patentcad

If I lived in friggin Florida I'd have an 11 x 20 only because a 10 speed won't let me have an 11 x 17. And my 18-20 tooth gears would be untouched. Not to mention the 56 x 44 chainrings on the front : ). The 44 x 17 for those gnarly overpass ascents...

steve_wmn

It really doesn't make much sense to build that one. 1 tooth gaps at the big end of the cassette yield much smaller gear ratio changes than they do at the 11-12 tooth end. Putting 19, 20 and 21 tooth cogs on the big end will give you three gears within a 5 gear inch range (on a 39 tooth chainring), where 53x11 is a full 10 gear inches longer than 53x12 all by itself. It's best to use 2 tooth gaps at the big end, to give some meaningful gear changes.

In Florida just use a single speed rear and a double chainring front to provide a headwind and a tailwind gear.

Doggus

you and me both. Unless I can push the speed on level ground I don't wanna be going that fast on this nimbly bike. Esp. with the current threads of carbon fiber exploding and killing everyone in a 50 mile radius.

56/12 and 22/28

My S-Works has a 11T-25T spliced cassette.

I love the gaps.

khuon

That's what Wheels Manufacturing did. Since they're using actual Shimano cogs, it's possible for you to do as well. The only difference is that they respaced for Campy.

Belugadave

I can see by all of these posts that that is why they don't make an 11-25 cassette - none of you would want it. I think it's a great combination. I would hate to be without my 11. I say, 53-11 all the way! I use mine pretty much every ride I go on (lots of hills to scream down). At a cadence of 90 you're only going 34 so it leaves room to power up to a cadence of 120 and hit about 45mph. That's when I drop my friend who only has a 52-12. Remember, this is on steep downhills where you can really let it rip. I spin out at about 49 mph.

azwhelan

Unless you're using a compact.

Al1943

Let the Europeans rage on, my favorite cassette is a 13-26 10-speed (with 53-39 rings).

Al

Portlandonian

There's some descents where I have spun out, and I'm not extremely fit. On a 53-12 going 45 MPH your cadence would be 130, going 50 you would be spinning 145, keep in mind this is possible on flats but when you are going downhill over 45 MPH its a bit scary to be spinning that fast.

khuon

There's another BikeForums member for whom that credo is supposed to reflect a namesake.

botto 

Unless you're racing, why would you want to go any faster than 45-50 MPH?

If the descents are that good where you are, i'd focus on my descending technique not revving it up, if i was you.

then again, i was never a mountain goat, so i relied on the descents to catch back on.

patentcad

>>Unless you're racing, why would you want to go any faster than 45-50 MPH?<<

The only riders that reach 45 mph+ in races that I'm aware of are pros or guys who do races in places like Colorado or Utah where there are long descents. The fastest speed I've ever attained on a racing bike was about 50mph on a SCREAMING descent of a LONG downhill outlide New Paltz, NY - solo on a run weekend ride. USCF races? I don't think you have to worry about topping 45mph too often...

SteveE

I've spun up and reached 48mph with my 52x12 gearing. I was drafting another guy in my club. I only needed a few pedal strokes at high cadence to keep in his slipstream. That said, I'm switching over to a compact crank with 50-34x11-23 from a triple setup. I'll lose my lowest gear but gain a high gear.

wagathon

I just replaced a 9-spd 11-25 with an 11-32 -- on a road bike (takes a little finagling but 105 and Ultegra drs apparently can handle it, even tho their specs say 27T max) -- and, I really do not even need a 12T with the 52T top ring. I'd rather have as many closely spaced gears as possible, ending on the low end, even if I have to give up being able to peddle down the big hills.

mirona

Because going so fast that you think you're going to die is awesome. At least that's my excuse.

galen_52657

Looks like you are missing the 13. I would rather have the 13 than the 11.

galen_52657

Pros hit 60 mph all the time descending mountain stages of the TDF. Off course, having an 11 tooth cog has nothing to do with it....

cydewaze

Me too. The only hope I'd ever have of pushing an 11 is if it were on the backside of a compact crank. The 13 I may actually use once or twice a season.

DannoXYZ 

By the time you outspin a 12t cog on a downhill (45mph+), you're better off tucking in anyway... You're really not gaining much by trying to pedal... If I'm drafting off a guy that's spinning madly at 50mph, I don't even have to pedal. He's cranking as hard as he can and that's getting him maybe from 49mph to 50mph. And I'm having to keep my brakes on to not rear-end him while coasting...

khuon

I'd agree with this. For me, trying to outspin that 12T above 50MPH or so just causes me to bounce all over the place and I end up losing speed. If I tuck in low and maintain good lines, I can hit 60MPH on steep descents without pedal turn.

SanDiegoSteve

I would love an 11-25. I've been running the numbers on Shedon's gear calculator to see if a compact with an 11-23 would be similar. I ride a 12-25 now and the 25 is great in the hills, but the 12 sucks down hill.

This, I will look into more.

ggg300

https://www.slowtwitch.com/mainheadin...r/gearing.html

DigitalRJH

Good point. Better to tuck and glide down the hill until there comes resistance to pedal against as the hill decreases or speed decreases.

CPcyclist

Those who boast about descending with out pedaling care to divulge your weight.

It has been my experience that as a riders weight goes up his dependence on an 11 goes down for the most part. Mass to area ratio skinny guys need an 11 to keep up on the descents but damn most can climb the other way with out going to a 26 like the bigger guys.


Summary

Higher weight more likely to favor a X-26+ cog
Lower weight more likely to favor an 11-X cog
only exception the pro or wannabe pro sprinter

galen_52657

I ride with a guy that can out-descend anybody I know. Pedalling and gearing has nothing to do with it. He has passed me when I am pedalling! And this guy is tiny! About 5' 4" tall.

First off you have to be willing to sit on the top tube, hold the bars on the tops and lay your chest on your hands/bars. That will lower you a good 6". Thing is, with all your weight on the front, the bike gets a little squirmy so it takes some nutz to do it.