UKC

I cycle a lot. But I know nothing about bikes tech wise. Hoping I could get some advice/info from a bikie type

So I have a roadbike with a Shimano 105 group set. The cassette is knackered and so i'm replacing the cassette and chain (ive done this before no problems) but last time I didnt bother changing the chainring as it wasnt worn. But it is now.

But I cant work out what components i need to buy for the chainring!

I think the group set is fairly old school ish as it has 3 gears at the front. Or a granny gear as people comment It seems the new versions only have the 2 gears. Which is fine. But I cant work out if I can buy the chainrings individually

like so - http://www.wiggle.co.uk/shimano-130-pcd-105-5603-10-speed-outer-chainring/

or if i need to buy the whole unit with the pedal arm as well?

like this - http://www.wiggle.co.uk/shimano-105-5700-hollowtech-ii-double-chainset/

The rear cassette is this model Shimano 105 5700 10 Speed Cassette - if that's of any use. But I cant work out what the front is as the only writing on the gear i can find just says 105 shimano 50-d. How can I work out what's compatible?

Ideally id like to spend the least money as I'm comically poor, and only replace the actually sprockety bit, but ultimately i'll be happy if i can buy the right piece so it actually fits.

Advice would be massively helpful!

Thanks

In reply to Kemics:

You can buy the chainring on its own.

In reply to Kemics:

It is possible to just replace a single chainring, but when I looked into it with my Ultegra chainset it was about £15 more to replace the whole chainset.

In reply to andy:

Yeah, I kind of noticed the same thing. Weird you pay so little extra, yet seem to get way more parts.

Will the new 105 chain rings be compatible with my slightly older set up?

...and if not, how do I work out which size set to buy? like 53/39 x170mm - what do those numbers reference. Sorry for the noob questions

In reply to Kemics:

53 & 39 refer to the number of teeth on each chain-ring, and the 170mm is the length of the cranks.

Do you have a triple chainset?

In reply to Kemics:
The latest 105 is 11 spd so no, they'd be thinner - but any 10spd ones with the same bolt pattern would do, i think.

In reply to Lawrence:

aha, thanks for clarifying that. Yes I have triple chain set.

In reply to andy:

aha, so 10spd is okay. Does it matter that mine is a triple chain set, can I replace two? Are double chain sets just minus the small one. Or is the smaller of the two somewhere between?

ahh I thinking I might just need to go to a bike shop and show them

In reply to Kemics:

Which ring is worn?

In reply to Kemics:
Triple chainrings (yours, if a 10sp, will be the FC 5603 105 chainset) have the middle ring machined with little pins to ensure smooth changing down to the granny ring and up to the outer ring. A stand inner ring (such as found on the double chainset (FC 5600)) from a double may cause shifting problems. If I remember from my cycling days you require a 5 hole 74 PCD ring for the inner ring:

http://www.wiggle.co.uk/ta-74-pcd-zelito-triple-inner-road-chainring-24-30t...


And yes, you can replace as many of the rings as you wish, just check that they're compatible with the FC 5603 chainset.

In reply to Kemics:

If it's the inner ring then: http://www.wiggle.co.uk/ta-74-pcd-zelito-triple-inner-road-chainring-24-30t...

Middle ring: http://www.wiggle.co.uk/shimano-130-pcd-105-5603-10-speed-inner-chainring/

The outer ring should be the same on both double and triples.

In reply to Lawrence:

brilliant. Thanks, HUGELY appreciated!

I've definitely got the 10spd triple chain ring so it must be the 5603 105. That all seems to tally. Tbh I never use the granny ring so i'm just going to replace the outer and middle.

is there a way I can check the 130 PCD spacing to double check it will fit. Or is am I being paranoid?

- http://www.wiggle.co.uk/shimano-130-pcd-105-5603-10-speed-inner-chainring/ that link you put up seems to be the exact thing. Only slight confusion is that it says inner ring but has 39T. My middle ring has 40 (i may have miscounted one) so it seems to match. However, was wondering why it was called the inner? Is that because the tripple chain sets have largely been discontinued so that middle has been demoted to inner?

In reply to Kemics:


As always, Sheldon has the answers...

http://www.sheldonbrown.com/gloss_bo-z.html#bcd
http://www.sheldonbrown.com/cribsheet-bcd.html

In reply to Kemics:

Unless I'm much mistaken the dimension being measured on the picture in the link should be 76.4mm if the BCD is 130mm

http://www.sheldonbrown.com/gloss_bo-z.html#bcd

In reply to Kemics:
Is it definitely worn? - you should expect to see several tens of thousands of miles out of a chainring...

You should only need to replace the chain ring if it is actually causing slippage etc. If your cassette is knackered, I would replace it and the chain and see how you go first.

In reply to Removed User:

Ive used the bike a lot of the last couple years. Ive worn out 2 rear cassettes so figured it was probably time? I spoke to a guy in a bike shop and he said if the teeth are hooking over then it needs replacing. Which I thought they were. However, I like your idea of replacing the cassette alone first and seeing if im having problems. Id be very glad to save the £60

In reply to Kemics:

Well there's no harm in trying. It's not going to wear the chain out any faster contrary to popular belief regardless of how knackered the teeth are.