Swapping chainrings on a quarq
Until I read the thread "New Dura Ace Gearing" I really had not considered the possibility of swapping chainrings on my Quarq. I currently have a compact 50/34 but there are certainly times I could use the benefit of more on the high end and having a 52t.
A couple of questions about this:
1. Can you use any combination of chainrings as long as they are 110mm (i.e. swap the 50 for a 52 without a 52/36 that was discussed in the other thread)?
2. Is it a "big deal" to swap chainrings. In other words, is this somethign you can "swap back and forth as you please", or is it more of a "I want to change my crank configuration and am should not expect to change it back anytime soon". For example, changing a cassette is easy and quick. But do chainrings require a lot of other considerations other than removing the crank, removing the bolts then re-torquing them?
3. Most importantly, when you remove the chainring bolts and re-torque them, does it mess with the Quarq calibration and require a new FTP test? In the other thread a re-calibration procedure using known weights is mentioned. This seems complicated and maybe puts this into the "big deal" category....
As you can tell, the other thread got me thinking. Many thanks for the wisdom of the gear-heads in the group........
Cheers,
Matt
Comments
Basically if you are using combos in that tool and have the qalvin app you can do it yourself. If you are using a different setup you probably should send it in.
I sent mine in the first time as the qalvin app was not available yet and they swapped them and had it back to me in about 3 days.
I have a ant+ iphone adapter and the app if you need to borrow it to change to offset.
At your w/kg you will be totally fine with 52/36 especially since you don't race IM.
Summary:
50/34 ok
52/34 - not ok
52/36 - ok
As long as the chain length is appropriate and one doesn't mind adjusting the derailleurs then it's not that big of an issue having more than an 16 tooth spread. I have been running an 18 tooth spread for the last year and it's been fine (54/36).
i stand corrected.
Bob is correct, it should work with the proper length chain, just keep in mind for both Shimano and Sram short cage deraillieurs they say the biggest gap should be 16 teeth. It can be done, but typically shift quality goes down and/or you run into issues where you can't quite get the chain lenght right. In otherwords to have enough change for a 52-28, you may have too much when in the 50-11.... but you really shouldn't be riding either of those extreme cross chained combos anyway.
In other words... 52/34 will work but is not ideal. 52/36 on the other hand works great and is just as easy to setup as 50/34.
As Jeff said, once you know the right calibration values for both you can switch them easily. The link I provided as a table of those values and if you stick with combos on that chart you may be able to get by without manually re calibrating.
Related: Interbike is this week and I've asked Sawiris to look into if/how Quarq will work with the new Shimano 11spd stuff. I've already gotten a couple emails from members looking to upgrade to DA11.
While I'm on the topic of Physics questions... How does this work then for the Quarq CinQo Saturn Rotor 3D (with Oval Chainrings) wouldn't this "Calibration Factor" need to dynamically change throughout the pedal stroke?
I have to apologize. I use a 54/39 and not a 54/36. I'm not sure what was in my head when I typed my reply or why I thought I had a 36t little ring.
Nevertheless... appropriate chain length and FD/RD adjustments will allow for a greater than 16 tooth difference. I'll stand by that comment.
@ Matt & John - here's a link to a 12 min video on the quarq site where they describe how to calibrate - http://www.quarq.com/qalvin
@ John - yes the quarq does know what ring you're in - they have many strain gages built into the spider and thru their activation and internal calc's the quarq knows what ring is in use - so yes you do need to calibrate big & small rings - if you 2 sets of rings (50/34 & 52/36) you would calibrate all 4 then record the data for future reference- then when you change rings you input the appropriate data without recalibrating - i had left that detail out for talking purposes - your 2nd question about oval rings - i don't know the exact answer - but i bet they would require a different calibration procedure to get the timing of the "ovality" dialed into complete revolution -
for those reading this w/o power - if you have a rotor crank w/o power you can purchase a tool thru quarq that will allow you to remove the original spider and replace it with a new quarq spider that has the power meter built in - pretty cool stuff
There's another thread running in the gear forum - New DA Gearing by Terry - where similar stuff is discussed
Here's a photo of my son's bike with - DI2 + rotor crank + DA rings mounted on a full dress Cervelo P5 w/Zipp 808's - he changes rings based on race/course configurations
@ Rich - yea he has all the cool toys - but he bought/paid for them - he's a pretty good cyclist @ 4.6 w/kg and a memebr of the USMC tri team