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Jul 2016
10:02am, 18 Jul 2016
32,404 posts
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Hills of Death (HOD)
RIP Mrs Boardman 
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Jul 2016
10:50am, 18 Jul 2016
3,358 posts
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Mandymoo
Very very sad
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Jul 2016
1:28pm, 19 Jul 2016
9,975 posts
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richmac
bad times for Chris and family.
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Aug 2016
11:45pm, 3 Aug 2016
11,224 posts
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LindsD
Question: does anyone use a Cobi and what do they think about it if so?
OH wants to know....
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Aug 2016
12:40pm, 30 Aug 2016
30,935 posts
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Nellers
A couple of questions for the technically minded amongst you, both resulting from me having ridden mountainbikes when I was younger and now having switched to raod bikes.
1) Chain lines: When I was riding MTBs they had triple chansets and the advice I had was not to use chain lines that were too extreme ie. don't use your smallest sprocket or 2 in your big ring and vice versa, as this would cause excessive chain wear. Is that sttill a thing on a road bike with a double?
2) When I was watching the Olympic Mountain Biking I noticed that they were riding what looked like a single chainset but that they had a big dinner plate of a block to give them the gear range. What's up with that? Or am I misunderstanding what I saw?
Cheers,
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Aug 2016
12:57pm, 30 Aug 2016
4,634 posts
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Winded
1. Yes
2. Yes
Consider my posh ultegra set up. 2 rings at the front and 11 at the back. 22 gears. BUT.... No cross chaining for the small front&aback combo also no cross chaining for the big front/back combo. Best to [not] do that for the top 2 and bottom 2 cogs - so that is now 18 useable gears, now consider the actual gearing - there is overlap, some combinations of front/rear cigs will provide either exactly the same or nearly the same mechanical advantage. If you ignore these you are down to 14 or 15 gears. On a 2x10 set up you are down to about 12.
Having one cog at the front is lighter, better for the chain, easier to find the right gear all of the time and allows a reasonable justification for the otherwise silly 14 speed cassettes the big manufacturers a have patented.
Never have your chain fall off the front cigs too & never have to index it or put a new cable on.
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Aug 2016
12:58pm, 30 Aug 2016
4,635 posts
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Winded
(SRAM say their 2x11 is 22 useable gears but it still makes chains wear faster if cross chaining)
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Aug 2016
1:13pm, 30 Aug 2016
30,936 posts
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Nellers
Thanks for that, Winded.
Are the single ring MTBs a generally available thing or are they specialised (small "s") racing machines for the pros/serious amateurs?
I'm only asking through curiosity. I've got no plans to get an MTB these days.
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Aug 2016
3:14pm, 30 Aug 2016
4,636 posts
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Winded
I think they are mostly a new(ish) variation of higher end gear- though I don't pay much attention to MTB. Coming soon/now to road bikes near you - probably.
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Aug 2016
5:48pm, 30 Aug 2016
1,733 posts
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MudMeanderer
There was musing about road versions earlier in the year, but they don't really seem to have caught hold.
There were quite a few on show during last winter's cross season, so must be able to be fitted to road style shifters. They make sense there when conditions become very muddy.
The rear derailleurs are more complex than usual including a clutch to better keep chain tension (as there is no front mech to act as a chain guide)
At the moment as far as I'm aware only SRAM make a widely available one, and I get the impression it's quite frequently fitted aftermarket and only available on the higher end groupsets.
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