# Shimano FC-RS500 crankset Vs. 105 5800 crankset



## chancellor_968

I recently ordered a Charg Plug 4 (2015) which comes with most of the 11spd 105 groupset. One exception is the crank which is the non-series FC-RS500. I am thinking of swapping it out for the 105 5800 (not sure what size to go either). 

Would this be worth the money or are the two essentially the same? The seem to retail at around the same amount ($150).

I am also a little out of touch with what the size of the crank actually does. Any suggestions there. I am look for best performance/versatility and durability for longer rides.

Charge Bikes / Plug 4

wiggle.com | Shimano 105 5800 Chainset | Road Chainsets


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## headloss

Seems like a waste of money to me, unless you want different BCD and/or chainrings. I can't speak for current 11speed 105 but I considered them the same level for ten speed. Doesn't seem like you have any reason to swap cranks other than to have a match?


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## chancellor_968

As long as overall performance is the same very close I see no reason to--I know the 11 speed groupset is in general an improvement over the 10, but when comparing those two cranks I am not sure. If they were equivalent then, they are likely so now too.

Thanks!


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## headloss

The current 105 has the stiffer and ugly chain rings... noticeable performance increase in the real world? I have no idea. I think the RS500 looks better.


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## Sanders

Shouldn't be any performance difference.
So if you think aesthetics justify the dough you have to cough up, go for it.
Otherwise I'd leave it at that.

What do you mean by size?

Crankarm lenght, or chainrings tooth count? Or the BCD size even?


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## chancellor_968

Sanders said:


> Shouldn't be any performance difference.
> So if you think aesthetics justify the dough you have to cough up, go for it.
> Otherwise I'd leave it at that.
> 
> What do you mean by size?
> 
> Crankarm lenght, or chainrings tooth count? Or the BCD size even?


I guess I mean all of them--How does each one affect shifting/pedaling. I do mostly touring and recreational back road riding. This bike, given Charge's intent of the design is probably already set up for that.

I assume crank arm length has mostly to do with rider comfort.

What kind of riding calls for what arrangement of teeth?

I appreciate all of your help.


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## Sanders

The simplest one is BCD, it means Bolt Cirlce Diamiter and is the size in which the chainrings are bolted. 110 mm and 130 are the most common.
It has nothing to do with performance or comfort, it's just a mechanical thing.
If you ever want to replace your chainring, you'll need to match the size.

Crankarm lenght is the lenght of the crankarms on both sides (doh).
Common sizes are 170, 172,5 or 175 mm. But some brands go beyond that.
It's a size to fit your body, much like the lenght of a stem, or handlebar reach.
A bike fit would tell you wich size you need, and there are some online calculators. 
I wouldnt worry to much about it as 172,5 seems to be the sweet spot for the mayority of people. You could look into it if something doesn't feel right for your body. But I doubt that would be the case.

Now toothcount on your chainrings. This will determine how hard you'll have to pedal.
So depending on your age, power, fitness you will have to get the one that suits you.
A 39/53 is a standard, but also the hardest gear, it has the biggest rings both outer and inner.
50/34 or 50/36 make a Compact, which makes for an easier gear. Some older people really reap the benefits of this, or people who live in hilly terrain or long stretching climbs. Where a standard set-up just won't do them any good.
52/36 is a Mid Compact, and will have a bit of both worlds.
There is no 'best' set-up, there is only 'best for you'.


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## headloss

Just to add a bit to what Sanders said..

BCD Campagnolo is 135 and the smallest chain ring is 39teeth. 130 allows for a 38t, 110 (compact) allows for 34t. Triples usually have a second BCD for the smallest ring at 74 which allows for a 24t small chain ring iirc. So BCD determines how low you can go.

Longer crank arm means more leverage. Smaller allows faster spinning... it has a marginal impact on the efficiency of your pedalling depending on riding style.
Crank arm length also affects saddle height and thus how far your knee goes above the top tube in the pedal stroke. It affects how you are balanced on the bike. Thus why it's a fit issue.



chancellor_968 said:


> I do mostly touring and recreational back road riding.


absolutely no reason to upgrade then, unless you want to run different sized rings (it's usually cheaper to buy the crank than to replace the rings with OEM parts).


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## chancellor_968

Sanders said:


> The simplest one is BCD, it means Bolt Cirlce Diamiter and is the size in which the chainrings are bolted. 110 mm and 130 are the most common.
> It has nothing to do with performance or comfort, it's just a mechanical thing.
> If you ever want to replace your chainring, you'll need to match the size.
> 
> Crankarm lenght is the lenght of the crankarms on both sides (doh).
> Common sizes are 170, 172,5 or 175 mm. But some brands go beyond that.
> It's a size to fit your body, much like the lenght of a stem, or handlebar reach.
> A bike fit would tell you wich size you need, and there are some online calculators.
> I wouldnt worry to much about it as 172,5 seems to be the sweet spot for the mayority of people. You could look into it if something doesn't feel right for your body. But I doubt that would be the case.
> 
> Now toothcount on your chainrings. This will determine how hard you'll have to pedal.
> So depending on your age, power, fitness you will have to get the one that suits you.
> A 39/53 is a standard, but also the hardest gear, it has the biggest rings both outer and inner.
> 50/34 or 50/36 make a Compact, which makes for an easier gear. Some older people really reap the benefits of this, or people who live in hilly terrain or long stretching climbs. Where a standard set-up just won't do them any good.
> 52/36 is a Mid Compact, and will have a bit of both worlds.
> There is no 'best' set-up, there is only 'best for you'.





headloss said:


> Just to add a bit to what Sanders said..
> 
> BCD Campagnolo is 135 and the smallest chain ring is 39teeth. 130 allows for a 38t, 110 (compact) allows for 34t. Triples usually have a second BCD for the smallest ring at 74 which allows for a 24t small chain ring iirc. So BCD determines how low you can go.
> 
> Longer crank arm means more leverage. Smaller allows faster spinning... it has a marginal impact on the efficiency of your pedalling depending on riding style.
> Crank arm length also affects saddle height and thus how far your knee goes above the top tube in the pedal stroke. It affects how you are balanced on the bike. Thus why it's a fit issue.
> 
> 
> 
> absolutely no reason to upgrade then, unless you want to run different sized rings (it's usually cheaper to buy the crank than to replace the rings with OEM parts).


Thank you both for your responses. I have learned a few things.


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