Combining Shimano RS500 crankset with Stages Shimano 105 5800

Question

I've been thinking about getting a power meter for a while now. I finally decided I would get one, but now I realise that Stages only starts at the Shimano 105 level.

I currently have a Shimano RS500 Crankset ( 50 x 34 ) and I'm very pleased with it, so I don't feel a need to replace the whole crankset with a 105 5800.

I also have no plans to upgrade anytime soon to Dura Ace or something like that (the rest of my bike has the 105 5800 set), so I don't think I should buy a higher lever crank arm from Stages.

Now, I know something about bikes, but not a lot. It seems that what I have (RS500) looks compatible with the 105 crank arm (just judging by the looks), but I would like to be certain before I spend this amount of money.

My set: http://www.bikester.be/398351.html Stages I would like to get: http://www.powermetershop.de/en/stages-power-meter-shimano-105-5800

Kind regards and thanks in advance,

Answer 1

Many individuals are running non matching hollowtech II stages crank arms with no ill effects.

Stages themselves cites this as OK.

Note the Dura-Ace crank below.

Crank Compatibility: All Shimano Hollowtech II road cranks

Go ahead and purchase with confidence and enjoy cycling with power.

I run an Ultegra 6800 Stages on a 6700 Crankset personally.

Answer 2

Interesting topic as I just got a DA 7900 Stages and I'm looking to pair it up with a FC-RS500 crankset as well. Stages say that all Shimano non-drive side crankarms can be mix matched with any Hollowgram II so long it is a Road crankset and not mixed with MTBs (one source say from Tiagra to Dura-Ace and others include Sora). I guess the confusion comes in when the FC-RS500 is a non-series road crank. My FC-RS500 is actually paired up with a Ultegra 6600 non-drive crank I had in spare parts because I'd thought it'd be lighter and stiffer since it was hollow forged all around rather than a milled crankarm. I've ran that set-up on a Shimano external bottom bracket for hundreds of miles without any issues.

As for an unbalance weight, I don't think should be a major issue. When Shimano engineers are designing these cranksets they do take it in consideration as an overall design but I hardly see it as detrimental unless you're spinning 200rpm? Just imo.

Answer 3

I think you should go ahead and replace the crankset. If you don't, you risk ending up with an unbalanced pair of crank arms (unbalanced by weight, never mind aesthetics).

Here's a picture of your current set:

http://www.treefortbikes.com/product/333222396443/1339/Shimano-RS500-11-Speed-36-and-46t.html

And here's 105 5800:

https://www.biketiresdirect.com/product/shimano-105-fc-5800-s-crankset

Note that while the two look somewhat similar in terms of the crankarm sculpting, the back side of the non-drive arm is certainly not similar. Your RS500 arm has a "trough" running along its backside, which the 105 5800 arm does not have. This trough firstly prevents Stages from being likely to support the RS500, and secondly makes it clear that the engineering of the two arms is not that similar.