[ClubSmed]

I am hoping that someone here can help me with a question I have

When I replaced the crankset when my FSA Omega died I went for the 105 (5800) to match the rest of my groupset. I made the decision (mistake?) of getting a standard rather than compact crankset but now want to change my mind. Is it as simple as changing the chainrings or do I have to buy a whole new crankset?

Topic

[ClubSmed]

fukawitribe wrote:

It’ll be fine, as long as they are 4-arm 110 BCD Shimano compatible chain-rings 🙂 Not sure why some people were insisting that they were different whilst ignoring the facts, it’s not like it’s an opinion piece… hey ho.

They are 4-arm original 105 11 speed chain rings so looks like they will fit fine.

fukawitribe wrote:

Edit : Nice price btw.

Thanks, I was lucky enough to find someone selling them on eBay who had ridden them for 500 miles before changing to Q Rings.

[fukawitribe]

ClubSmed wrote:

I have already managed to get hold of the rings for just £39 but wanted to make sure that I can swap them over before potentially spending a rather fruitless afternoon trying to fit them. As opinion seems to be divided on this it looks like I am going to have to give it a go anyway 🙂

It’ll be fine, as long as they are 4-arm 110 BCD Shimano compatible chain-rings 🙂 Not sure why some people were insisting that they were different whilst ignoring the facts, it’s not like it’s an opinion piece… hey ho.

Edit : Nice price btw.

[ClubSmed]

Pabloid wrote:

Funnily enough I did exactly same as you (replacing fsa omega with 105 5800 but failed to order 50/34). I contacted online retailer & sent it back. Have now ordered correctly along with bbr60 bottom bracket, some grease & a bb tool & i’ll swap over later this week. 

If you stick with rings you have, i think you’ll have to account for chain length & adjust accordingly.

If shop won’t have it back i’d cut losses and ebay it & re buy correctly i’m afraid. Good luck.

Unfortunately I did a tour on the bike immediately after fitting it so there is no chance of returning it. I did realise my mistake before fitting it but if I hadn’t fitted it I would have missed out on the tour and I did not want to do that.

I have already managed to get hold of the rings for just £39 but wanted to make sure that I can swap them over before potentially spending a rather fruitless afternoon trying to fit them. As opinion seems to be divided on this it looks like I am going to have to give it a go anyway 🙂

[Pabloid]

Funnily enough I did exactly

Funnily enough I did exactly same as you (replacing fsa omega with 105 5800 but failed to order 50/34). I contacted online retailer & sent it back. Have now ordered correctly along with bbr60 bottom bracket, some grease & a bb tool & i’ll swap over later this week. 

If you stick with rings you have, i think you’ll have to account for chain length & adjust accordingly.

If shop won’t have it back i’d cut losses and ebay it & re buy correctly i’m afraid. Good luck.

[fukawitribe]

guyrwood wrote:

If you google replacement rings for the 5800 chainset, the cost of both rings is WAY more than the cost of a whole new chainset with rings.

~€52 for 50/34 on Rose bikes

https://www.rosebikes.com/article/shimano-105-fc-5800-chainring/aid:786501

 

[fukawitribe]

mavisto wrote:

You will probably be able to get a 39 or maybe 38 tooth inner to fit, but the reason they are classed as compact is because the bcd’s are different.  Normally 130mm on a standard and 110mm on a compact.  On a side note, Stronglight seem to do their own thing.

The BCDs are not different on the 5800, it’s 110mm like the other recent Shimano 4-arm chainsets.

[Woldsman]

5800 chain rings

5800 chain rings “BoltCircle110mm” so states  Chain Reaction Cycles:  http://www.chainreactioncycles.com/mobile/shimano-105-fc5800-11sp-double-chainrings/rp-prod133232

 

Not  an economical replacement for a two chain rings only option. Maybe worth a thought if replacing one only?

[StraelGuy]

If you google replacement

If you google replacement rings for the 5800 chainset, the cost of both rings is WAY more than the cost of a whole new chainset with rings.

[mavisto]

You will probably be able to

You will probably be able to get a 39 or maybe 38 tooth inner to fit, but the reason they are classed as compact is because the bcd’s are different.  Normally 130mm on a standard and 110mm on a compact.  On a side note, Stronglight seem to do their own thing.

[fukawitribe]

kevvjj wrote:

I would assume the bolt circle diameter is different for each. If that is the case then it’s a new crankset I’m afraid.

The 5800 chainset follows the recent Shimano approach of unified BCD – so compact, mid-compact or standard double will be fine.

[Anonymous]

I would assume the bolt

I would assume the bolt circle diameter is different for each. If that is the case then it’s a new crankset I’m afraid.

[JohnnyRemo]

Try on the classifieds to see

Try on the classifieds to see if there’s someone looking to swop like for like.

[StraelGuy]

I’ve just replaced my RS500

I’ve just replaced my RS500 chainset with a 5800 105 set. The forged, shaped rings are so expensive you’d be far better off buying a whole new crankset that trying to buy rings for it.

[peted76]

Should be as simple as

Should be as simple as changing the chainrings and adjusting the chain. 

[Author]

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