cvictorh

Thinking about replacing the sunracer 12-32t casette that came with my bike to a tiagra 11-32t casette as its only $50 and would make the entire drivetrain tiagra. I've read that having your drivetrain entirely shimano tends to improve shifting but how noticeable would the difference be and would I notice much of a difference between the 12t and 11t high side? Basically I am curious whether it is a worth while upgrade or if the change would be barely noticeable.

seau grateau

I'm guessing the 12-32 cassette is 10 speed and the 11-32 is 11 speed, which would make this not a viable path.

cvictorh

No. Both are 10 speed. One is just the sunracer csr and the 11-32 is the shimano tiagra 10 speed. it replaces one of the single tooth jumps with a 2 tooth jump otherwise seems pretty similar throughout the gearing just ends up being +/- 1 tooth throughout the entire casette. here is a link to it. https://www.amazon.com/dp/B00WLFTGQQ...v_ov_lig_dp_it

1500SLR

You will miss the 11t if you hammer down the hills. It will add a top speed deficit of about 3mph (or 5km/hr). I ride with two bikes my Giant has an 11-28, and my Trek has a 12-25. I am currently in the process of ordering an 11-28. An 11t cog will give you one more harder gear so you can mash your power going down hill vs spinning relentlessly. Just going down a relatively steep pinch my speed difference is about 27mph vs 30mph. It might not seem like much, but then you also have to account for the fact that I still have more power to put through that cog than what I need. With a 12t cog I don't have enough.

Bikes used to come with a 12-25 or even a 12-27 as standard 10 and 20 years ago, but 11-28 is just an infinitely better standard. There is even a push towards 11-32 as the standard now. However a 32t cog can lead to a situation where you're traveling at less than 4mph while going up hill. At which point you need to acknowledge that you might even be going slower than someone who is grinding up a climb. Unless the gradient is well and truly above 10% for a great extent of time you don't really need a 32t cog.

cvictorh

The shimano one I am looking at getting has the 11t so I would gain 3mph. Sounds like that would be a beneficial gain.

seau grateau

Oh, right on then. Personally, I don't have an 11t on my cassette (12-28) and I've never felt the need for one. The only time I'd ever use it is on long descents, and I descend like a grandma anyway, so it'd be pretty pointless (YMMV, of course). Improved shifting would be a plus if you're noticing poor shifting with your current setup.

1500SLR

You would gain around 3mph while going down hill and some extra power to push through the gear and pedal while going down hill. The difference with a 12t is that I get to around 27mph and feel like I'm starting to run the gear out of its puff. With an 11t cog its still got a whole lot more to give.

noodle soup

sounds like someone doesn't have much of a spin.

HTupolev

If you're doing 4mph in a 32T cog on a current Tiagra drivetrain, on a road bike with 700c wheels, you are grinding. That's less than 60rpm even if you're in the smallest ring on a Tiagra triple!

1500SLR

Sometimes its inevitable if you're dealing with a hill that is above 12% gradient.

San Pedro

FWIW, my 12 tooth cog on my Tiagra equipped bike never slowed me down, at least to my knowledge. With a good wind I could ride at 30 mph, and I once drafted a truck at around 40, though my legs were spinning. Now I might be able to get a better short sprint on my 11, but not sure.

If I could go with a 12-32 eleven speed cassette with my derailleur, I definitely would.

MRT2

Sounds like a pointless thing to spend money on. Replace your cassette when it wears out,not before.

FWIW, I use a 12 - 27 cassette, and my big ring is a 48. I never once felt like I needed an 11 tooth, even at 35 to 40 mph, which is about my limit. On flats, I seldom even use the 12 tooth.

MRT2

How fast are you spinning? According to a gear inch calculator, at 90 rpm, on a 50 tooth big ring, you should be going 29.5 mph, and on an 11 tooth, 32.2 mph. So your 3mph speed difference is true, but frankly, you should be able to increase your cadence for short periods of time, and even if you can't, unless you are racing, 30 mph is pretty darned fast. When I get that fast, my instinct is to coast.

1500SLR

It's not really about how fast your spinning. Its when you get to that speed and it becomes counterproductive. You would gain more and use less wasted energy just spinning by having an 11tooth cog. When you're doing 30mph on a 12tooth cog it becomes counter productive. You maybe need to learn to feel when you're getting the most out of your gear vs. needlessly over spinning.

noodle soup

apparently he can't spin over 90rpm.

1500SLR

There's no need. My name is not Chris Froome. As to descending... Some people are madmen. They just want to go faster... I just want to go faster. 30mph is nothing much to me these days. I do it every other day down hill.

noodle soup

You don't need Froome-like abilities to spin over 90rpms. I agree 30mph is nothing. I live in an area with very few hills, but still hit ~40mph on most rides. 30mph is what you hit in a radar speed-trap sprint.

Kimmo

How often are you on the smallest cog?

How often do you use the cog you'd lose?

Me, I hate wide gears. I'm happy to lose a cog at each end and get a couple more in the middle, because those get used all the time, and it means I can cruise at the highest speed possible for a given effort level instead of either spinning, grinding, or going slower.

Also, 11t is poo - because it's so small it's more of a polygon than a circle, giving rise to chordal action - the crank rpm varies with each 11th of the wheel's rotation. If you want to go faster, bust out a bigger chainring.

woodcraft

Not worth it, not noticeable.

Spent the money on better tires.

1500SLR

There's main streets around here that are marked as 30mph. I just like to annoy all of the car drivers by taking a lane then riding as fast as them.

noodle soup

you don’t need an 11t cog to do that. 50x12 gets me easily into the mid 30s.

105 isn’t a very high cadence.

San Pedro

Are you saying you regularly cruise at 30mph?

San Pedro

I'm assuming you're hitting 40 on those hills though. I am most likely to get to that speed on short hills actually because they're more likely to be straight.

1500SLR

No I was saying I practice my sprints sometimes down the main streets of the town I live in. It started out because there's no bike lanes in those streets but now I just like the looks of people when they see a bike in the lane next to them going as fast as they are.

u235

Not noticable. Wait till you need it.