Cassette ratios

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Re: Cassette ratios

Postby xmpt » Mon Jun 03, 2013 10:48 pm

Hi all,

I made the decission and ordered a 12-30t cassette for my bike. Fitted it up without any drama, the only adjustment was the b screw on the rear derailer. I also replaced the chain as the original Ultegra one was streched to buggery after only doing about 1000km. I also looked at replacing the freewheel hub as I have managed to rotate the casssette on the hub and dug it into the freewheel case, but decided to let it go. I have only put about 100km on the new set up and the bike is completely different to ride. Thanks for all of your comments
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by BNA » Tue Jun 04, 2013 7:19 am

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Re: Cassette ratios

Postby MREJ » Tue Jun 04, 2013 7:19 am

Goodonya xmpt. Thanks for feeding back.
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Re: Cassette ratios

Postby xmpt » Tue Jun 04, 2013 9:47 pm

MREJ wrote:My wife has Ui2 50/34 with a 30 at the back. She loves it. It runs fine on the small ring, but the shop cautioned against using the 50/30 combo.

I tried it once on the work stand and it stretched the chain out and jammed. A nervous moment there.

I did ask the shop why we couldn't just run a longer chain; there was a reason, but I don't remember it.



The guys at the bike shop who fitted the new chain just sized it little to little as they always do and it was perfect. I am runing a 54/39 front, but I dont see how that would make much difference
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Re: Cassette ratios

Postby durianrider » Wed Jun 12, 2013 12:28 pm

You have a 39 on the front and are complaining about knee issues?

Did you know that many pro's run a 34x32 up steep climbs? These are riders that do around 35 000km a year with team doctors assistance and have BMI around 19.

Get a 34x32 on and let your knees heal. Heck, your cadence will improve along with your cardiac output.

I train with a power meter. I can objectively say that having a 34x28 has made me a much better rider. I only know 1 rider in South Australia that can consistently drop me on a climb too so its not like Im out of shape. ;)
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Re: Cassette ratios

Postby xmpt » Wed Jun 12, 2013 9:39 pm

My cadence is ok it sits at a min of 80 on hills since I swapped for the 12-30t rear with the 39 front. What gives me the problem is the damage to the meniscus as it does not like the pressure but is slowly getting better. Unfortunately I am not in a financial position to have multiple crank sets, as much as I would love to change to a compact crank set, so I have to make do with what I have.

The bigger gear was ok before the damage to the knee as I was able to happily leg press on a bad day 600kg, but alas I will never do that again. Also I will never be a hill climber by any stretch of the imagination as I tip the scales at 124kg with a body fat of 14% and only 179 cm tall, I spent much of my life playing prop in rugby union and riding for fun. The benefit of my strength is it is holding the knee together without surgery but on the same token the muscles fatigue quickly under high loads.
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Re: Cassette ratios

Postby Xplora » Wed Jun 12, 2013 9:55 pm

Durian, I don't think xmpt is quite the same build as Contador ;)

I definitely think going compact or at least semicompact (52/36) would help you a lot xmpt if you're struggling. I'm definitely thinking about having a 32 cog cassette option in the future, because if you are hunting for times, you'll pick up a lot more if you have the beans on the flat and haven't burnt the matchbox - especially if you're taking on a lot of hills.
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Re: Cassette ratios

Postby xmpt » Wed Jun 12, 2013 10:14 pm

thanks for that Xplora. All of the guys I ride with are running compacts. Other than the $ factor I don't want to drop top speed on the flat as I can quite happily spin to high 40 low 50km/h and maintain it unless I hit a reasonable hill. What I have found is that since changing the rear ratio I can sprint short hills which I was not able to do prior. The surgeon estimates up to another 18 months before things will settle fully. I just have to wait and see what full recovery will be. I am not that concerned about times as I just ride for fun and fitness.
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Re: Cassette ratios

Postby vander » Wed Jun 12, 2013 10:52 pm

Dont believe your 125kg and 14% body fat that bodyfat I would guess is incorrect.
If your only hitting high 40s low 50s you wont lose anything going to a compact with an 11-28. 50-11 is a bigger gear than 53-12.
http://sheldonbrown.com/gears/
Dont know how far you are post your knee reco (if you got one), but I wouldnt expect cycling to be effecting it for anywhere near 18months.
In saying that most people will be fine with a 53-39 with an 11-28 if they have a reasonable level of fitness unless they are regularly going up 10%+ hills.
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Re: Cassette ratios

Postby Duck! » Wed Jun 12, 2013 11:41 pm

xmpt wrote:
MREJ wrote:My wife has Ui2 50/34 with a 30 at the back. She loves it. It runs fine on the small ring, but the shop cautioned against using the 50/30 combo.

I tried it once on the work stand and it stretched the chain out and jammed. A nervous moment there.

I did ask the shop why we couldn't just run a longer chain; there was a reason, but I don't remember it.



The guys at the bike shop who fitted the new chain just sized it little to little as they always do and it was perfect. I am runing a 54/39 front, but I dont see how that would make much difference

It'd be due to the greater size difference between the two front rings. The rear derailleur can only carry so much chain to absorb the different "wrap" for the extremes of the gear range. Coupling a wide cassette with a compact (16T difference between the two rings, vs 14 between a "tradtional" 39-53) will reach the limit of what the derailleur can handle. As it is, Di2 derailleurs are officially rated to a maximum rear sprocket size of 28T, so the 30 is asking a lot of it already.
I had a thought, but it got run over as it crossed my mind.
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