cassette tooth count
 

My Shimano cassette is the standard HG70 9speed 12-23 with a 53-39 chainring combo.
I ride in the Escarpment region of S Ontario and although I never have to get off and push I'm anerobic at the tops of probably 1/3 of the long step hills. I want to be able to spin a bit quicker. My other (older) roadie has a triple with the 30 tooth Granny....is that ever easy.
Will going up to a 25 tooth make any noticeable difference at all or should i opt for a 27 or 30? The 105 gear train will suck up the chain so I'm not worried about the 27 or 30 being too big.
I don't really need an 11....I hardly ever even use the 12tooth I've got. My average flat speeds are 35 klicks or so and I can do that from a lot of combinations using the smaller middle cogs.
Any experience out there?

Sheldon Brown at www.harriscyclery.com has a gear inch chart.Learn to use it. Don't waste you money going from a 23 t to a 25. Depending on what big cog you are using with the 30 granny, a 30 cog with the 39 may not be low enough.

I don't want or need to get as low a gear ratio on the racer as i have on the bike with the triple. But thanks for the memory jogger about the gear inch calculator. I'd forgotten about it.
Having said that, I don't plan on changing the front 39 ring so I can only work at the backend and, I believe, I'm pretty much maxed out with a 30 cog.

A 12-27 would certainly give you some relief, but it's a question of how much you need, and if you think you're going to get stronger than you are now.

Let us know how you make out, as I also feel that I'm "on the cusp", although I have 12-25 right now, and I doubt that a 27 is going to buy me too much.

Eat more spinach,ditch extra bacon and train harder.

I'd recommend trying a 27 for now, it's a huge jump from your current 23 and may be enough. Don't forget you will need a longer chain (most likely anyway).

Good luck.

Ed

Aye, aye, Cap'n!

Funny

I ride 70-100klicks every sunday and spin on a triner during the week.
Don't really want to work much harder at it LOL. (I'm 52, 5'8" and a fit 138lbs)

I'm just hoping to get a bailout ratio that's lower than what I've got by about 10-15% or so. I haven't had a chance to do the gear calc. at Sheldon's site yet.

Thanks for the reply

I'm East of you and although the hills are not that severe either, any steep grade is a challenge to me as I grind myself into shape.

I have a Shimano 105 crank 30-42-52 and HAD a Tiagra cassette 12-25. I've recently upgraded to the Ultegra chain and Ultegra cassette 12-27. I doesn't sound like much but the difference is noticeable and my recovery is quicker once at the top with a breath or two to spare. You may need to upgrade to a triple also.

[edit:You and I are about the same age, 51, 5'9" @170lbs. You may not have it in the legs anymore (joke) I know I don't, which is why I retired my mint Miele Alfa double and got a triple crank]

BTW: The spec sheet on my Specialized ROUBAIX states Shimano 105, 9-speed 12x25t. We pulled a Tiagra Cassette off the hub !
"Specifications subject to change without notice" says the disclaimer at the bottom of the spec page.........YA.......RIGHT !