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PostPosted: Sun Nov 13, 2011 1:42 am 
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Posts: 689
voodoojar wrote:
I've been running a 46 + 11-28 on one of my bikes for a couple of week now and fast shifts from low to high will throw the chain everytime. I've been having to really slow down the shifts where I'd normally only have to go from small to big in the front. I've also broken a chain climbing on this setup because of the severe cross chaining going on.

You need a chain guide.
http://www.paulcomp.com/ckclamp.html


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Posted: Sun Nov 13, 2011 1:42 am 


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PostPosted: Mon Nov 14, 2011 5:17 am 
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Phill P wrote:
That said battery technology has come along since shimano released Di2 so they need to decrease the size and weight of their battery.


How exactly have the exact same lithium ion batteries we've used for the last 10 years really changed in either size or weight?


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PostPosted: Mon Nov 14, 2011 5:55 am 
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at the current rate of improvement by 2020 electric cars will be viable...especially in europe with ~$6 per liter gas :shock:


http://www.greencarcongress.com/2009/12 ... 91225.html


by 2013 panosonic's 4.0Ah (4000mAh) will be in mass production. 4000 mAh weight is 54g. 1000 mAh ~15gm

for reference - battery capacity of campy's EPS 950mAh. shimano is 540mAH.

src.

http://road.cc/content/news/47635-campa ... ils-inside

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PostPosted: Mon Nov 14, 2011 12:50 pm 
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Posts: 612
Spartan,
I can google "battery breakthrough" and come up with dozens press release articles about "upcoming battery technologies" that supposedly are coming out in the next two years, each dated about 2-10 years ago. That doesn't mean that the technologies are manufacturable or commercially available. It also doesn't explain why the Nissan Leaf, Chevy Volt, and Plug-in Prius all have worse electric range than the EV1 from 15 years ago. I have no doubt there is significant research for improved batteries, it is a major problem. It's just that Moore's law does not apply to batteries.
Comparing Campy's battery to Shimano's is completely inane as an example of improving battery technologies, because it is unclear the total number of cells in each design. If campy just throws in double the cells, you can't say "battery technology is getting better."

There is one simple reason why wireless electronic shifting is not going to happen:
3 separate batteries (4 if you have one for each shifter). I'm annoyed enough to have to recharge my garmin after 3-4 rides. If there's a separate battery for each derailleur and each shifter, it easily negates any weight savings by getting rid of the cables and makes it such a hassle to recharge everything that it's not worth it.


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PostPosted: Sat Dec 01, 2012 1:09 am 
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Joined: Thu Oct 20, 2005 9:01 pm
Posts: 29
Location: canada
I don't see charging as an issue. One four bank charger and plug in each component. How long could that take? 15secs??


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PostPosted: Sat Dec 01, 2012 2:26 am 
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Mario Jr. wrote:
46-11? I would. As would most people with a decent sprint, living in a flat'ish country.


I'd highly caution anyone sprinting with a Q factor like that. If the chain skips/slips it could send you over the bars. During a training session years ago I had someone right in front of me one time decide to goof around and sprint in the little ring.. result.. two broken ribs. Chain skipped and they got thrown forward and to the left... luckily no broken collarbone as well.

I love the idea of that combo for a mileage bike though. Just not for competition.


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PostPosted: Sat Dec 01, 2012 7:13 pm 
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Phill P wrote:
why not asymmetric rear spacing? 140mm spacing with the 10mm added to the DS. Hell take 10mm off the NDS again to save weight


You have to line up the chainrings and cassette anyway, so moving the cassette out moves the chainrings out, which increases Q factor, and you need to left and right cranks to match... so there is no reason to make it asymetrical.

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PostPosted: Wed Dec 12, 2012 8:56 pm 
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edesigner wrote:
Mario Jr. wrote:
46-11? I would. As would most people with a decent sprint, living in a flat'ish country.


I'd highly caution anyone sprinting with a Q factor like that. If the chain skips/slips it could send you over the bars. During a training session years ago I had someone right in front of me one time decide to goof around and sprint in the little ring.. result.. two broken ribs. Chain skipped and they got thrown forward and to the left... luckily no broken collarbone as well


Not sure what you mean by Q-factor, but the chainline would be better on a properly designed single ring set-up than it would be shifting from the little ring.

You'd want basically SRAM 1x11. It doesn't throw the chain because it's designed for single ring.

46/11 is a very big gear: pro cyclocrossers have no problem sprinting in this. With 12, you could:
11-12-13-14-15-16-18-20-22-25-27-30

Or:
11-12-13-14-15-17-19-21-24-27-31-36

Or something in-between.

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PostPosted: Wed Dec 12, 2012 9:03 pm 
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Compatible with 10, 11 and 12 speed cassettes


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PostPosted: Wed Dec 12, 2012 10:48 pm 
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edesigner wrote:
Mario Jr. wrote:
46-11? I would. As would most people with a decent sprint, living in a flat'ish country.


[...]

I love the idea of that combo for a mileage bike though. Just not for competition.

Would be ok for training, but not enough if you want to stay in the front group on the descents, let alone trying to catch back on.

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PostPosted: Wed Dec 12, 2012 11:24 pm 
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djconnel wrote:
edesigner wrote:
Mario Jr. wrote:
46-11? I would. As would most people with a decent sprint, living in a flat'ish country.


I'd highly caution anyone sprinting with a Q factor like that. If the chain skips/slips it could send you over the bars. During a training session years ago I had someone right in front of me one time decide to goof around and sprint in the little ring.. result.. two broken ribs. Chain skipped and they got thrown forward and to the left... luckily no broken collarbone as well


Not sure what you mean by Q-factor, but the chainline would be better on a properly designed single ring set-up than it would be shifting from the little ring.

You'd want basically SRAM 1x11. It doesn't throw the chain because it's designed for single ring.

46/11 is a very big gear: pro cyclocrossers have no problem sprinting in this. With 12, you could:
11-12-13-14-15-16-18-20-22-25-27-30

Or:
11-12-13-14-15-17-19-21-24-27-31-36

Or something in-between.


If you space the BB where the bottom cog would minimize the chain line angle that I guess could work. A cross sprint is nothing like a road sprint typically. You aren't throwing your bike for anywhere near as long or at anywhere near as fast. Remember you are compromising the chain length with those gears you are posting. It has to either 1. stretch out the rear der. a decent amount in your top cog or be somewhat loose in your bottom. Ben Berden seems to opt for door number 1 on this setup. Again I would never, ever race road on a single ring setup. If it ain't broke...


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PostPosted: Wed Dec 12, 2012 11:58 pm 
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wassertreter wrote:
(46-11) be ok for training, but not enough if you want to stay in the front group on the descents, let alone trying to catch back on.


Not optimal, but I've raced with juniors who were restricted to a gear 12.6% smaller than 46/11.

At 120 rpm it's 63 kph = 39 mph. Most good racers can sustain close to max power to at least 120 rpm.

Patterson Pass Road Race is a race with especially fast downhills (gradual, potentially wind-assisted). Here's a random cat 4 data track. He gets up around 70 kph, so in this race 46/11 would be less than optimal, but still doable.

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PostPosted: Thu Dec 13, 2012 1:08 am 
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Location: Santa Cruz, California, USA
Patterson is what got me to give up on 50x12 and buy a cassette with an 11t cog. I can do 120 rpm for long enough to get on someone's wheel on a real descent but I can't do it for 5 miles.

I wonder whose chain Tiso is using, and how long it'll last.


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PostPosted: Thu Dec 13, 2012 5:37 pm 
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eric wrote:
Patterson is what got me to give up on 50x12 and buy a cassette with an 11t cog.


I also got popped on Patterson (E3) on a gradual descent with a tailwind. But I wouldn't have gotten popped had I not been at the back in the first place. And I wouldn't have been at the back if I hadn't descended like a wuss. I do mostly hillclimbs these days.... don't need to worry about that :).

Anyway, the point the chainline on a 1x12 will be less optimal than on a 2x11 is still valid, however. Measurements published in Cycling Science have shown chainline affects efficiency much less (if at all) then one might expect. Indeed in the early days of road racing riders wouldn't use multi-gear hubs because it was felt optimized chainline was critical. Certainly the SRAM 1x11 works well: it won the cross-country world championship. But a key efficiency there is pulleys and chainrings which are specifically designed for chain retention, with teeth specifically mated to the wide and narrow gap pattern in the chain. Such chainrings wouldn't allow front shifting.

It's only a matter of time before we see a similar 1xN group for road. With a 34 or 36 tooth rear cog, you could even go up to a 50 front ring and still have a low climbing gear (50/34 is same as 39/26.5).

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Posted: Thu Dec 13, 2012 5:37 pm 


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PostPosted: Fri Dec 14, 2012 1:18 am 
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Perhaps we won't need to replace our 10spd hubs/wheels with 12spd hubs/wheels. Anybody know ...


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