Weight Weenies

I have not yet seen any real weights on the new Rotor Power meter posted so, since I have a pair in my hands waiting to go on a new Cervelo R5, thought I would do so myself

Bare cranks, 175mm, compact 110 BCD - 565 g:


Batteries - 21 g:


Rotor chainring bolts - 12 g:


11 mm spacer needed for BBright:


Praxis 52-36 compact rings - 157 g:


Full ensemble of cranks and rings - 761 g:


Same ensemble measured on Ultimate scales (5 g precision) - 760 g:


Is it good for Weight Weenie power measurement? Rotor claims that it is the "market’s lightest real power measurement product". However, Fairwheel measured the THM M3 SRM at 671 g with 53/39 Praxis rings, so neglecting the 11 mm spacer about 80 g lighter than my Rotor with 52-36 Praxis compact - http://fairwheelbikes.com/cycling-blog/?attachment_id=2906. Obviously the Rotor is substantially cheaper. (I suspect that the Cannondale SI Hollowgram SRM would be similarly light as the M3 SRM.)

I (SRM user) installed one today. Although installation is not much different from a normal 3D crank, I must say, I'm impressed!

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110bcd Hollowgram SRM spider is 121 grams, standard 110bcd hollowgram spider is 40g, so the SRM adds 81g to the weight of a standard set of Hollowgram SiSl cranks.

Please post a picture of the crank when you have the chainrings fitted?

I'm dying to see what the MAS spider looks like with something other than Rotor aero rings.
Thanks!

If my memory serves, that's about 110g heavier than my 172.5 BB30 specialized quarq setup with 110bcd 36/52 praxis rings, which added ~90g over the stock crankset. SRM is supposed to be lighter (~10g?), and I think the Cannondale SiSL is a bit lighter as well.

Thanks for posting

You can save a bit, 4g. I swap Rotor with KCNC chainring bolts (7.6g on my scale).

redhed18 wrote:Please post a picture of the crank when you have the chainrings fitted?

I'm dying to see what the MAS spider looks like with something other than Rotor aero rings.
Thanks!

Here you go:



Would look better without the missing chunk in the MAS spider, but seems they had to make that for the ANT+ communication.

Also note the chainring bolt on the left. On the 130BCD version this is nicely exposed. However on this 110BCD version it is half hidden by the power unit. Inserting and tightening the chainring bolt was a right PITA! I just about managed to squeeze a ball head 5 mm allen key through the gap, and tightened with the 6 mm bolt the other side.

roselend wrote:I (SRM user) installed one today. Although installation is not much different from a normal 3D crank, I must say, I'm impressed!

I also have been on SRMs for a few years, an old rock-solid PC5 SRM Pro. At the moment Wattage list feedback on the data from the Rotor Power has been mixed, so will be interested to see what mine produces.

When is the R5 getting built?

Next week Everything has now arrived and I will finally have some time. This is way behind schedule, but then so is the arrival of spring.

622 grams (but hard to find)

Comparison unfair since that one is with Fiberlight chainrings. But definitely other Quarq options are lighter, for example S-Works (138 gram spider) or Cannondale versions, and this SRM is 698 grams.

Rotor gives you both sides, however. I'd like that since I have some physical assymetry (fitter gave me footbeds to help with that). But it won't help with pacing.

djconnel wrote:... this SRM is 698 grams.

The THM M3 SRM was in fact my original plan, but the mixed BCD for the compact version makes chainring choice limited and with the Rotor just out thought I'd give it a try instead.

Rotor power meter with Praxis rings actually looks quite good. Looking forward to mine arriving

On an italian forum some guys (4) are complaining about some issue; it seems the powermeter would happen to read 0 for long sections during the rides.

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micky wrote:On an italian forum some guys (4) are complaining about some issue; it seems the powermeter would happen to read 0 for long sections during the rides.

Maybe they were coasting. They should try pedaling.