Rotor Announces INspider Power Meter for Shimano Cranks

Dec 20, 2023
by Jessie-May Morgan  
photo

Rotor Bike is introducing a Shimano-compatible version of its popular INspider Power Meter, designed to work with SLX, XT and XTR cranksets. The Spanish brand claims their INspider power meters are the only spider-based power meters that are able to measure power accurately for both round, and oval chainrings. That's thanks to the high torque sampling rate of 120 times per second - so, if you're pedaling at 60 rpm, the INspider takes a measurement 120 times per revolution of the cranks. Other spider-based power meters with a much lower sampling rate tend to give erroneous power measurements thanks to the inconsistent curvature of the chainring.

photo

Rotor INspider Power Meter for Shimano Cranks - Tech Details
This is Rotor's very first spider-based power meter that is compatible with non-Rotor cranks, bringing the technology to those who run a Shimano crankset. Spec-wise, the new Shimano-compatible INspider is much the same as the Rotor one, only the OCP Mount spline replaced by the Shimano's Direct Mount spline, and the profile adjusted for chainline requirements.

It adds a 99 gram weight penalty to your drivetrain, in exchange for power, cadence, estimated balance and torque information that can be transmitted directly to your cycle computer of choice via ANT+ or Bluetooth Smart. The 100 x 4 BCD INspider is compatible with round chainrings from 30T to 36T, as well as ROTOR's own Q-Rings (that are oval in shape).

As the oval ring varies the effective chainring size throughout the pedal stroke, it allows riders to clock the largest part of the chainring to match up with the most powerful portion of their pedal stroke, maximizing use of it while smoothing out power delivery to the rear wheel. The Q-Rings can be mounted in a variety of positions, and the best position is said to vary between riders, likely dependent on how their anatomy is pre-conditioned to deliver power, lever lengths, crank length, seat tube angle, saddle position, and I'm sure a heap of other factors. The Rotor INspider power meter can also be used as a tool to dial in the correct Q-Ring angle, by virtue of its Optimum Chainring Angle feature.

The INspider measures power from the right and left leg combined, with claimed accuracy at +/- 1.5% over a temperature range of -20ºC and 50ºC. Its lithium-ion battery is rechargeable via USB, and has a claimed run time of 350 hours on a full charge.

photo
The Rotor INspider is machined from 7075-T6 aluminum. It is rated to IP67

Pricing & Availability
The Rotor INspider Shimano-Compatible power meter is available now at an introductory price of 449 €. More details available on rotorbike.com.

Posted In:
Reviews and Tech First Looks Cranks Rotor Inspider


Author Info:
jessiemaymorgan avatar

Member since Oct 26, 2023
52 articles
Report
Must Read This Week
Police Called to Scott Sports Headquarters as CEO Dispute Continues
63819 views
First Ride: Fox Releases New Grip X & Grip X2 Dampers
45989 views
Pinkbike Poll: Center Lock or 6-Bolt Brake Rotor Mounting?
42317 views
Tech Briefing: Fancy Suspension, Carbon Wheels, Spring Apparel & More
37082 views
Pinkbike's DH Fantasy League: Get Your Team On The Line for Round 1
33262 views
SRAM Patent Shows Compact Motor x Battery Unit
31375 views
Bike Check: Craig Evans' Airdrop Edit V5
30389 views
First Look: Fair Bicycle's Drop Best Offset Saddle Clamp is Universally Compatible
29080 views

49 Comments
  • 74 0
 Why did Mr Ohm marry Mrs Ohm? Because he couldn't resistor
  • 2 0
 Now that's some quality electro humor. It's positively shocking...
  • 48 1
 Pair of jump leads walk into a bar
Barman says ‘ ok you can have a drink , but I don’t want you starting anything ‘
  • 8 0
 I kept reading batman and couldn’t get the joke Big Grin
  • 35 0
 People asked me how it feels when you stick your finger in an electrical outlet? To be honest, it Hertz.
  • 7 0
 So you'd say it Amps you up?
  • 12 0
 hey pinkbike, y'all should do a power meter shootout. I would be curious among the different styles the pros and cons.
  • 3 0
 Thats more of a GP Lama and DC Rainmaker thing.
  • 7 2
 To preface, I run a PM on my enduro rig as well as my short travel bike. Two years ago there wasn’t a good option for a mtn bike power meter other than Quarq XX1 for well over $1200 for the cranks and power meter assembly (Stages really wasn’t great, not to mention a lack of chainstay clearance on most frames). Now there seems to be a lot more options, P2M is very good (not all that cheap but cheaper than Quarq) and most recently it seems Sigeyi has good options for even less ($380). Have had Quarq XX1 for over a year (very good but does force you to do their whole system, including carbon cranks which I’m not big on) and now have a Sigeyi Axo for Shimano cranks on the way. Rotor may be a bit late on this one, don’t know what took all the manufacturers so long to widen their compatibility but glad to see it now!
  • 1 0
 I run pedals for my gravel, but glad I don't for mtb as I blew up a pedal this year on a tree stump. I JUST got a 4iiii for my enduro rig last month and this comes out.... but you're correct, it only fits my bike because it runs 55mm chain line spacing cranks but I'm glad there's options now in the future.
  • 1 0
 I have the Sigeyi and Xcadey ($300) spider-based PMs and both have been faultless for 2 seasons.
  • 1 0
 My XC bike has a 4iiii. I technically still have a Race Face spindle power meter in my enduro bike, but it quit working years ago. But I don't do intervals on that bike anymore, so I don't care. Stages on my gravel bike, and Vector pedals on my road bike.
  • 1 0
 @NoahColorado: Never heard of those brands before, how is their weather resistance? Do they seem pretty accurate?
  • 1 0
 The roadie in me might show, always had PM's on MTB, I don't get dudes who drops $$$ on suspension and then don't really have a true understanding about gearing, cadence and pacing.

@NoahColorado both Sigeyi and Xcadey are well established now, accuracy is good from what I heard. (I don't love the stages that I have (random power spikes and some drop off issue))
  • 3 0
 Why is it that power meters are so expensive in general? I realize prices have come down with more options out there but I'm genuinely not familiar with the technology. So why for instance is a HR monitor or cadence sensor $20-$30 but power meters are hundreds or thousands of $$?
  • 7 0
 HRMs have been around a long time in a variety of sports and industries (i.e., health care, occupational safety). The implementation of an HRM is largely the same no matter the context. In other words, a chest strap is a chest strap no matter what you’re doing. It’s the same for an optical sensor with the added bonus that you’re even more flexible with where it can be worn.

Power meters, specifically strain gauges calibrated to convert strain of bending metal ever so slightly to power in the context of cycling, are incredibly niche. To add to that, the implementation of the strain gauge and its calibration will differ slightly if you’re measuring at the hub vs crank arm vs spider vs pedals.
  • 2 0
 @pmhobson: Thanks. From that description it would seem there's a possibility for alot of ill calibrated power meters? Is that a known issue in the industry or does everyone accept folks output numbers? I ask because I have "friends" that will never believe someone has more power output than they do, if so, it's just "not calibrated properly" will be the comment.
  • 4 0
 @yupstate: Shimano has completely shit the bed with their Dura Ace power meters. Universally regarded as horrible.

So no, you can't trust them all.
  • 1 0
 @yupstate: oh you also asked about cadence sensors. Two types:

1) reed switches triggered by magnets. Incredibly simple, cheap hardware, same concept as old school wheel-based speedometers. Used in countless applications to count rotations of things (think manufacturing).

2) accelerometers— fancier tech, but they’ve proliferated even further with smart phones, wearables, etc.
  • 1 0
 Why do people think $500 is expensive for powered cranks but are fine with >$400 cassettes or simple cranks. As an early adopter to PM's (on all my bikes) I don't understand people starting with other upgrades.
  • 1 0
 @mmiloou: you can’t ride a (geared) bike without a cassette.

You don’t have to get the $400, but depending on other specs on your bike, it might be difficult to avoid.
  • 2 1
 @mmiloou: I'd agree with @pmhobson on this. It's definitely more of a niche market for individuals that care enough to know their power output. And admittedly I just didn't understand what makes the power meter so expensive compared to things my brain thought might be similar like HR monitors and cadence sensors, etc. For cassettes there are super cheap ones out there. The ones I consider expensive are lighter and the assumed cost comes from expensive raw materials. Now if there was a $100 steel power meter I could stick to the back of my crankset I'd be all for that. And if the expensive power meter was made of titanium and carbon I wouldn't have questioned it.
  • 2 0
 I've found that for gravity-based riding (enduro, DH, etc.) heart rate is actually a better metric for the amount of stress you're putting on your body.

I do have a power meter on my XC bike, because that is more pedaling. When I had the power meter on my enduro bike, I would often get a stress score from the power meter that was half of what the heart rate monitor said.
  • 1 0
 @yonderboy: same observation here. But I also don't use power for pacing anything except actual workouts. I use RPE only for racing, power is just a fun metric to look at after the event, and that goes for road riding too. I just did 100+ mile gran fondo, and the power was useless.
  • 1 0
 @JSTootell: If I had to do whatever a 100+ mile gran fondo is I would imagine my power averaging 400w, then 300w, then 200w then as I pass the 10 mile mark maybe 100w and then 0w followed by nap time.
  • 2 0
 @yupstate: not really. Unless you are going to solo the whole thing, you just stick with a group of like minded people and share the work. You can do a massive amount of miles on the road when you're chilling with friends and going at each other's pace.

You'd do much better than you think.
  • 3 0
 @JSTootell: Power meters are for everything leading up to the event. As a masters racer being able to track training load is invaluable. Didn't have PM;s as a younger racer (except $6000 SRM's) and I would invariably crater around July from too much training/racing. Power Meters have kept me from doing that.
  • 2 0
 Why go with asymmetric spider.
  • 19 0
 to get to the other side? I dunno, tell me
  • 7 0
 @browner: a bit of asymmetry makes spiders more attractive IMHO
  • 9 0
 Because an octopodal spider might eight you alive?
  • 2 0
 He threatens to sting you if you don't
  • 2 0
 Because their existing rings are that pattern I’d guess?
  • 4 1
 No E-Bike version?
  • 1 3
 Rotor has advertised so much pseudo science in the past - now this also makes me skeptical.

Power is force x distance x time. How can you build a power meter that behaves differently based on ring shape? Are they saying regular power meters are all wrong because sample rate is too low? Exactly how wrong can they be since they don’t know how riders power is applied.

that claim that it ‘works with non round rings’ reads like fake ‘interesting ad copy’?
  • 2 0
 Doesn’t the distance change with an oval ring?
  • 1 0
 Im fuzzy on the details but actually remember reading that inaccurate power readings were actually the reason people thought elliptical rings increased your power output in the first place. If I remember right, testing with a wheel-based power meter showed a different result. It makes sense that a lower sample rate might be the culprit. Now whether these are
  • 1 0
 @hllclmbr: the feet apply the force and their path isn’t changed. It’s the force around the circle that changes with ring shape.

If power meters results change with ring shape then they’d also change depending on how one pedals, example: when standing or pedaling circles.
  • 1 0
 @captaingrumpy:

4iiii.zendesk.com/hc/en-us/articles/360038484072-Using-an-Oval-Chainring-with-4iiii-Powermeters

Not an engineer, but here's a link to a power meter company saying their power meters over-estimate with oval rings and explaining why.
  • 5 0
 Not to be picky but Power is Force x distance/time.

The reason why sampling rate might matter is the speed (distance/time) of a round ring is constant, where as an oval ring is not.

I have a good luck with the durability of Rotor power meters in the past. If I was still into training with power meters I would get one of these.
  • 1 0
 @kclw: doh!
@beeeefkirky: thanks for that link.

Still doesn’t pass my sniff test but I’ll accept it.
  • 1 0
 @captaingrumpy

Ok. In that case, doesn’t the speed change?

*Something* has to change in the power equation.
  • 1 0
 @hllclmbr: speed and torque would change but will offset, higher torque at lower rotational speed = lower torque at higher rotational speed therefor power would be equivalent.....gets complicated with human body and pedaling cadences and averaging over an entire circled when you are really only pedaling at full force when pedals are (approximately) between say 1:00 and 5:00...there may be some efficiencies with oval rings, but it's not much.
  • 1 0
 Regardless of what anyone says, I have noticed no discrepancies between my bikes with and without oval rings. I have oval on two bikes with power, and not oval on two bikes with power, and if there is a difference than I can't feel it during my workouts.

4iiii, Stages, and Garmin pedals swapped between two bikes (one oval, one round).
  • 1 0
 @beeeefkirky: This is true.
  • 1 0
 These look like ever-so slightly rebranded XCadey Power-S power meters. I have to wonder if that's really all they are.
  • 1 0
 A nice price compared to a similar competitor like power2max
  • 4 0
 But these ones require a double calibration on the start of every ride and don't have an auto zero. P2M auto zero's after 3 secs of coasting. If they could actually fix that for the price it would be a very good deal.
  • 2 0
 @dick-pound: ouch, didn't notice that! I really like my p2max! its hassle free.







Copyright © 2000 - 2024. Pinkbike.com. All rights reserved.
dv65 0.040793
Mobile Version of Website