[Royal1664]

Hi Team,

I recently asked for help with gearing for my race in the Swiss Alps next year and after many top idea this one popped up. Thoughts?

“You could mix the Ultegra 11-28 cassette (11-12-13-14-15-17-19-21-24-28) and the Ultegra 12-30 cassette (12-13-14-15-17-19-21-24-27-30) so the ratio would be 11-12-13-14-15-17 loose and 21-24-27-30 pre fixed”

Has anyone tried this or will the jump be too much? Surely it would be easier to just swap the 12t for the 11t creating less of a ratio jump and still giving you the same effect of a hard pushing gear teamed with the 30t climbing?

Topic

[Royal1664]

Thanks Team!
I now have a
Thanks Team!

I now have a 12-30 fitted so let the winter training begin!!! Cheers for everyone’s help!

Merry Christmas

[5th]

I agree, 12-30 is the way
I agree, 12-30 is the way forward. I’ve hit 85kmh on 50/12 while I’ve gone a couple of kmh quicker on 50/11 its more about tucking and being aerodynamic than spinning your legs to a blur – they will be at that speed no matter what gearing you’re running. And dave atkinson is aboldutely right – work on your lines and stay off the brakes as much as possible, that’ll help your DH speed.

[fukawitribe]

Dave Atkinson wrote:Royal1664

Dave Atkinson wrote:

Royal1664 wrote:

It’s actually a non drafting race so I was just a little concerned as there are three main downhill sections ranging from 10-22km descending up to 12%. How do you work out the ratios for speed? I was tempted to take the TT bike for the top end speed but the climbing would be extreme!! Climbs- Gotthard pass, Furka pass and Grimsel pass

your time descending a pass has very little to do with your biggest gear. it’s much more governed by your lines and your braking.

once you get into the valleys there’s often a flattish-but-downhill section, although i don’t know this route myself. if there is you could conceivably lose some time there, although you’ll need to be averaging well above 30mph to get anywhere near spinning out a 50/12.

Absolutely – here’s the figures for the OP if you’re wondering


Speed (km/h)
Gear 45 50 55 60 65 70
50x11 78 87 95 104 113 121
50x12 85 95 104 114 123 133

(courtesy of http://www.bikecalc.com/cadence_at_speed)

[dave atkinson]

Royal1664 wrote:It’s actually

Royal1664 wrote:

It’s actually a non drafting race so I was just a little concerned as there are three main downhill sections ranging from 10-22km descending up to 12%. How do you work out the ratios for speed? I was tempted to take the TT bike for the top end speed but the climbing would be extreme!! Climbs- Gotthard pass, Furka pass and Grimsel pass

your time descending a pass has very little to do with your biggest gear. it’s much more governed by your lines and your braking.

once you get into the valleys there’s often a flattish-but-downhill section, although i don’t know this route myself. if there is you could conceivably lose some time there, although you’ll need to be averaging well above 30mph to get anywhere near spinning out a 50/12.

[Royal1664]

It’s actually a non drafting
It’s actually a non drafting race so I was just a little concerned as there are three main downhill sections ranging from 10-22km descending up to 12%. How do you work out the ratios for speed? I was tempted to take the TT bike for the top end speed but the climbing would be extreme!! Climbs- Gotthard pass, Furka pass and Grimsel pass

[dave atkinson]

50/12 would give you 30mph at
50/12 would give you 30mph at 90rpm which is plenty for the flat; you might drop back a bit on the more gradual downhill bits but if you can sit in a group you’ll probably not be pedalling much anyway. so i’d go for 12-30

[Royal1664]

I am running a 50×34 setup!
I am running a 50×34 setup!

[Yorkshie Whippet]

Silly question, what
Silly question, what chainrings are you planning to use?

[fukawitribe]

Royal1664 wrote:So the

Royal1664 wrote:

So the decision is basically choose the 12-30 so that the 4400m of climb will be easier on the legs by allowing a higher cadence, but losing a little top end speed on the long descents. Over the 11-28 top end speed which I assume would be a minimal gain as I would be spinning out regardless of the gearing, but suffer more on the climbs!

Sounds a fair assessment to me – for me, one implies a little more suffering but with no bail-out, the other a marginal gain when it’s not really needed. I’d go for the more enjoyable option myself which might let you appreciate the surrounding a wee bit more 🙂

[Royal1664]

So the decision is basically
So the decision is basically choose the 12-30 so that the 4400m of climb will be easier on the legs by allowing a higher cadence, but losing a little top end speed on the long descents. Over the 11-28 top end speed which I assume would be a minimal gain as I would be spinning out regardless of the gearing, but suffer more on the climbs!

[racingcondor]

More usual would be to drop
More usual would be to drop the 14 so that you keep the gaps reasonable but as far up the cassette as possible.

That said I’d just lose the 11 and accept that on some of the less steep descents you’ll lose a little bit of speed (not much though as you’ll be able to get more aero).

Saves both cash from having bits of leftover cassette and you can always spend a bit of time between now and then practicing your spinning on the turbo which will do you good anyway.

[PpPete]

Not done it on 10 speed but
Not done it on 10 speed but for a number of years I’ve been running a custom built 9 speed 12-30 which I built up by butchering two cheap HG50 cassettes.
IIRC they were a 11-32 and 11-34 to give me all the right number of teeth.
Had to grind the rivet heads off the backs to free up cogs from the “fixed” parts.
The shifting ramps don’t line up across the whole cassette, but I cannot tell the difference in shifting performance.

[wycombewheeler]

as long as the mech can take
as long as the mech can take the difference between 11 and 30 teeth it should be ok. I would much rather have a 13 – 11 jump at the top end (18%) than a massive 25% jump in the middle of the block. You would only notice the gap at times when you you need more speed than the 13 teeth and that is pretty rare, and generally at those times you are spinning out downhill anyway.

[DrJDog]

swapping the 12T for an 11T
swapping the 12T for an 11T sounds like the way to go to me. it’s still a fairly big jump 13->11, but presumably at the speeds you’d be going to take advantage it won’t be as noticeable as the 17-21 jump you’d create otherwise.

[Author]

Replies