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PostPosted: Mon Jun 03, 2013 3:04 am 
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Looking for a lighter weight alternative to the ultegra 12-30. I'm doing a 10,000 vertical 36 mile race and need to keep my cadence up on the steepest sections. This would be a sram/shimano 10 speed cassette.

http://app.strava.com/segments/623325


thanks
Pete


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PostPosted: Mon Jun 03, 2013 7:52 am 
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Durace?

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Shimano Dura-Ace 9000
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Posted: Mon Jun 03, 2013 7:52 am 


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PostPosted: Mon Jun 03, 2013 12:48 pm 
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There is no 30t DuraAce. There is a Sram Red Wifli though.

Sent from my EVO using Tapatalk 4 Beta


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PostPosted: Mon Jun 03, 2013 2:57 pm 
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Joined: Tue Nov 11, 2003 9:47 pm
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Location: Santa Cruz, California, USA
Where? I can find 11-28 Red and 11-32 Red Wifli but no 1x-30.

I had a custom titanium 12-30 cassette made for climbing races (with tight gaps between the larger gears) some years ago. The company no longer makes them.

I think that the benefit from using the right cadence is worth more than the tiny weight gain from a DA level cassette to Ultegra.


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PostPosted: Mon Jun 03, 2013 7:27 pm 
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Recon make a 11-30 Campagnolo Ti Cassette, but only 11-29 on the Shimano Al. It does only weigh 140g though which is pretty insane. I don't know if they make an 11-30 Shimano cassette.

IRD also make an 11-30 I think which is fairly average weight but I think is in line with Dura-Ace kind of weights.


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PostPosted: Mon Jun 03, 2013 7:52 pm 
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Location: Santa Cruz, California, USA
What I have read about the shifting quality of the aluminium cassettes has kept me away. And I really need that 30t for this one race. In fact I will probably try to make an 11-32 work for it.

The IRDs are pretty heavy... heavier than Ultegra. Shifting is not as good as Shimano.

I've thought about making an 11-30 from an 11-25 DA cassette and the last two cogs of an IRD 12-30. That may get tricky to get the spacing right.


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PostPosted: Tue Jun 04, 2013 10:34 am 
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Location: Oxfordshire UK
Err just use the Ultegra 12-30 and save a bit of weight elsewhere instead to compensate? :| :idea:

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PostPosted: Tue Jun 04, 2013 10:46 am 
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Location: Pedal Square
Helluva climb!
The gradient seems to be below 10% mostly, though? Or does Strava not resolve good enough? (Sorry to digress, but it's a nice climb)

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PostPosted: Tue Jun 04, 2013 11:57 am 
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mauiguy: are you gonna go under 2:32?

http://connect.garmin.com/page/activity ... Id=1746967

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PostPosted: Tue Jun 04, 2013 12:51 pm 
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Location: Denver
The SRAM og 1090 is lighter and easier to maintain than the da (almost all one piece) but the biggest it comes in is a 28. Do you really need the 30? The difference in production at 80 rpm in the 39 is .19 meters. Just a thought. You probably know what you need best. Are you running a compact up front?


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PostPosted: Tue Jun 04, 2013 1:19 pm 
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Location: England
Not sure if it's been mentioned, but in case not, make sure your RD is compatible with such a huge ratio or you'll have serious issues (you'll need a long cage).

e.g. SRAM WiFli

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PostPosted: Tue Jun 04, 2013 6:42 pm 
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mauiguy wrote:
I need to keep my cadence up on the steepest sections.


Steeper sections?

Image


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PostPosted: Tue Jun 04, 2013 7:58 pm 
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Location: Santa Cruz, California, USA
I have been able to run 30t cogs with 7800, 7900 and 2012 Red derailleurs.
I think I can squeeze a 32t under the standard Red derailleur with screwing in the B screw. When I tried it the 2nd cog hit the cage when in the big ring but I think that is due to the chain being too short. All this depends on the length of your frame's derailleur hanger.

At 10,000' your FTP is 83% of sea level (according to this: http://www.twowheelblogs.com/how-altitu ... wer-output) but of course it is highly variable between individuals. And you're at the end of the race.


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PostPosted: Tue Jun 04, 2013 8:30 pm 
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Location: Wherever there's a mountain beckoning to be climbed
As a partial offset to loss of power at altitude, note that leaving aside differences in wind at different altitudes (which could potentially be considerable), a given power at a given gradient will result in higher climbing speed at higher altitude than at lower altitude, on account of the lower wind resistance due to the air being thinner with increase in altitude. And I believe there is another factor "helping you out", as the force of gravity will be slightly reduced at higher altitude. So the thinner air (less oxygen) reduces your ability to produce power, but a given power at a given gradient results in higher speed at higher atlitude due to lower wind resistance and decreased gravity. So unless the wind becomes more unfavorable at higher altitude, the study to which eric linked may somewhat overstate the loss in speed which can be expected (of course also leaving aside that you might be more tired after you've already been climbing a while).

Quantifying and netting all these factors together is left as an exercise for the reader.

Edit: This just made me think of another thing. Are there any studies showing the relative effectiveness of EPO and blood doping in climbing as a function of altitude? Of course, I am aware that there is variability in effectiveness across individuals, but perhaps it would be good to segment the population and show the relative effect of EPO within a population segment as a function of altitude.


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Posted: Tue Jun 04, 2013 8:30 pm 


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PostPosted: Tue Jun 04, 2013 9:01 pm 
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Location: Santa Cruz, California, USA
Since the rider is climbing at a relatively low speed, the effect from decreasing air resistance is low. (doing an hour record on the track is a different issue, which is why they use tracks at altitude). But you may be faster on the descent!

In the power chart from Ryder Hesjedal's ride (linked above) his power went from around 400w at the bottom to around 300w near the top. Of course that is probably not all due to altitude.

In my experience in doing a lot of high altitude races (including Mt Evans- 14,100'), the best thing you can do is to be acclimated. I have never been able to get the time to do this, just raced against guys who have. If you can't, then show up as soon as possible to the event, like the night before. It also seems that each successive high altitude race makes the effect a little less in the next one, but that may be me getting used to the effect altitude has on me rather than any sort of long term acclimation.

I don't know about EPO but Viragra and Cialis helps some people's athletic performance at altitude. I know a Dr doing research on mountain climbers. However some people respond and others do not. Last I looked WADA was considering proscribing it buit had not done so.

For high altitude long climbing races I like to have lower gearing than I think I will need. That way if I am wrong or having a bad day I can still turn the pedals over.


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