I just recently had to replace my rings on my Quarq for the first time.

Was worried about he same things. Turned out that it's not as hard as you are afraid of. (I may get corrected on this, tho!)

It was my experience that matching the bolt pattern (4 vs 5) and the bcd (110 vs 130) were obviously a big deal. The hidden bolt vs non hidden bolt thing came up but I could never get clarity on that one. I had SRAM rings on it and replaced them with Shimano rings. I even reused the ring bolts. No prob and the Quarq calibrates the same as before.

I'll be watching this thread closely cuz I have an idea for another one of my bikes.

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"Outwork your talent." Kevin McHale

Don't get hidden bolt. In that case, one of the chain ring bolts is hidden behind the crank arm. That means you use a special back side bolt that you basically press or pound into the big chain ring. That is supposed to keep it from spinning while you tighten it from the other side. It mostly works, but it's a pain in the ass when you change rings and it offers no benefit.

Ironically, the picture in the link is NOT a hidden bolt Quarq. Imagine spinning the spider through 180 degrees. That would be hidden bolt.

THIS is hidden bolt.

Something to think about. You can get a GXP version vs. BB30 along with the appropriate BB if you want like this guy. That gives you the option of switching to other bikes that are not BB30 and also gets you away from the Specialized OSBB world which can at times be a pain in the ass.

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Kevin

http://kevinmetcalfe.dreamhosters.com
My Strava

More or less what Kevin said above. Hidden bolt is mostly just a pain whenever you change chain rings. I think the Quarq BB30 crank sets actually have a long BB30 axle (i.e. not a 'true' BB30 axle), which means that it should fit on most bikes with the proper BB bearings/adapter installed. GXP might be a safer bet, though.

You’ve had good responses here already. You can also consider going with a Quarq DFour or DFour91 models which use 4 bolt Shimano rings and don’t limit you to compact or standard ring sizes.

But I’m afraid that the CT 20% discount excludes Quarq PM’s:(