Bicycle Mechanics - 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.

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.

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

Eat more spinach,ditch extra bacon and train harder.

Aye, aye, Cap'n!

Eat more spinach,ditch extra bacon and train harder.

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 ride in the Escarpment region of S Ontario and although I never have to get off and push I'm anaerobic 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....

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 !