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I've a Marin San Rafael, 2005. The cassette is an 8 speed 11-28 shimano, exact model number unknown. The chain and freewheel are whatever came with the bike..

I've always thought the chain had a problem, stiff link perhaps, because it would feel like it skipped a tooth/jumped particularly when running on the smallest two cogs and pedalling hard.. everything else has been mechanically good, though lately the freewheel has developed a problem, probably stuck pawls. It's slipped and crunched enough times that I'd say it warrants replacing rather than cleaning and regreasing.. The bike has always been stored indoors, some use in wet weather but mainly dry, and has probably done about 2000 miles. I'm reasonably tall/heavy at 193cm/110kg and live in a hilly region which may have contributed to what I think is a premature failure

So, I'm setting about ordering bits but I'm not sure what to get - there aren't any obvious model numbers on these components and I can't find exact specs on what came as standard

  • If I replace like for like, do chain/free/cassette come as a set?
  • Will any shimano 8 speed cassette fit?
  • Do chains have a standard length and need shortening to suit?
  • What keywords do I need to search (e.g. eBay) for to ensure I get the set of things I need?
  • If I go for upgraded components (cos I don't think I'll be getting smaller any time soon), are there particular keywords to search/look in the tech specs for (e.g. Number of pawls-I've no idea what makes one freewheel more heavy duty than another)?
  • Are they a standard fitment hence a drop in replacement or do other things need to be changed too/do I need to match it to the hub?

I don't use the bike enough to warrant eg a sprag hub and rear wheel rebuild, but l'll be using it regularly, soon

Note, I'm not after particular product recommendations, I'm after knowing how to search for and buy the right set things over the the internet, what things are called, what's needed to ensure the job can be done in one swoop working finding something missing - the mechanics of fitting them is not part of the question either

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    In your second paragraph you mention your freewheel but refer to getting a new cassette. Please reference freewheel or freehub tags on the site to determine if you need a cassette/freehub or freewheel. – mikes Nov 12 '17 at 12:45
  • 2000m mainly dry miles and indoor storage is not likely to wear out a freehub or freewheel. 'Slipped and crunched' sounds more like the chain slipping. The sprockets may also be OK, but 8 speed cassettes are cheap so you might as well replace it with the chain. – Argenti Apparatus Nov 12 '17 at 14:54
  • @mike I'm certain the freewheel is knackered because the pedals turn half a revolution plus before the back wheel engages -cogs turn, wheel doesn't. I haven't spent much on maintenance in 10 years that I've had the bike so I'm not averse to buying a few new bits. Maybe the cassette is wonky, maybe it always has been, maybe the chain too- it's always had some problem and I don't think they're particularly expensive components to take a "replace it and see" approach.. :) – Caius Jard Nov 12 '17 at 18:32
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    @criggie not really sure what maintenance could/should have been applied to the one way ratchet- I suspect it's been faulty from the start. I've owned many bikes (with freewheels, now I know the difference) over the years and none have failed, or been given any specific maintenance. This bike has never been power washed, seldom used in the rain etc.. just something gone knackered. I see things for sale for £20-ish, called a "freehub body" - is it what I need? Or does my bike have its one way ratchet built into the hub that carries the spokes. I suppose I should pull it apart and look.. – Caius Jard Nov 13 '17 at 4:55
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    This question has varied a lot from the original. Now you have enough rep, consider joining the Bicycles Chat for less structured questions :) – Criggie Nov 13 '17 at 9:15
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Your easiest solution is to simply buy another of exactly what you have

  • 8 speed cassette, 11-28 teeth
  • 8 speed chain.

They don't come as a set - you need to buy one of each. Its up to you if you want to get cheaper or more expensive parts. The lifespan and weight is what varies with price.

Depending on wear, your front chainrings might be getting tired. But I've seen some severely worn ones still working fine.

Any 8 speed chain will be fine - you could even mix and match KMC chain with a Shimano cassette. But you need 8 speed chain (possibly labelled as 6/7/8 speed) and you need an 8 speed cassette.

If you want to get a bit more adventurous you could look at a 30 or 32 tooth big cog. This would give you a lower-low gear for hillclimbing. Its totally up to you whether this is required.

Downside of enlarging the cassette is that your rear derailleur might not fit, or it might chatter on the lowest gear.

Chains come in lengths longer than what you need. 114 or 116 links (or half-links) So you shorten them to the same number of links as your old chain.

You'll need tools to do this - there are some special bike tools.

  • Cassette lockring remover (Undoes the lockring retaining the cassette on the freehub)
  • Chain whip (to hold the cassette and therefore the freehub still while using the lockring remover)
  • Chain tool (to shorten and fit the new chain you need a chain tool. Chain will probably come with a one-time use pin, or you can fit a master link to make life easier next time.)

Also need rags and cleaners etc, and possibly chain lubricant.

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    There are plenty of videos on YouTube and on the Parktools site that show the procedure. If you remove the cassette from the hub make sure to check whether there is or isn't a spacer close to the spokes which depends on the type of your hub. If there is one you'll need to leave it in place. Any Shimano 8-speed will fit, I have doubts about the choice that's left because they've moved to 10 or 11 speed. Any 8-speed chain will also fit. If you use a non-Shimano chain like KMC you'll get a master link which removes the hassle of riveting the chain. – Carel Nov 12 '17 at 8:30
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    I doubt the OP will need chainrings unless they've been bashed. My hybrid has very similar hardware and while I'm a little lighter than the OP I always carry a fair bit of stuff. My (entry-level Shimano) chainrings lasted around 10 000 miles of me not changing the chain as often as I should. – Chris H Nov 12 '17 at 9:15
  • @carel - I ride a 7 speed and can still get cassettes for that. There are three Shimano 8 speed cassettes on Wiggle right now - its not dead, and its a lot cheaper than replacing more stuff to get 10 or 11 speed. – Criggie Nov 12 '17 at 9:23
  • Remember to keep the old chain so you can size the new one to the same length (assuming you stay with a 11-28 cassette) – Argenti Apparatus Nov 12 '17 at 14:57
  • Hi criggie, quick one about the freewheel, are there standard/do I just buy anything and it'll fit? – Caius Jard Nov 12 '17 at 18:35
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On the off chance that future users in my position (mechanically competent, but never really done any bicycle maintenance / don't know terms) here are the answers I've uncovered along the way since posting this question:

If I replace like for like, do chain/free/cassette come as a set?

No, but they're relatively cheap components and mostly* inter-compatible so it doesn't matter, just base the buying decision on the number of gears and get chain, cassette etc that are suitable for X gears.

*see last paragraph

Will any shimano 8 speed cassette fit?

Quick bit of terminology: a freewheel is a bunch of cogs and a one way ratchet device. A freehub body is a one way ratchet device. A cassette is a bunch of cogs. A freehub is probably an entire wheel hub (that the spokes mount to) and one way ratchet device. A usable wheel needs to feature cogs, a one way ratchet, hub, (and spokes and so on). How a wheel is composed varies, but 7 speed and earlier tech is probably a freewheel plus hub. 8 speed and later tech is probably a cassette and freehub if it's entry level kit. If higher spec out of the factory it's probably a cassette, freehub body and hub as separable components.

In my case in my entry level bike had a shimano FH-RM30 freehub and the local bike shop advised I couldn't separate it so building a whole new wheel, respoke etc if I wanted to replace the freehub. As it was (and in concurrence with advice here) it was more cost effective to just get a second hand wheel (rim, spokes and hub - not sure if the one I was sold was a freehub or a freehub body plus hub). I also purchased a new cassette and chain, and they fitted the cassette, saving me the need to purchase the relevant tool.

Do chains have a standard length and need shortening to suit?

They need shortening. I purchased a tool and SRAM chain that came with a split link device, making it easier to rejoin

What keywords do I need to search (e.g. eBay) for to ensure I get the set of things I need?

Examine the wheel and determine how it's constructed or look up model numbers to see if the freehub body can be separated from the hub. If it can't, buying another wheel may be more constant effective.

If I go for upgraded components (cos I don't think I'll be getting smaller any time soon), are there particular keywords to search/look in the tech specs for (e.g. Number of pawls-I've no idea what makes one freewheel more heavy duty than another)?

Terminology confusion with freewheel/freehub in my case - there are a litany of upgraded components but the lowest cost path of least resistance is either replacing like for like, or replacing the wheel. The total cost for a second hand wheel, cassette, chain and chain tool was £80 - all I need to do is swap the tyre and tube over and fit the chain (and that doesn't need tools other than a chain linker)

Are they a standard fitment hence a drop in replacement or do other things need to be changed too/do I need to match it to the hub?

My reading led me to believe that freehub/freehub-bodies and cassette pairings are often manufacturer specific, so a cassette from one make may not fit the splines of another. If ordering in a shop, this shouldn't be a mistake as they can be trial fitted there and then, only if internet ordering

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