xlife

I've just checked the details of my last bike service and it seems they replaced the original SRAM PG850 12-26 cassette with a Shimano HG-70 11-28.

I appreciate that this isn't a like-for-like replacement, but I assume it is suitable - the chain they used is an SRAM PC830 and the crankset is the original supplied with the bike - FSA Tempo 30/42/52.

Is the HG70 any good? Whilst researching it there seems to be a suggestion that it is for older drive trains - "recommended for 1995 and earlier Deore LX / STX-RC and 1999 and earlier 105 drive train", but the bike is from 2011!

Is the HG70 suitable for the other components of the drive train? Can you recommend a replacement chain to go with these components, assuming the HG70 cassette is suitable? I have been getting less than 300 miles before the chain wears, so I wanted to check I haven't been sold something unsuitable. Should I go for the equivalent HG70 chain?

Many thanks for any help, I've spent the last 4 hours researching this and I still don't feel like I'm any better informed!

Cheers

Chris

xjustice09x

The HG70 should be fine. Its an 8 speed cassette like the SRAM PG850. Shimano and sram casettes use the same spacing and are compatible.

The suggestion for older drivetrains is because many older road bikes and mountain bikes used 8 speed cassettes. Many newer bikes have 9, 10 , or 11 speed drivetrains. There still are newer bikes like yours that use 8 speed cassettes.

As far as chains go any 8 speed chain from a major manufacturer like KMC, Shimano, or SRAM should work fine. Just make sure its an 8 speed chain. 9, 10 or 11 speed chains are narrower.

xlife

Thanks for that quick response. So is there no benefit in going for an equivalent HG70 chain (https://www.wiggle.co.uk/shimano-hg70-78-speed-chain/) over a cheaper KMC or SRAM alternative, such as the PC830?
Ideally I want to get more miles out of the new chain than the 250-300 miles I'm getting with the SRAM PC830.
Thanks again!

xjustice09x

I dont think you would notice much of a difference between a HG70 and the PC830. Personally i've had good luck with KMC chains.

You should get much more than 2-300 miles from a chain. If you clean it from time to time and lubricate it regularly you should probably get 1-2000 miles maybe more.

nhluhr

Time Out, Reality Check! I've got 1200mi on my Giant Rapid 3 (2011) and haven't even thought about replacing the chain yet, let alone the cassette. Why are you replacing so early? What kind of lube are you using?

xlife

I'm using Finish Line cross country wet bike lube (https://www.finishlineusa.com/product...untry-lube.htm). I also have a Chain Scrubber (https://www.parktool.com/product/cycl...crubber-CM-5-2) and a chain wear indicator (https://www.parktool.com/product/chai...dicator-CC-3-2). I replace the chain when the .75 indicator drops in easily.

I'm mainly commuting in Bristol, UK, and the commute has quite a few hills, which I power up. This winter has been especially wet so the chain has needed more maintenance. I'm concerned too that I'm only getting 300 miles out of the PC830 chain. I'm trying the Shimano HG70 this time (my last 3 chains were the PC830 and I was getting the same low mileage out of them). Are you using a chain tool to check wear? Or running the chain and cassette until you have gear shifting problems/skipping?
What do you make of the Rapid? Have you made any other modifications?

Homebrew01

Do you replace it when it gets a few dirt specks on it ??

Or is that a typo and you meant 2,500 - 3,000 ?

nhluhr

I typically measure chain wear with a 12" ruler. Once they reach 1/8" 'stretch', I replace them. I'm not there yet with the stock chain. I'm using a heavy gear-oil based lube (Chain-L) that works really well in the wet riding environment of Seattle USA.

The Rapid is one of 4 bikes I currently run - I have it equipped with fenders and a rack for doing errands like going to the grocery store and running the dog. It's a perfectly workable bike. When the parts wear out I'll probably go with a Tiagra flatbar setup on it but for now, the drivetrain is adequate, if not a bit noisy in extremes. The rear wheel has also started to ping under heavy torque and probably needs some tension.

nastystang

250 300 miles. are you sure your reading that right? that would only be about two weeks of riding.

xlife

I wish it was a typo. I'm measuring the distance using a Garmin GPS. For me, 300 miles is about 6 weeks of riding. I wrecked the first cassette so I have been checking the chain wear with the Park Tool frequently and replacing at .75. I clean and lubricate the chain about once a week; basically I'm following the advice of the Giant bike store which I purchased it from, they have been fitting the chains and the cassette up until now (although the most recent chain change I did myself - will see if it lasts any longer this time). Every time the chain has worn out after less than 300 miles, I have queried it with the staff, and they basically have said "it happens". Do you have any suggestions at to what could be going wrong?

fstshrk

If you are wearing chains in 300 miles, there is something very wrong with this picture. I get typically 2000+ miles from a chain.

Homebrew01

User error. Stop measuring and just replace it after 1500 miles or so.

nhluhr

I don't know about "stop measuring" but keep in mind the type of tool you're using exaggerates chain wear by effectively doubling the roller wear. Use a 12" ruler and follow common guidelines for that (typically once length of 24 half-links changes from 12" to 12 1/8", you can consider changing the chain).

xlife

Thanks, I'll bear that in mind. How come a ruler actually does a better job than a bespoke tool from a reputable manufacturer like Park Tools?

nhluhr

A ruler IS the correct tool and Park sells those too.