Gearing Question - Hills!

[SnappyPix]

I'm in a bit of a quandry, and I'm wondering if you lovely ladies might be able to help.
Geeky gearing technical question though, I'm afraid.

I'm thinking of doing a bike race later this year, which is nothing short of mountainous (it's called the K2, so that should give a bit of a clue).

My current set up is 53/39 with a 12-25 cassette (9 speed).
I'm having serious doubts about being able to climb with these ratios (although I can just about manage steep-steep hills on this, and am currently doing lots of hillwork for preparation with my local club).

Money is a massive issue so my choices are quite limited with the tweaks I make.
I'm thinking of swopping to a 50/36 for the race/training.
I'm not too keen on losing the higher gears though - and calculate I'll lose between 3-5" per gear with the 12-25 ratios. I could probably stand to lose the highest gear as I only use that usually on descents.
My top gear will go from 116.1 to 109.5
My low gear will go from 41.0 to 37.8

I'm really not sure if changing the chainrings will be a viable option and may end up being more detrimental than helpful (although I'm not sure I'll be able to manage the steepest climb in the race on my current 39/25 set-up.

I'd really appreciate anyone's advice on this.
I've also thought about changing the cassette to maybe a 12-27, which would give a lower low gear, without sacrificing the higher gears and with less of a leap between each.

I'm confusing myself.
What would you do?!!

[DebW]

Are you able to go ride this race course and see if you really need new gears? Are you sure that your current rear deraulleur can take a 27T cog. If so, that will be your cheaper solution (but you might need a new chain, or at least a couple more links). As far as which switch you'd be happier with, I'd look at the current gears you use most and compare them with the new options (ignoring the crossover gears) and make sure you don't lose easy access to something you like in the mid-range, or have a double shift to get between 2 favorite gears. If you do a chainring switch yourself, be sure to move the front derailleur down the seattube until it is as close as possible to the large chainring and pay attention to the cage angle. If you want to swap between the new gears and your current setup frequently, do the cassette swap.

[Pedal Wench]

I'm a Campy girl, but this is what I did.

Last year before a tour in Colorado, I put a 13/29 rear cassette to go with my double crank. It worked out great for climbing, and I didn't notice the lose of the very top gear (53/12 versus 53/13).
I switched out the double for a compact this year. For this year's Colorado trip, I also brought that 13/29. Although this was a strictly recreational ride, I definitely felt the lose of the high end, and I spun out more times than I would care for. If I was racing, I would have been limited. For a recreational ride, it was more important for me to be able to climb.

[SnappyPix]

Thanks guys for your advice.
Unfortunately the race isn't local so sourcing/riding the route isn't really an option.
I've been chewing on gear ratios all day - but I think that the cassette option would be probably the best for me, as only the lowest two gears on both chainrings are different (23 becomes a 24 and 25 becomes a 27).
This gives me a couple of lower gears at the low end, but the mid-range and higher gears are unaffected.
I think it works out cheaper too as the cassette and chain won't cost as much as a chainset and bottom bracket.

Thanks for the warning DebW about the sizing for the 27 cog, I'll have a chat with my lovely lbs.
PedalWench - spinning out is what I'm worried about, especially as there are quite a few steep descents and I don't want to lose speed on the flats.

Thanks again guys, that helped heaps.

[Kano]

Help this newbie with a term please?

Is this the "crazy pedaling" when I'm going too fast for the gear I'm in? Or is it something else entirely?

Karen in Boise

[ridebikeme]

If you simply change the cassette, you will DEFINITELY need to change the chain as well... otherwise you will find it skipping especially with as much pressure as you will need to climb! If you do change and put a compact crank on, as long as you use Shimano, you should be ok and not have to change the front derailleur... otherwise you may have to change that as well. As for losing gears with a compact crank, it's definitely worth the change... your top end gear doesn't get used very often anyway. Nashbar had a compact crank on sale for a very reasonable price... I had a custmer that purchased one... remember though that you willneed a new bottom bracket as well.

Good luck with your ride, sounds lie a great one! We have one her that climbs Mt Washington... it's ranked (professionally)as one of the ten tughest races in the world...