New cassette / chain advice

short circuit

Hi, in a few coversation with the boardsies on the Saturday spin (whenever I wasn't dying), the coversation came up around the life of cassettes, chains etc and a reasonable ball part was around 3000 - 5000kms for the chain. I did the Sheldon Brown test for chain elongation as well and though it seemed slightly longer, I wasn't sure if it touched the 1/16th of an inch mark or not. But to play it safe, I have decided to change it anyways.

And this has got me thinking on changing the cassette as well. My current cassette as on the Lemond webpage is SRAM PG850 (11-26). I can't seem to find it on any of the websites ... so I thinking what it meant to say was PG850 (12 - 26).

I was hoping to get myself up Wicklow mountains a bit more easily and wondering if it will be a straight swap to a 11 - 30 cassette from one of the below
http://www.chainreactioncycles.com/Models.aspx?ModelID=5212
http://www.chainreactioncycles.com/Models.aspx?ModelID=55

I can't believe that I had to go into the MTB cassette section to find the ratio I wanted ... :eek:

Thanks for your help.

blorg

I don't think your Tiagra rear derailleur will work with a 30 tooth cassette, it is rated for 27T max although you _might_ be able to push this to 28 or 29 (if you could find the Shimano-compatible cassette, which may be difficult with 8sp.)

I can't recall - do you have a standard road double (39T), compact (34T) or triple (30T smallest ring?)

EDIT: The PG 830 11-28 (MTB cassette) might work.

rob1891

I posted to a previous thread with a source that said 30t on a road derailleur would be fine, even 32 at a push, but definitely not 34. The 27t spec is quite conservative.

rob1891

http://www.boards.ie/vbulletin/showthread.php?t=2055295812 no source, it was some other bike forum anyway!

niceonetom

wiggle do a good range of sram cassettes. i can't really advise you knowledgeably as to what the real-world limits of your derailleur are but i would guess that 30 might be achievable. with a standard double (39t small ring) tht would give you a 35 inch gear, which should be plenty (it's very slightly lower than a 34x27 which would be the ultimate gear of most compact set ups).

short circuit

blorg wrote: »

I can't recall - do you have a standard road double (39T), compact (34T) or triple (30T smallest ring?)
quote]

standard road double

rob1891 wrote: »

I posted to a previous thread with a source that said 30t on a road derailleur would be fine, even 32 at a push, but definitely not 34. The 27t spec is quite conservative.

I read the posts on boards previously and your post was what had me thinking of the 30t on the back. Are you still using it and did you manage to iron out kinks with it.

niceonetom wrote: »

wiggle do a good range of sram cassettes. i can't really advise you knowledgeably as to what the real-world limits of your derailleur are but i would guess that 30 might be achievable. with a standard double (39t small ring) tht would give you a 35 inch gear, which should be plenty (it's very slightly lower than a 34x27 which would be the ultimate gear of most compact set ups).

Thanks niceonetom ... it looks like wiggle have both 11 - 28 and 11 - 30 in stock for the PG850 ..

a quick check to see the space between the derailleur and the jockey wheel and out with the credit card ... :cool:

rob1891

No, I use the 27t currently. I only tested with a 32t cassette and haven't tried it again since. I am certain that 30t would be grand. 32t would depend on your specific setup: the position of the derailleur hanger relative to the axle (which can vary!) and the derailleur you are using. For me it was fine, but that is no guarantee to you.

blorg

Well if it works as apparently it will a 30T on the back will give you about as low a gear as a 26T on a compact; should make the hills noticably more comfortable.