firebird854

Hi,

I'm considering a few crankset options for my Argon-18 117 tri disc. According to https://www.argon18.com/en/bikes/tri...e-117-tri-disc I have a Shimano RS510 52/36 with a Shimano BB Press Fit SM-BB72-41B. I think it's a BB86 (I'm not sure exactly what that is referring to, I just see that tossed around for it online).

I would like a powermeter and am considering either an $800 or below option that includes a crankset or a decent crankset deal then I'll simply purchase power meter pedals.

I recently found https://www.chainreactioncycles.com/.../rp-prod165465 for a pretty nice deal, $155 (more like $135 with their clearance code) for a 619g crankset seems like a pretty outrageous deal, will this be compatible? Will I need to buy anything else?

I'm also considering the Verve Infocrank, it comes in two options:
VERVE INFOCRANK M30 POWER METER
VERVE INFOCRANK 24MM POWER METER

Would either of these be compatible?

Any thoughts or additional recommendations would be quite appreciated, thank you in advance.

Iride01 

If you are going to spend that much money, why not just get pedals that are themselves a power meter? Then you don't need to purchase a new crank and worry about all the things you aren't sure about. Pedals are easy to change and the procedure is simple. Changing a crank and bb will mean matching up a lot of variables. And possibly expensive tools for removal that may not be used for installing the new crank and bb because they require a different expensive tool.

And I don't understand what you mean in this statement........... A crank with a powermeter does not require power meter pedals. And power meter pedals don't require you to change your existing crank.

dsbrantjr

Power meter pedals will work with any modern crankset, until some manufacturer decides to come up with a new! improved! "standard" to replace the 9/16"-20 pedal threads.

firebird854

Yes, I am well aware that a crankset power meter does not also require power meter pedals and vice versa. The crankset that came with my bike is a debranded Shimano anchor, I intend on upgrading it either way. So, my thought process is, I could either buy a crankset w/ a power meter or buy a crankset that is of good value and light-weight and get power meter pedals as I want a power meter regardless. I hope that provides a bit more clarity for my query.

Iride01 

IMO, a half pound saved in the wheels will be much better than a half pound saved in the crank. However I didn't look to see what wheels your bike will have.

smashndash

M30 uses a stepped 28/30mm spindle. This is not ideally compatible with BB86. BB86 uses a 41mm shell diameter and requires a sleeve (nylon, alloy etc) around the bearings. The archetypal 30mm ID bearing for M30 has a 42mm OD and typically needs a 46mm shell including a sleeve. That is to say, you’re going to need a much smaller bearing. And that’s not going to be great for friction/bearing life.

M30 is also a somewhat rare specification by Praxis. BB386 (which also has the same fit issues with BB86) is far more popular and you’re more likely to find BB options. Note that the M30 and BB386 options require new bottom brackets.

TL; DR get the 24mm spindle.

EDIT: can I ask why a Shimano ultegra power meter is not being considered? Slightly heavier than the FSA crank but you get the unbeatable shift quality of Shimano chainrings.

firebird854

I already have Aeolus TLR Pro 5 disc Bontrager wheels so that's taken care of and this bike is beastly heavy, easily 20+ pounds, I'm a climber so I'm trying to lose weight on it wherever I can.

firebird854

Wow, that's an incredibly informative and well put together post, I seriously appreciate it! Regarding Shimano power meters in general, Stages, iiiii precision, etc. I'd want the dual-sided variant and I've been put off to a decent extent by GPLama's blog post: https://gplama.com/2019/06/29/shiman...-power-meters/

Also, for the compatible options you mentioned, M30, or BB386, do you have any suggestions on what bottom bracket should be purchased for it to work?

smashndash

That is a fair reason to look elsewhere. I’m just not sure if it’s a big enough deal to consider leaving behind Shimano shifting and standard/reliable bearings. That decision, of course, is yours.

For BB386, if you have deep pockets: https://www.bbinfinite.com/products/...20970840555579

I’d probably recommend this. It is a one-piece alloy bottom bracket so it will sort of forcefully correct any small defects in your frame and save your bearings a bit. It uses 4030 bearings... which are probably dual row ball bearings? Not sure. Looks custom. $170 for the one piece.

You then have the other solution which is direct fit bearings like: https://wheelsmfg.com/bottom-bracket...-bearings.html

Trek tried this approach of directly fitting bearings into carbon and many, many people have had issues with misalignment, creaking and wallowing out of the shell. And that’s despite being designed for the task. You NEED loctite if you go this route. You’re also more at the mercy of the shell tolerances. BB86 asks for a sleeve around the bearing so that sleeve deforms to compensate for poorly manufactured frame shells. Also, these dual row bearings will have smaller balls than a standard bearing and thus will be more likely to wear out, especially with contamination.

For M30, unless you get a 2mm reducer for a BB386 bottom bracket, pretty much your only option is praxis: https://praxiscycles.com/product/m30-bb86-road/

Their solution seems similar to Wheels mfg but it seems that they went with a ground down standard 6806 bearing rather than a dual row bearing - not sure. If that is true, you will get more “crushing” of the bearing because the bearing stiffness is reduced. In order to achieve similar retention force with less stiffness, there needs to be more interference between the bearing and shell - this means the bearing will get squashed a tenth of a mm or so more than it was designed to. Not great for bearing life. Or worse, you’ll have a bearing that moves around and wallows out your shell (see above).

All in all, using a 30mm spindle in a BB86 shell takes you to the dark alleys of bike engineering. All bets are off, really. It will probably work, but you shouldn’t be surprised if you have issues like the ones I’ve described above.

firebird854

Again, I am blown away by your depth of knowledge on this subject, very impressive. All in all, it seems entirely not worth it to go this route, it would likely be a far better decision for me to simply purchase power-meter pedals and upgrade to a Shimano based crankset, likely Ultegra or Dura-ace down the road (pun intended). I came here before being potentially talked into a purchase that may have some theoretical compatibility by the sales representatives at competitive cycles, wiggle, or powermeter city. Thank you for your advice!

Also, for 100% clarity, the 24mm spindle option for the info crank would also require a new BB correct?

smashndash

“The Verve InfoCrank 24mm power meter uses a Shimano 24mm spindle and works on standard 24mm bottom brackets.”

You should be able to keep your BB.

Iride01 

Many of the crank manufacturers also make the bb's that fit their crank. So if you know that your bike is a BB86 which is a popular size, then just make sure that the crank manufacturer also specs a bb86 that fits that crank.

My 2¢ Why not go with powermeter pedals. That way you can easily switch between bikes with them. You might just get tired of pulling that beast up a hill once you see how many watts you are wasting and get a new bike like I'm trying to do.