.

[@rhysbeth]

So glad Canyon supplied my Endurace with a Rotor power crank set and not the planned Dura Ace model.

[@PeakTorque]

Assioma, 4iiii left arm, or Quarq. End of story! Great video.

[@maxgrass8134]

Always very high quality content! An now I know which Powermeter not to buy!

[@evertidema3338]

‪Great video. Was there any response from Shimano on you analysis?‬

[@mlegrand]

They've had time now. Bad results were 'kinda' understandable when it first came out. They are aware of the issue right?

[@Dcrainmaker]

Yes. For many months.

[@aitorbleda8267]

They are selling, so no issue I guess...

[@kennibal666]

Clicked the like before video started playing. :D

[@Dcrainmaker]

That's the spirit!

[@Bendersnatchling]

I knew it! My other half disagrees, but OBVIOUSLY I have to buy a THM Clavicula with an SRM. Thanks

[@morosis82]

Looks like it's doing some sort of smoothing. I wonder whether the problem with it dropping made them try to smooth the readings to compensate, so the soft pedalling trips it up because it thinks it's dropped.

[@timhall7771]

I figured it must be bad, given the delays since it was announced, but this is quite special! Now that this one is out in the open, any chance of an updated power meter buyers guide?

[@bonn1771]

Thanks for doing this Ray. Saved me some money

[@mghallock]

Just brutal. How do they make the same mistake twice? I had a 9100P and it was so far off from every other power meter I had (Garmin Rally, Quarq, even Stages Shimano which share some of the same issues with L&R power balance) the 9100P would just radically under-report on power, no matter how many times it was calibrated and the power would drift with larger temperature changes. SRAM's gaining ground not because their shifting or ergonomics are superior, but because Shimano can't seem to get its power meters right, whereas Quarq is bulletproof and available at every level (Rival, Force, RED).

[@HugoB32]

Thanks for the great video. Do you reckon the problem might be worse/better depending on the size of the small ring? Or completely unrelated?

[@GlennRacing1]

Great review. Would it be a given that the same issues would also occur on the Ultegra version ??

[@mfu424]

Great video! Did you have any experience with the SRAM Rival AXS Quark Powermeter?? Did you hear of similar problems there? Thanks for your work!!

[@chriskennedy1076]

Sad day in sports tech imho. Just hoping stages can figure it out for an aftermarket solution and can make a reliable right side pm.

[@8584zender]

we had a team deal with shimano and several teammates had di2 groupsets with the Shimano PM. nothing but problems. ive had almost every brand of PM on various bikes over the years with great experience. Quark is still my fave.

[@ianbales]

Is the plot at 6:00 mislabeled? It shows the shimano power meter (green) indicating 0 power when not pedaling, which seems accurate...

[@drhspies]

Has this problem been solved yet? I unfortunately bought the power meter just before I saw this video!

[@Dcrainmaker]

Sadly, nope. The firmware update last winter meant to solve it…frankly made it questionably worse.

[@obikedog]

Love Shimano but oh man so glad Favero saved me from that mistake! This is for sure an outlier for any company but especially Shimano which is known for rock solid reliability where others fail.

[@shawnfedun8431]

What can you do with your DA power meter. Mine came on the bike and it has a right/left inaccuracy that is quite large. Says my right is lower than my left by about 30-50 Watts. This doesn't happen on any other power meter I used. Shimano says that their power meter is accurate to +/- 2%. This is obviously not the case so shouldn't they be responsible to either fix it, replace it or reimburse it? Seems like false claims!

[@ulrikmortensen9426]

Just buy Favero Assioma Duo. They are super accurate and ALWAYS work.

[@jsliepen]

I find it astonishing as Shimano bought Pioneer, how made really solid power meters according to you. They have the solution at hand wouldn’t you say?

[@andrewcockburn7484]

I came here to say this. My pioneer is still going strong. How did they mess up so badly?

[@WowRixter]

I almost bought one. So glad I bought another set of Assiona Duos. Thanks Ray 😁

[@againthebegin]

9100 and 11-s ultegra shift just fine with otherwise 12-s Shimano drivetrain. Running a dual-sided stages on mine now, works great. Single-side stages would too. Doesn’t solve the problem of getting stuck with paying for this on certain bikes though.

[@jwlarocque]

Except for the small chainring issue these problems all seem related to the polling rate. I wouldn't be surprised if they could mitigate (or even solve) the issues by increasing it, at the cost of battery life. Of course if that's the case it should be fixable with a simple firmware update; I have no explanation for why Shimano wouldn't provide it.

[@keithmcgarvey8273]

Hey DC Rainmaker! Did this power meter ever improve since your review? Many thanks!

[@Dcrainmaker]

Sadly not.

[@keithmcgarvey8273]

Thank you for your reply sir! Keep up the good work! 👏🏻I read your review on the 4iiii 3+ Pro Dura Ace and ended up getting a brand spanking new one for $1000.

[@GilbertTang]

Does the same issue happen on the Ultegra version? I’m assuming it’s effectively the same. Edit: It is indeed basically the same.

[@Canadian666]

Let’s see how long it takes for Shimano sending out solicitor letter

[@drigobarreto]

Out of topic: Did you noticed that Garmin finally merged training status over devices? Today I found no status by device and other new details. Appreciate if you could talk about it.

[@Dcrainmaker]

Yup! More detailed load/video later in the week. Lots of nuances!

[@SimonLerpiniere]

Not updated for me. Still split by device (UK)

[@drigobarreto]

@@SimonLerpiniere try search for firmware and app updates. Device and phone.

[@SimonLerpiniere]

@@drigobarreto Nope. All up to date, and still same.

[@beppohilfiker9388]

great to have "official" confirmation on this long time suspicion. thank you! but what are the alternatives if: you already have a shimano crank; you want a dual sided PM and don't like the pedals because of the stack height and/or q-factor? is 4iiii 3rd gen now reliable on the right side as well, or is 2dn gen 4iiii the only accurate dual solution?

[@ImpactWench]

I also have Shimano cranks... in little plastic bins, labeled up to perhaps put on eBay. The bikes have Rotor cranks with one spider and one spindle power meter.

[@MatthiasStevens]

Is it safe to assume the FC-R8100-P (Ultegra version of the unit reviewed here) is plagued by the same issues?

[@adhithyasodhi3203]

All these corporations work for us - no sales, no business. Stratospheric pricing & crap engineering? Unforgivable

[@mebeasensei]

This is good news. If they are crap at measuring power, I can punk my restricted e-bike by swapping out rear sprockets and still hope I have a 50/50 chance I can break the lousy speed restriction

[@kaushikiyer3859]

And almost the entire Peleton is on Shimano. 😅. The power of money and being a market bully! Anyways I’m glad I’m in Campy camp and Garmin for electronics 😊 Kudos to DC for being honest and not afraid of such a big corporation possibly going after him.

[@chris1275cc]

WOW That's bad. I have a couple of cheap Chinese (X-Cadey) PM's on my Gravel bike and winter bike, The Gravel one (GXP spider based on older FORCE arms) is pretty accurate but its not very consistent (spikes and drops a lot) that's fine because on gravel I only want a ballpark figure. The one on the winter road bike (105 NDS only) is inaccurate (reads high) but its pretty consistent so its easy to "work with". But A PM that is both incinerate and inconsistent is just useless weight. SHIMANO is fast becoming Japanese for "Shat the bed"

[@catalin5186]

Hi .. did you use that specific unit on your bike .. to me it looks brand new ... No paint scuffes ??

[@cyclemadkiwi]

wow, that's a shocker! Well you could try revisit the IQ2 pedal power meters! lol.......apparently they're shipping now, I'm still waiting though for mine......Love my vector 3's

[@chris1275cc]

They aren't shipping to backers (like me and you) though, they are selling them with 48 hr turnaround to anyone who wants one 🤣. I have to laugh about it at this point, because buying a baseball bat and a flight to the Netherlands isn't a sensible option, although I hear their prisons are pretty cushy.

[@simonvonbromley5948]

Great work, Ray 👏

[@andrewmcalister3462]

Shimano having accuracy issues with their 1st generation power meter is not great, but you understand it can happen. Having it occur on their 2nd generation PM is appalling.

[@007StarKiller]

I have a 16 watts difference at 200 watts and even bigger when producing more power between my Wahoo Kickr Core and dual sided Favero Assioma. How can I tell which one it's correct since i don't have a third power meter to compare them. I would like to know if there are some sings that one it's reading wright or wrong. Great job by the way.

Thanks for bringing this up… since the 9100 disaster i never have been thinking to buy a shimano powermeter, which is also expensive, but i have to say that third party os not easy to find and mostly you have to replace the whole cranks … or use a pedal based. I use Garmin and Power2max for now

[@sandrogamperle2989]

I had one on order with my new bike but just called the shop to cancel the order for the power meter. Will add power meter pedals or the Stages power meter later on and order the Shimano Dura Ace without power meter. Thanks for the advice/warning!

[@superstrada6847]

Firmware update please! If the Shimano power meter was examined by other power meter companies and determined that it's not the cranks themselves then won't a software/firmware update at least modify the problems?? Help!

[@GoofballVidProductions]

Trek seems wise to the issues, as they offer their Shimano equipped top bikes, PM-free. No such issue with SRAM, as any top SRAM equipped Trek comes with a PM included. Absolute disaster for Shimano. My Madone is the Shimano version, and the Assiomas are my go-to PM.

[@maxgrass8134]

Thanks a lot for this! There is a also the Ultegra R8100 powermeter. Does it use the same technology and is it also affected? Many thanks!

[@Dcrainmaker]

Same tech.

[@tommyrq180]

This is all work Shimano engineers could be and should be doing. In my view this is similar to the Shimano E-TUBE app, which is abysmal. It could be so functional but it’s horrible. Have loved Shimano gear for decades but something is wrong.

[@OTBTBDA]

Question: Is it the belief the data reported at the crank arm or pedal should be the same at the rear axle, if the data is inaccurate? It is impossible for the rate of torque at the rear wheel to match the rate of torque at the crank arm or pedal.

[@andrewwolf4430]

How are you testing this unit. Example you would need a calibrated unit to test against. I didn’t see that in this video

[@bradleytipp2750]

I went Stages (from Shane's recommendation) because of this. Stages managed to make this work dual sided...

[@Second247]

I'd love to know if they actually did or did Shane, and Stages, get just lucky. Because the problem should lie in how the driveside crank is constructed, it's hardware issue. Watched one detailed video on it describing that it will remain inherentily inaccurate as long as the crank remains as Shimano has designed it. Basically they can try to compensate it somewhat with software with-in the crank, then it works for some people but for others it will remain inconsistent. So maybe the new software fits Shane's profile as cyclist? While for others it will remain inaccurate.

[@gplama]

Stages changed the gauge placement on the right side.

[@Dcrainmaker]

I've got the Stages LR unit on there now. So far so good...more to come in the following weeks. In talking to Stages, this was the most complex crank they've had to design a PM for, but they believe they've nailed it. And given the ringer that Shane put that unit through, I'd agree they've probably done so. Thus far, my testing is looking positive.

[@palicar]

Kind of shopping for a power meter. Might just put road power pedals on the gravel bike. Too many options but not the right one…

[@trannel73]

Always love it, when Shimano makes it so easy to laugh at. First cables for their electronic group set (in the new versions, where SRAM already doing an awesome job with wireless technology). And now this power data misery. :D :D Keep it up. I’m well amused. Thank you, Shimano ❤️

[@mikicastan]

Cables are plus mate and one battery is big plus comparing to sram. Not to mention shifting action 12a shimano groupsets that is unbeatable on the market

[@jamble7k]

when is sram gonna make a reliable front derailleur

[@trannel73]

Just messing with shimano people. Sorry for my statement. With 1500km on the bike per year I’m not supposed to have such a sarcastic opinion about manufacturers 😅

[@AdamAlgeroth]

Great material. Share it to friends!

[@dylanl9532]

Except for the sprint power underestimation, it seems pretty good for "zwift". Feels like sticky watts.

[@WorstSanta]

Isn’t it actually 4iiii? It’s infamous for its problems.

[@joelberman5981]

When will you review the Nix Biosensors?