Bicycle Mechanics - inserting/swapping a gear

I have a 12-25 cassette on my road bike at the moment. How tough would it be to dump the 12 and insert an 18 between the 17 and 19? I believe I lack the right tools, but more importantly, can I buy just the 18 or do I have to purchase a new cassette with the 18 in it?

See related post... http://www.bikeforums.net/showthread.php?t=46829

Thanks!

-mark

I *think* the 17 and 19 are usually secured gears e.g. locked together, at least they appeared to be on the Ultegra cassettes I've been looking at.

Not sure if this means it's impossible to split them and put an 18 between... hopefully someone else here will be able to answer for you.

The 12 is required to lock the cassette to the freehub. You would need to get a different cassette, for that reason, as well as the fact that Shimano has gone to clustered gears, where they are actually cast in combinations, allegedly to keep weight down.

DEMON

Lower-end Shimano cassettes (Sora, maybe Tiagra) are all seperate cogs (I think, seem to remember hearing respacing them for Campy is possible), so you could do it with one of those. But the cogs are designed to be used as a set, even though you can customize them (shifting ramps etc). Have you looked at buying a whole new cassette with the gears you want? I think that'd be your best bet.

Yes, the HG-50 is still separate pieces, as are SRAM cassettes. I have respaced one to work with my Campy. The original question was about adding to an existing cassette, while dropping the one gear you can't- the one that snugs with the lockring- that is why I suggested a new cassette, which of course, could be one that can be configured, but again, you need to keep the smallest cog, since the lockring has to sit next to it in order to lock correctly.

Yes, the HG-50 is still separate pieces, as are SRAM cassettes. I have respaced one to work with my Campy. The original question was about adding to an existing cassette, while dropping the one gear you can't- the one that snugs with the lockring- that is why I suggested a new cassette, which of course, could be one that can be configured, but again, you need to keep the smallest cog, since the lockring has to sit next to it in order to lock correctly.

Thanks guys!

I'll have to go back and think about dumping an internal gear instead of the 12. Can the 25 go (closest to the hub)?

-mark

Thanks guys!

I'll have to go back and think about dumping an internal gear instead of the 12. Can the 25 go (closest to the hub)?

-mark
If you're happy to dump the 12 or the 25, how about dumping both and getting a HG-70 (105) 13-23 cassete?

13-14-15-16-17-18-19-21-23

I assume you're talking about Shimano cassettes here...

If you're happy to dump the 12 or the 25, how about dumping both and getting a HG-70 (105) 13-23 cassete?

13-14-15-16-17-18-19-21-23

I assume you're talking about Shimano cassettes here...


Whoop ... there is it!
(man, I've been looking for a good opportunity to use that phrase for the longest time, whew!)

Thanks Booyah, this is probably what I'll do.

What exactly do I need for this, a chainwhip?

-mark

You'll need a chain whip (http://www.performancebike.com/shop/Profile.cfm?SKU=716) and a lock ring removal tool (http://www.performancebike.com/shop/Profile.cfm?SKU=18241).

The HG-70 ( 105 ) is bolted together and you can , if you have the cogs to swap , have any combination you want . This is not true with the ultegra and durace sets as the larger cogs are mounted on spiders to increase stiffness and lightness but most people are not strong enough for that ( the stiffness factor ) to be importantant .

If you're happy to dump the 12 or the 25, how about dumping both and getting a HG-70 (105) 13-23 cassete?

13-14-15-16-17-18-19-21-23

That is great advice for alot of nonracers. With a standard 53-39 chainring set, this gives a very reasonable range of 46 to 110 gear-inches. If 46 is too stiff a low gear for your knees and local grades, try a 13-25 or even a 14-25.