Chainring replacement

Usjes

Hi,

My chain has started slipping recently when I put it in a high gear and inspecting the chaningring shows that the teeth are severly worn. The bike is a Giant Rapid 3 and the chainrings are FSA 130mm BCD 52/42T which can be removed easily with an Allan key (see photo: https://docs.google.com/document/d/17PQu0lSibsGcT5-m-oUl_8r-PG1mNIp5fh8xNmOIrG4/edit?usp=sharing). I'd like to know if there is anything further I need to look out for when ordering a replacement online ? Is 130mm BCD and 52/42T sufficient ? Looking online I see some parts listed as A-type, some as B-type and some as 'Double' or 'Triple' (eg, 'Shimano 105 FC5700 Chainring' vs. 'Shimano Ultegra FC6500 Double Chainring' vs. 'Shimano Ultegra FC6603 Triple Chainring'). What does this single/double/triple refer to. Can I use any of them as long as they are 130mm BCD or do I need a 'triple' because my spider currently has 3 chainrings attached ?

Thanks,

Usjes.

browsing

Hi Usjes,

Double or triple refers to the number of rings on the front. As you have three, yours is a triple. Any 130bcd chainring will suit. Just try and get roughly the same number of teeth. I *think* the max difference in number of teeth between chainrings is supposed to be 13 so try not to go larger than that.
As far as I know, type A or B, is just a system to match chainrings as there are grooves designed together to aid smooth shifting. Mixing type A and B are fine though but won't result in as smooth shifting which imo is no big deal. I don't think type A or B refers to triple rings though so not really relevant here.

Just make sure you have the correct speed. I assume yours is an 8 speed, so just get an 7,8 or 9 speed ring. As far as I know, 7,8 and 9 are all the same width, they're just different spacing between them on the rear cassette. I presume you've tried replacing the chain first right? That would be my first port of call, then the cassette.

smacl

AFAIK, you can't use a double chain ring in place of a triple for the 42t, as it won't have the ramps used to help the chain shift upwards from the granny ring. If you look at the bike side of your chain rings you see small protruding sections, or ramps, and that is what these are for. You don't have/need them on your smallest chain ring.

Usjes

browsing wrote: »

Hi Usjes,

Double or triple refers to the number of rings on the front. As you have three, yours is a triple. Any 130bcd chainring will suit. Just try and get roughly the same number of teeth. I *think* the max difference in number of teeth between chainrings is supposed to be 13 so try not to go larger than that.
As far as I know, type A or B, is just a system to match chainrings as there are grooves designed together to aid smooth shifting. Mixing type A and B are fine though but won't result in as smooth shifting which imo is no big deal. I don't think type A or B refers to triple rings though so not really relevant here.

Just make sure you have the correct speed. I assume yours is an 8 speed, so just get an 7,8 or 9 speed ring. As far as I know, 7,8 and 9 are all the same width, they're just different spacing between them on the rear cassette. I presume you've tried replacing the chain first right? That would be my first port of call, then the cassette.

I haven't tried anything other than looking for replacement chain rings, the rear casette and the chain look fine whereas the teeth on the outer chainring clearly look worn down (https://docs.google.com/document/d/1qhK4Cm154-zqecJDy0BcT-ZJRhobi-7ZKGGZZY44dCs/edit?usp=sharing)
The speed is another thing that some ads mention but I had been ignoring it as I really cant see how it would have an effect. Anyway, does anyone know where online I can buy replacements ? Given that Giant seems to be a relatively popular brand these days I am kind of surprised that I can't just buy an exact replacement (FSA 130mm 52/42T) off the shelf. From what I have looked at so far (nothing in Ireland) but wiggle or chainreactioncycle in the UK, I can only seem to find replacements by mixing and matching between Shimano and FSA and even at that many of the descriptions dont clearly state whether they are single or double or triple or what speed they are intended for etc. also they seem very expensive, like £80 for the pair. Is there somewhere else I should be looking online ? Or are there some cheaper 'no name' brands that would do the trick, this is just a commuting bike after all.

browsing

Hi Usjes,
It's difficult to see in the pics if you chainring is badly worn or not. Even if it is, it can be hard to tell. You're not comparing the front with the rear are you? The profile on the teeth on the front are very different to allow good shifting up and down on the front. Whereas on the back, they're not jumping too far and have some teeth angled to give nice shifting in certain locations.
I really wouldn't ignore the speeds as it can cause noises up front or the chain not to fit on the front at all!!!(even though with your setup that wouldn't happen I don't *think* but I don't know what speed your machine is.) Have a good read of sheldonbrown.com's article on speeds, and article on chain wear; it'll open you eyes

I would really suggest you change cassette and chain first as I think that's really where your problem lies. Your chain can look normal but still be badly worn. You can buy on the sites you listed and german ones. If you bought a chain wear indicator you might be surprised how worn it is.

Also, as @smacl points out, you can't use a standard double in the middle ring on your crank. I assume though you're only looking at replacing the big(gest) ring?

Let us know how you get on.

Usjes

browsing wrote: »

Hi Usjes,
It's difficult to see in the pics if you chainring is badly worn or not. Even if it is, it can be hard to tell. You're not comparing the front with the rear are you? The profile on the teeth on the front are very different to allow good shifting up and down on the front. Whereas on the back, they're not jumping too far and have some teeth angled to give nice shifting in certain locations.
I really wouldn't ignore the speeds as it can cause noises up front or the chain not to fit on the front at all!!!(even though with your setup that wouldn't happen I don't *think* but I don't know what speed your machine is.) Have a good read of sheldonbrown.com's article on speeds, and article on chain wear; it'll open you eyes

I would really suggest you change cassette and chain first as I think that's really where your problem lies. Your chain can look normal but still be badly worn. You can buy on the sites you listed and german ones. If you bought a chain wear indicator you might be surprised how worn it is.

Also, as @smacl points out, you can't use a standard double in the middle ring on your crank. I assume though you're only looking at replacing the big(gest) ring?

Let us know how you get on.

I have resized that image (https://docs.google.com/document/d/1...t?usp=sharing), and to me the wear is as clear as day. Not sure what browser you're using but if you want to zoom in further you can probably just right click and save to your hard disk. But comparing the biggest chainring to the granny one (or the bits of the middle one that aren't obscured by the chain) I can see that on the granny ring the teeth are symmetric about the top of the tooth (or equivalently the bottom of the 'U'). By contrast some of the teeth on the big ring are almost triangular, worn to a fine point which are actually quite sharp to the touch. Note that the bike was upside down when the photo was taken so when I push down on the peddle the RIGHT side of the teeth would push against the chain to drag it around and that is the side that is worn, so the teeth almost look like they are leaning to the left.
People are suggesting replacing the chain/cassette first but since the chain now slips over the big ring, I have been using only the second ring (+ all casette gears) for days now without problem, it is only when I go to the big ring that it starts to slip and, to my eyes at least, it is the only one that looks worn, unless there is some reason why the teeth on the biggest ring are supposed to be different from the other two?

cdaly_

It's pretty usual for the cassette/chain to wear first and you'll likely find that, after you replace the chainring, your chain is also badly worn and you'll probably end up having to replace chain and cassette as well. In this case though, your big ring looks pretty worn. I'm guessing you tend to mash big gears rather than spinning smaller ones? It might be worth working on your pedalling cadence so that this doesn't happen again.

07Lapierre

If ur chainring is worn, then you will need a new cassette and a new chain as well. the chinrings only wear out if you dont replace the chain often enough

quozl

Is there something you're not mentioning like having replaced the cassette and chain last month? As that would explain it

Usjes

cdaly_ wrote: »

It's pretty usual for the cassette/chain to wear first and you'll likely find that, after you replace the chainring, your chain is also badly worn and you'll probably end up having to replace chain and cassette as well. In this case though, your big ring looks pretty worn. I'm guessing you tend to mash big gears rather than spinning smaller ones? It might be worth working on your pedalling cadence so that this doesn't happen again.

The bike is Giant Rapid 3 and only 3 years old (bought Jan 2011). It is used primarily for commuting but I do use it every day as I rarely leave the house without it. I figure I cant have covered more than 15,000 Km total. Gear-wise I spend the vast majority of the time at the highest gear ratio (biggest chainring, smallest casette cog). The only time I lower the gear ratio is when I come to a stop at lights (I drop down to the Middle chainring and biggest casette cog). As I pull away from the lights I then rapidly shift back up to the highest gear ratio.
Maybe this is an odd cycling style, I've had to replace drivetrains with a few previous bikes, but they were cheaper so the chainring and crankshft etc was all one unit. In this case though the chainring is detatchable and it is the only thing that looks worn, the chainrings always looked and felt different on this bike (relative to the casette). The casette is like it is make of metal whereas the chainrings always felt like they were made almost of plastic (although presumably some lightweight alloy).
As its a commuting bike though I want to get where I'm going without breaking a sweat so I dont plan on spinning like crazy to save wear on the chainring I'd rather buy a more durable chainring.

Usjes

quozl wrote: »

Is there something you're not mentioning like having replaced the cassette and chain last month? As that would explain it

Its only 3 years old so I find it hard to believe that I have replaced the casette+chain and have forgotten about it, but I still have the original receipt so I guess I could check the current components vs. the original spec to be sure. More to the point everyone seems to be saying if one element of the drivetrain is worn replace it all => I would assume it the casette/chain had already been replaced then the chainrings would have been replaced also.
I'll dig through my receipts though maybe I'm just getting senile in my old age.

quozl

Is the small cog on the cassette not completely knackered then?

cdaly_

I do my spinning more to save wear on my knees.

You'll get a replacement ring in CycleSuperStore out Tallaght direction for under €30 though any LBS should be able to get you one.

I'm on the same bike (older model 2008) and on the original chainrings. I've replaced the chain and cassette numerous times since then. Chainrings are slowest to wear so you wouldn't necessarily need to replace them at the same time as chain/cassette.

quozl

Usjes wrote: »

Its only 3 years old so I find it hard to believe that I have replaced the casette+chain and have forgotten about it, but I still have the original receipt so I guess I could check the current components vs. the original spec to be sure. More to the point everyone seems to be saying if one element of the drivetrain is worn replace it all => I would assume it the casette/chain had already been replaced then the chainrings would have been replaced also.
I'll dig through my receipts though maybe I'm just getting senile in my old age.

Ahh I was only messing.

The most common way things would go is that the cassette and the chain would be replaced but the chainrings would be fine.

So replacing the cassette and chain doesn't typically involve replacing the chain-ring. Unless someone leaves the chain until it's in bits and then it'll also wreck the chain-ring.

You seem to be confident that it's only your chain-ring that needs replacing. That seemed weird so people were making sure - with a small element of kidding

I'm serious about the small cassette sprocket though. If you live in only two gears both of which use that sprocket then I dunno how it can't be wrecked after 15000 KMs. It's only got 11 or 12 teeth to share the load unlike your chainring with 50+.

browsing

the only reason people are suggesting replacing everything is because usually if the chain rings are knackered, usually everything is knackered. it's typical to replace chains more often than cassettes, and cassettes more often than chainrings. like cdaly( and most likely like the other guys here) I've replaced a few chains, less cassettes and am still on the same chainrings. I've prob done at least 20k km on them. your big ring does look worn alright so replacing might be a good idea alright. let us know how u get on anyway and what you decide to change.