Why?
Let's start off this review with the most interesting question to ask the owner a power meter for a mountain bike; why would you want a power meter on a mountain bike? After several months with the S2275 from Quarq, I can say that I have no idea.
From a functional perspective, the Mountain Bike Version of the Quarq acts just like its road brother the Cinqo. I can't discern differences between the two. In other words 300 watts on one feels pretty much like 300 watts on the other. My perceived exertion falls in line with the NP, Avg. Power, and TSS that I have come to expect from my Quarq S975's.
The differences are figuring out how to train with this device and more importantly, finding a way to use it during a ride or race without risking death.
I strongly believe that anyone that dedicates themself to getting stronger on a road bike could benefit from a power meter. I don't think they have to be a racer, but if they are disciplined and get good guidance via a coach or training plan, the power meter is the most efficient way to improve. Perhaps these gains could be achieved with perceived exertion, but I believe the ability to tie PE to actual effort is not something that everyone is born with. I often think I am at my max when my power meter tells me otherwise and other times I go out way to hard and need the power meter to tell me to back-off. Regardless, the power meter can quantify this like no other device in existence.
However, implementing this device in mountain bike training is a different animal. I've talked to 3 different coaches that I have a great amount of respect for and I have yet to find one that could help me understand how they do or would utilize this device for someone who exclusively trained on trails (especially single track and technical trails). The challenge is the nature of trails and the need to see the feedback from the power measuring unit to get the training benefit. Simply put, on technical trails it is very difficult to hold a consistent power. Cycling power is stochastic by nature, but the changing terrain and even changing geometry of a MTB make steady state interval work very difficult. Traditional intervals like 2 X 20's or 30 second over/unders can only be reliably and safely performed on terrain that would probably be difficult for the average rider to find.
I understand that post ride data may be useful in determining training stress, caloric needs, and relative output changes over the same course. I also understand that the power meter can be useful as a pacing instrument on long climbs or during endurance events where the same segments of track would be repeated multiple times. The device is also beneficial in determining where on a course you would get the maximum benefit from pushing the pace versus backing off and recovering (especially when combined with GPS tools like Strava).
With all of that being said, I do not think the value is there for mountain bikers. For a roadie who likes to ride trails and wants to track TSS, I suppose there would be some level of value, but I'm not sure how many people can justify it as you can significantly upgrade your ride for what one of these cost.
To me it makes more sense to get a power meter for a road bike and perform intervals on the road or trainer. I guess the argument could be made that the MTB geometry is different and that you would not get the same benefit from the intervals if that is your main sport, but that is about the only argument that I see regarding training on an MTB versus the road.
Installation
I should mention that I have the GXP version of the Quarq. I have owned their BB30 version on the road and I must say that there is no way I would go this route on a MTB. I'd rather find an adapter and run a GXP crank as I feel the design was bad for the road and would be even worse for a mountain bike. My main issue is the threaded spacer they use on the non-drive side. I could never get this working correctly as the end would slip and I never felt that I got the proper amount of load on the bearings. It just seems like an afterthought to get a BB30 product to market quickly and I think it was poorly executed.
The installation process for the Quarq is pretty much identical to that of the road version and any other GXP type crank. My Scott has a press-fit 86 BB so with the correct BB, it is simply a matter of sliding the drive-side in, then attaching the non-drive side crank arm and tightening to 40nm. The one downside to press-fit BB's is that the magnet must be epoxied to the chainstay. With my Scott this was a little challenging because of the shape of the stays. I use 3M poster adhesive to get the magnet right before using the epoxy provided by Quarq as you do not want to have to move the magnet after the epoxy dries.
Installation is very straight forward and pretty much anyone should be able to handle this task.
Weight/Stiffness
I do not remember the exact weight of the Quarq, but I do know that it was exactly 60g heavier than the X0 crankset that it replaced which is not bad at all. The stiffness of the crank arms is indistinguishable to me compared to the original cranks. I do feel that the rings are considerably stiffer than the road version. This makes sense because of the much smaller diameter of the 39t vs. the 53t on my road cranks. Shifting has been comparable to the original crankset as well and I have no complaints about the performance of the cranks.
Durability
This one scares me. Out of the box I had major issues with the Quarq. I would get zero offset numbers in the -2300 range and that number would change +/- 500 points during a ride. To put this in context my road quarqs typically return numbers between +/-100 using the calibration function on my Garmins and would rarely drift more than 10 points during a ride. I sent the unit back to Quarq and they replaced the board and sent it back. I installed it and got a return of -470 which was worrisome. By the next day it had moved back to -1300. After another visit to South Dakota, my Quarq was returned with an entirely new unit that has worked flawlessly ever sense. While I was frustrated with the out of the box failure, I must say that Quarq was fantastic to deal with. I am not a big fan of many of SRAM's products, but they stand behind their components as well as anyone in the industry.
Other than the out of the box issue, the Quarq has held up to reasonably harsh conditions. Lots of rain and mud as well as heat and dust and it has kept on ticking. My big worry has more to do with the inherent risks of mountainbiking on electronic equipment. While I have stuck pedals in crits before, it does not come close to the frequency with which my crank arms hit rock, roots or other trail obstacles. The cranks are at a location that is very vulnerable and I have to believe that those impacts at a minimum could change the slope of the unit causing it to give inaccurate readings. Worst case these repeated impacts could damage the unit. I know that SRM states that their cranks could last 10 years or longer. I doubt that would be the case with any mountain bike power meter.
Conclusion
I don't think I would recommend any power meter to anyone unless they knew exactly how they were planning on using it and with a mountain bike, that is extremely challenging, at least for me. However, if you have decided that you definitely want to go that route, I think crank-based is the way to go. I know that SRM now has a MTB option and I am sure it is a good product. However, the value equation simply does not work for SRM. Without user replaceable batteries, their product cost over 3 years is more than twice that of a Quarq and there simply is no way to justify that difference. Powertap is also an option and with a mountain bike there could be less wheel changes making this a viable option, but I don't have any interest in going that route - especially with the industry still debating what the optimal wheel size should be.
-Tony
No comments:
Post a Comment