Crank/chain ring compatibility advice.

[smutchin]

There are arguably some advantages to the non-series chainset since it gives you a wider choice of options when you need to replace the chainrings.

The benefits of the 105 chainset are ever-so-slightly-lower weight and it looks nicer.

 

[smutchin]

I think the RS500 uses a Hollowtech BB

I just remembered that I recently bought an RS500 BB to use with an Ultegra chainset. No problems with compatibility at all.

 

[si_c]

RS500 series kit is basically what Shimano offer OEMs to help them build to a price, it works equally well, but is slightly less attractive and heavier.

Expect it to last a long time before needing to think about replacement.

 

[PpPete]

There are arguably some advantages to the non-series chainset since it gives you a wider choice of options when you need to replace the chainrings.

The benefits of the 105 chainset are ever-so-slightly-lower weight and it looks nicer.

I just remembered that I recently bought an RS500 BB to use with an Ultegra chainset. No problems with compatibility at all.

I've also recently fitted an RS500 to a friend's bike to use with an otherwise 105 series groupset.
Smutchin speaks the truth about wider choice of options on replacement chainrings - lots of different qualities, prices, tooth counts, (the Spa own-brand ones are particularly good vfm)
Personally I think I prefer the classics looks of the 5 arm (is it that I'm old-fashioned, or maybe I'm swayed by the price differential)

 

[I like Skol]

....... and the new style hidden bolt 4 arm designs have trouble with the Torx bolts working themselves loose.

 

[night cycler]

Why all the worry? The chain set difference is going to make zero impact to the bikes performance. If you hadn't had another 105 bike you would have been none the wiser.

I guess because I seek reassurance on things not familiar to me. When I share with you guys who know about these sort of things I get that reassurance.

 

[si_c]

Personally I think I prefer the classics looks of the 5 arm (is it that I'm old-fashioned, or maybe I'm swayed by the price differential)

I'm the opposite, I far prefer the aesthetics of the 4 arm variant, but only in black. If I was looking at a polished alloy crankset I'd probably want a 5 arm version as I think they look more elegant.

 

[al-fresco]

You do realise that us less observant Cyclechatters are now experiencing an ungovernable urge out to the garage and count the number of 'arms' on our chainsets?

 

[night cycler]

You do realise that us less observant Cyclechatters are now experiencing an ungovernable urge out to the garage and count the number of 'arms' on our chainsets?

Do be sure to check the rotation arrows on the tyres while doing the inspection.

 

[night cycler]

I acknowledge and accept what you have advised me.

In conclusion, if I want to obtain a spare pair of chain rings identical to what is on the Triban bike now, what do I search for? Basically, what are these type of rings commonly known as when ordering spares?

 

[Venod]

A quick google reveals you can get a new RS500 chainset from Rose for £60, you can get a replacement 50t chainring from Amazon for £43, you will need an inner spare as well, so is it worth buying spare chainrings ? of course they may be cheaper alternatives that make it worthwhile.

https://www.rosebikes.co.uk/article/shimano-fc-rs500-crankset/aid:730390

https://www.amazon.co.uk/Shimano-Spares-FC-RS500-chainring-50T-MH/dp/B010QOJK46

 

[smutchin]

if I want to obtain a spare pair of chain rings identical to what is on the Triban bike now, what do I search for?

Aside from the 4/5 arm thing, the most important detail to get right is the Bolt Circle Diameter - this should be marked on the side of the outer chainring (most likely 110mm, given the size of the chainrings fitted, but 130mm is also common).
Here's an explanation of BCD if you want more info, and how to measure it yourself: https://wickwerks.com/bolt-circle-diameter-bcd/

You also need to check the tooth count of your existing chainrings - on your Btwin, that's 52 teeth for the outer chainring, 36 for the inner chainring. Again, this should be marked on the chainrings, or you can count the teeth yourself. If you want to make pedalling slightly easier, you can reduce the gearing by swapping to 50 and 34.

Spa Cycles as mentioned earlier have a wide choice of replacement chainrings at a range of prices, eg: https://www.spacycles.co.uk/m2b0s149p3524/STRONGLIGHT-110-BCD-CT2-Outer-11-speed
https://www.spacycles.co.uk/m2b0s149p3525/STRONGLIGHT-110-BCD-CT2-Inner-11-speed
(these are good quality chainrings, cheaper options are available - you will note, as @Afnug says, that a pair of replacement chainrings is often more expensive than buying a whole new chainset)

 

[night cycler]

Thank you Afnug & Smutchin. That information is very informative and helpful.

 

[night cycler]

I understand what has been explained about the costs-good points..

What I want to establish is exactly what I need for when there is an offer on at some retailer.

So here is the information taken from the actual parts on the bike. A little confusing to me, but I think you guys will know straight away in a definitive way.

Marked on the crank arm on the drive side:
Shimano. FC-RS500.

Marked on the other crank:
FC-R563/R565/RS500
VM ok 175

Marked on the large chain ring:
Shimanpo 11S
52-36 MJ

I have measured the BDC of the 5 bolts. They are all 2&1/2 inches apart.

It is the numbers that I have marked in bold that are confusing me, if you could clarify?

 

[si_c]

I understand what has been explained about the costs-good points..

What I want to establish is exactly what I need for when there is an offer on at some retailer.

So here is the information taken from the actual parts on the bike. A little confusing to me, but I think you guys will know straight away in a definitive way.

Marked on the crank arm on the drive side:
Shimano. FC-RS500.

Marked on the other crank:
FC-R563/R565/RS500
VM ok 175

Marked on the large chain ring:
Shimanpo 11S
52-36 MJ

I have measured the BDC of the 5 bolts. They are all 2&1/2 inches apart.

It is the numbers that I have marked in bold that are confusing me, if you could clarify?

It's the shimano model number - FC = Front Chainset and the R563/R565/RS500 is the chainset model. Some chainsets are identical, but compatible with several model series. In this case the arm on the left side of the bike is the left arm on those three different models. The model on the right, drive side is what you should be concerned with as regards to the chainrings, because that's where they bolt on to.

Also BCD is measured in mm, rather than inches, so it might be worth re-measuring, although it should say on the rings themselves somewhere.