Rotor 3D Crank with Q-Rings

[jdtate101]

As I'm doing the Marmotte next yr and I run a standard 53/39, I was in the market for a compact crankset to make life easier in the mountains. I decided to have a look at the Q-Rings and Rotor 3D cranks. For those who are not familiar with Rotor, they are a Spanish outfit specialising in oval chainrings, but also have a good line in cranks and accessories.
I got a pair of 3D cranks as they come with a 24mm axel and I can swap them for my Dura-Ace hollowtech cranks without changing the BB, which is a major plus. Also got a pair of 50/34 rings, which the diameter increases out to 52 and 36 at the greatest point (about 4 o'clock on each downstroke).
The theory is that they help reduce fatigue, increase power delivery and aid in faster recovery.

1st impressions....well I must say I'm very impressed!!! They shift just beautifully smooth, which was a concern given their oval profile, but I have no complaints. In fact I'd say they shift BETTER than my DA set. They do feel smoother to pedal as there is a noticeable reduction in the dead spot (at 11-1 positions). One side effect I noticed is that they cause you to use your hamstrings a lot more than usual, so therefore feel a little odd to start with, but overall are very comfortable.
The 3D cranks are super stiff, easily the equal of the DA cranks and the fit and finish are excellent. I've only done one real outing on them so far (55miles) but I really liking them so far. In fact I would go as far as to say that I'm giving serious thought to getting a full set of standard rings to replace my DA (sell that) with one of these:

http://www.power2max.de/power2max.php?lang=en

Anyway here's what they look like:

 

[Cycleops]

Elliptical chainwheels have been around since the late 1890's so it's interesting that manufacurers are still coming out with them. Shimano tried it in the late eighties but chose to drop it for whatever reason. I have one on my Dawes and to be honest I can't tell much difference. It's interesting to read your review though.

 

[jdtate101]

I've looked at some pictures of the shimano biopace stuff and it's very similar. I did notice that shimano chose to put the point of greatest diameter at roughly 2 o'clock in the stroke, whereas rotor do it at 4, It's a subtle difference, but probably feels quite different.

 

[Mr Haematocrit]

I have a set of Q-Rings however I run them with carbon cranks, I find the shifting to be OK in general but can't say I'm convinced regarding the claims, a more extreme elliptical shape such as that used by osymetric may be more noticable .
I do find however that they seriously mess up the data from power meters yet rotor have just released their own, I would be interested to know how they have addressed this.

Here is a image of my q-ring setp

 

[Rob3rt]

I have a set of Q-Rings however I run them with carbon cranks, I find the shifting to be OK in general but can't say I'm convinced regarding the claims, a more extreme elliptical shape such as that used by osymetric may be more noticable .
I do find however that they seriously mess up the data from power meters yet rotor have just released their own, I would be interested to know how they have addressed this.

Here is a image of my q-ring setp

View attachment 16578

The Rotor PM is an odd looking beast!

The standard Rotor chainrings look flimsy, bendy rings plus the extreme shape is bound to play havok with shifting. I would buy the TT rings! The added stiffness should improve shifting. Adds a bit of weight but lets be honest, if you are going to pay a weight penalty, as close to the BB is the best place to do it. Most of the pros run the TT rings on their Rotor cranks on the road bikes.

 

[Mr Haematocrit]

The Rotor PM is an odd looking beast!

The standard Rotor chainrings look flimsy, bendy rings plus the extreme shape is bound to play havok with shifting. I would buy the TT rings! The added stiffness should improve shifting. Adds a bit of weight but lets be honest, if you are going to pay a weight penalty, as close to the BB is the best place to do it. Most of the pros run the TT rings on their Rotor cranks on the road bikes.

I have also noticed that most of the pro's run TT rings as elliptical and equally more run them on TT bikes than their road bikes. (wonder why this is) Although I have not experienced any shifting issues myself, I'm not sure if this is due to the ring or the consistency of shifting offered by Di2 which I run. I can confirm however that the rings are by no means stiff they do flex.
As they wear the teeth also seem to sharpen to some degree, my year old ring would not look out of place on a chainsaw. So this may affect shifting at some point
I think your thoughts are pretty valid based on my own experiences, and I'm equally glad that I'm not the only one who thinks the rotor PM looks a bit

 

[jdtate101]

The Rotor PM is an odd looking beast!

The standard Rotor chainrings look flimsy, bendy rings plus the extreme shape is bound to play havok with shifting. I would buy the TT rings! The added stiffness should improve shifting. Adds a bit of weight but lets be honest, if you are going to pay a weight penalty, as close to the BB is the best place to do it. Most of the pros run the TT rings on their Rotor cranks on the road bikes.

I've tried out some sprinting on the standard rings (with a powermeter) and pushed 1100W max, no flex that I could tell of. As I said in my OP, the shifting is spot on too, easily the equal of my Dura-Ace set.

I have ordered the power2max (in 130 BCD for 53/39 Q-Rings) which I will be using with the TT rings (I'm not happy with the powertap as the wheel keeps going out of true when I rally sprint hard, and it will sold on as a wheelset to a lighter rider....a female friend of mine is interested so it would be ok for her). P2M has the advantage that changing rings has no effect on the calibration of the powermeter.

 

[jdtate101]

I've done about 200miles on the new setup so far, and would stand by my 1st impressions. I'm very happy with them so far and feel that they are a good setup to stick with. The benefits will probably take some time to realise (if I can spot them), but they "feel" right, how much of that is in my head is debatable, but I'm a big fan of the old adage "if it feels right....", so will be sticking with them.

I'll write up another review for the Power2max when it arrives (in Jan some time) as it's probably of interest to some people.

 

[Rob3rt]

How many readings per crank revolution do the p2m make?

BTW, looking back at your images, I think you MAY have the big ring 180 degree's out of alignment. That silver metal tab/pin should (as is usual) be located behind the crank arm, it serves the purpose of stopping the chain getting jammed between spider and crank arm if you toss the chain outwards. Maybe there are 2 of these on a Rotor due to the adjustability, I do not know, just thought I would mention it in case

 

[jdtate101]

How many readings per crank revolution do the p2m make?

BTW, looking back at your images, I think you MAY have the big ring 180 degree's out of alignment. That silver metal tab/pin should (as is usual) be located behind the crank arm, it serves the purpose of stopping the chain getting jammed between spider and crank arm if you toss the chain outwards. Maybe there are 2 of these on a Rotor due to the adjustability, I do not know, just thought I would mention it in case

Indeed there are two and one is hidden behind the crank arm. My rings are in the default "3" position which is recommended when you start out with them, you then move them to other positions (5 in total) to fine tune to your ride style.

I only got the p2m yesterday (fitted to the bike and went for a quick 20mile test run). It's a 130BCD with 53/39 aero q-rings, and seems a good solid piece of kit. I'm not sure on the sampling rate of the p2m, but the ANT+ broadcast is on a 1sec basis, and it now does a left/right balance calculation based upon the load on the spider on each half of a revolution (so I can only assume it samples more than once per crank revolution). There's more details on the p2m site about how this left/right system works.

I'm going to do a few more trial runs with it and then I'll put up a full review on here in a few weeks time.

 

[Rob3rt]

Nice to hear you got the unit.

Yeah I know about the p2m's general spec, I was going to buy the Rotor 3D+ p2m, but decided to get a Quarq (coincidently, it just arrived about an hour ago) as I got a decent price on it and it was very light and matched my groupset (My groupset weighs a few grams over 2kg including the power meter). It is the newest iteration of the Quarq and thus also offers virtual L/R data as the p2m does, also has a few other small but nice features such as having the ANT+ ID on the outside and a little troubleshooting LED. Not Quarq are owned by SRAM, there is quite a big presence in the UK and thus a few places to go for help in person if need be.

I just had a discussion with a power meter salesman and he told me that the number of sampling points on a power meter can cause an elevated power reading when using Q-rings or similar, it will be consistant, so it is not a problem until you try to compare your power with and without a Q-ring. He said in the range of 5-7W is not unusual when running say a Quarq with a high sampling rate vs an SRM with a lower rate.

I am new to the use of power meters so have not read up on this, my decision was not made up by the above, in fact I called to ask questions maintly to gauge the helpfulness of the vendor given the cost of the unit, that technical point it is of little concern to me as I am running round rings, just thought I would mention it incase you weren't aware of this or if you knew otherwise.

 

[jdtate101]

Yeah I know about the p2m's general spec, I was going to buy the Rotor 3D+ p2m, but decided to get a Quarq as I got a decent price on it.

I just had a discussion with a power meter salesman and he told me that the number of sampling points on a power meter can cause an elevated power reading when using Q-rings or similar, it will be consistant, so it is not a problem until you try to compare your power with and without a Q-ring. He said in the range of 5-7W.

P2M claim that changing rings won't effect the meter and it won't require re-calibration. I'm going to run a test whereby I'll run my P2M on a ride with my powertap wheel in the back. I'll need two GPS units to record (borrow brothers one), and then I can do a direct comparison, but from what I've seen (and read on the net) running the Q's should make no difference. As I'll only be running the Q's from now on any offset will be consistent, and it's really not a problem as long as the power readings are within the 1-2% accuracy.

I'll write up how it goes....

 

[Rob3rt]

Cool, looking forward hearing your longer term thoughts.

I am excited to fit my Quarq but it may be a week before this happens as the bike needs a full groupset overhaul and I don't have all of the required tools (I need a BB30-Hollowtech conversion shim pressing out for example). It will also be my 1st full groupset install, so will be a bit slower and taking my time.

 

[jdtate101]

One of the reasons why I like the p2m with rotor 3D is that it uses a 24mm axel, which is exactly the same as my old Dura-Ace crank, so I've not had to do anything to the BB in order to change around kit. Makes life nice and simple. I'm going to use the p2m (53/39) for everyday use, and keep the 50/34 non p2m setup for especially hilly events.

 

[Rob3rt]

Yes, sounds convenient, I made my choice based on a similar convenience. My TT frame is bb30 running a Vision Trimax chainset atm, my roadbike is a BB30 frame but with a shim fitted and a Tiagra chainset, so regardless I was going to go with BB30 on whatever PM and revert the road bike to BB30, so I can swap the PM between bikes so I can both train and race with power