Replacement for a HollowTech #1 (Trekking) Chainset

[2Loose]

I have a 26/36/48 Deore triple Hollowtech chainset on one of the bikes and I think two of the rings are nearing the end of their life. Checking out the price of stainless rings, it suspect that it may be easier\cheaper to replace the entire chainset.

What are my options? If I move to square taper bottom bracket & chainset or Hollowtech 2, will these 'just fit', or will I need threads tapping or anything so drastic? Could the existing BB be reused?

Ideally a lower gearing would be better 24/34/44 or 46 would be ideal - ideas?

 

[RecordAceFromNew]

I have a 26/36/48 Deore triple Hollowtech chainset on one of the bikes and I think two of the rings are nearing the end of their life. Checking out the price of stainless rings, it suspect that it may be easier\cheaper to replace the entire chainset.

What are my options? If I move to square taper bottom bracket & chainset or Hollowtech 2, will these 'just fit', or will I need threads tapping or anything so drastic? Could the existing BB be reused?

Ideally a lower gearing would be better 24/34/44 or 46 would be ideal - ideas?

If the hollowtech #1 BB/chainset you are talking about is like that in the pic below then it is essentially an octalink 2 system. Which BBs fit and what preparation may be required for outboard/external cup BBs are dependent on the frame, of which you have provided no info.

To find a new chainset to match an existing BB requires the precise spec of the BB, which can be worked out from the knowledge of existing chainset model code (usually stamped on inside face of a Shimano crank arm) and chainline measurement, or better still from the label on the BB itself. However it is often uneconomic and/or too much trouble to track down matching chainsets since chainsets are usually quite a bit more expensive than BBs, and it can be time consuming to research BB requirement for multiple chainsets.

 

[2Loose]

RAFN, thank you very much indeed!
The existing chainset is marked FC-M521 and that little snippet of knowledge makes me feel a lot more comfortable - I didn't realise it was an Octalink system and that simple fact will make it easy to source a replacement in the gearing range I want..

 

[RecordAceFromNew]

RAFN, thank you very much indeed!
The existing chainset is marked FC-M521 and that little snippet of knowledge makes me feel a lot more comfortable - I didn't realise it was an Octalink system and that simple fact will make it easy to source a replacement in the gearing range I want..

No worries. For the avoidance of doubt to confirm it is Octalink 2 you do need to check if not already - many Shimano chainsets were supplied in both Octalink (BB code ESxx) and square tapered (BB code UNxx) forms, including the fc-m521. If your existing chainline is 50mm then that combined with the tech info will pretty much define what spindle length you have got. However you should still measure your frame to be sure whether you have a 68mm or 73mm BB shell in case you are to source another cartridge BB.

 

[2Loose]

Hmmm, was sure that it wasn't square taper but now I'm going to have to have the bolt out to check that is definitely Octalink. Thanks for the tip.