Any question answered...

I seem to recall in the RD-6800 manual there were two methods based on what your largest sprocket was...one was the big-big, and the other was about the line crossing through the jockey wheels being perpendicular to the ground.

Yes, that is in the manual for Shimano RDs, for cassettes with a maximum 27T sprocket. It does work in those limited circumstances - a Shimano RD, a big sprocket ≤27T and a double chainset with no more than 16T difference. The thing is, the other method works for everything, so which would you rather learn?

@mdcc_tester what if we fit a sram mech?

what if we fit a sram mech?

The method works for SRAM too, as shown in their manual

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I'm not arguing one way is the only way, but is there a reason shimano chose to present two different methods? Efficiency? Better shifting? Is this sort of matter in the same ballpark as the TL-FD68 cable routing tool (added complexity for the sake of it?)

And to pre-empt your next question; yes, if you're stupid enough to fit Campag, they have their own weird and vague way of determining optimum chain length.

is there a reason shimano chose to present two different methods?

I can't get inside the head of the guy who wrote the Shimano Dealer Manual (as we must now call it, since they have recently decided that mere cyclists can't be trusted with assembly and maintenance operations more complex than "wipe over with a damp cloth, and take it to shop for anything else"). Given that Shimano RDs float on the B-tension spring, the idea of finding a vertical seems unnecessarily challenging. You could set it up at first with the centres of the two pulleys aligned vertically, and then adjust the B-tension to optimise the gap from the upper pulley to the sprockets and find your vertical was no longer vertical. Perhaps they just gave the 27T instructions so that proper race bikes would be set up like that and would look good in the product shots :-)

I check both of the methods I said because you end up doing the second one anyway as you put the chain on, let's you know what the shortest and longest working chain lengths you can get away with, and sometimes when you're working on bikes where people have mismatched parts it's good to know. I use my thumbs to hold things in combination with some fingers, that's a pro tip you can keep.

The RD angle workflow requires less handling of the chain.

Is this a left only turn lane? Heading North near Euston, transecting Marylebone Road...

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Yes. The arrow under the Prius is straight on, meaning the left hand lane is specifically for turning left.

Buses can go straight on from the left lane there.

And cyclists? I had a low speed t-bone from a cyclist, I turned left from the centre of the 'left turn' lane, pulling away from a red light and the other party did an undertake manoeuvre having momentum from a rolling start and wishing to go straight on.

Yeah I shoulda checked my blind spot to prevent it but I feel it was a leap of faith for them to curb hug a straight vector across that road.

TLDR: no bieks harmed, just egos.

Straight on from that lane should probably be done from the right-edge of the lane.

They were at fault for not being curious about your lack of indication, or ignoring the indication you made.

Arrows painted on roads are not obligatory for cyclists, plenty of "left turn" lanes allow straight on movements for cyclists

Q
after a silver front hub 18h 39mm flange diameter.
anyone know of one, or of a crib sheet or the like?

Hope RS Mono looks like it...

Thanks guys @Greenbank it's a RD-5800 short cage with a front chainring of 36/52. I'd like to change as little as possible component wise, so if I can go with a 11/28 I can live with that.

Short cage version of RD-5800 is:-

Maximum low sprocket 23-28T with double chainset
Maximum front difference 16T, total capacity 33T

Maximum low sprocket of 25T would work.
52-36 = 16T, so front difference is within spec.
(52-36)+(28-11) = 16+17 = 33T, so total capacity is just fine.

So, yes, 52/36 and 11-28 is just within spec for the short cage version.

If it's the medium cage version:-

Maximum low sprocket 28-32T with double chainset
Maximum front difference 16T, total capacity 37T

(52-36)+(32-11) = 16 + 21 = 37T

So you can just squeeze in a 11-32T cassette with a medium (GS) cage version.

Anyone speak French?

I'm trying to find a 300watt PA / sound system to rent in the Poitou - Charentes region....

• Do the French use Watts as a measurement or do they have their own, and if they use watts is it the same word?
  
• what is the French word / phrase for a PA?
  
  

Cheers.

My OnOne Fatty has the steel fork with a straight 1 1/8" steerer. I think the headset spec is ZS44/28,6 | EC49/30.

Have already slammed dat stem, but as the headset bearings are rough, what lower stack options are there than the stock OO Smoothie Mixer (which is currently £39.99)?

Why that specific flange height?

I can't help you as my french is appalling but I stayed in that region last summer, it was a very pleasant two weeks.

Pretty sure you'd get away with 'un système PA de 300 Watt'

Comme ça.

Rebuilding a wheel, hub flange cracked.

what lower stack options are there

You can lower the stack by using a ZS49/30 bottom half, e.g. http://www.evanscycles.com/products/cane-creek/40-series-zs49-bottom-headset-ec026970

Pretty sure you'd get away with 'un système PA de 300 Watt'

Comme ça.

Cheers for that. Helpfully the link seems to.