Chain Rings

On both my bikes the chains were pretty shot from (in the case of the Giant) all year round riding and in the case of the Scott a lot of summer miles on the Focus and a number of miles on the Scott through the winter (but not in the worst of the weather).

In the case of the Scott the chain set was the original FSA Gossamer from the Focus. On the Focus the I'd done over 8000miles and the Scott has done around 1500 miles. There was quite clearly a lot of wear on the 50T ring, and although there was some on the 34T this was probably OK - given that probably more that 90% of mileage is done on the big ring this doesn't seem unreasonable. I bought a couple of KMC chains (X-93) in preparation but was not prepared to put a new chain on the Scott without new chain rings. The cassette (a Shimano 105 11-28) has a much lower mileage on it as it swapped out the original 12-27.

However getting spare chain rings is both difficult and expensive. Significant internet research suggested that I'd be looking at around £35-50 for the 34 & 50T rings. The pair would be be at least £60. This compares to around £85 for a complete replacement chain set. In addition I was struggling to both find the exact replacement parts (surely they are different for different chain sets?) and somewhere where they were in stock.

After a lot of research I decided to take a different approach and replace the whole chain set. I ordered what I felt was an identical FSA Gossamer unit from Planet-X at a reasonable price and good delivery.

However I was quite surprised (and disappointed) to find that the design had changed. In the version on my bike the bottom bracket pre-load is achieved by a "special" nut that pulls the left hand crank onto the bearings. This is achieved with just a 5 or 6mm key, and then the normal 2 bolts on the crank arm pinch the arm to the shaft. This is the "nut" - just needs an allen key:

On the new design however this arrangement has been completely changed and a special tool is required. After yet more internet research it appears that (a) this tool is hard to source and (b) this tool is very expensive - it is at least £35. This is the tool here:

For reference this is from a US based EBay shop with the link here to save people time in the future: FSA-MegaExo-Crank-Bolt-Lockring-Tool and costs £25 + £15 postage

This is very steep for a tool that might be used once per year, and as I'll explain later compares very unfavourably to the Shimano equivalent which costs about £2!

I decided on this basis that I'd move from FSA and get a Shimano 105 (5700 series) model instead. So I returned the FSA chainset back to PlanetX and got a refund. Coincidentally at about the same time there was a set of drive train reduction email offers from Ribble - so I ordered the Shimano unit for only a couple of £ more. I also ordered the "special" tool at the same time.

Here's the crankset:

And here's the special tool (all £1.69 of a piece of plastic):

The proper description is "Shimano Hollow Tech II Crank Installation Tool TLFC16".

When I took the FSA chain set off I looked more carefully at the 50T chain ring. Two of the teeth were quite damaged:

 



The teeth above the "D" and the particularly the "A" are the broken/excessively worn teeth.

In this picture the wear on the 50T can be seen compared to the relatively low wear on the 34T.

In the end it took about 30 minutes to fit (with the new chain). Here's a few pictures of the Scott with the new chain set fitted: