It used to be in the daze of triple chainsets that top of block was for granny, middle of block for middle ring and bottom of block for big ring, or there abouts. Unless you were racing, and then it all went out the window. The virtues of reducing chain wear, better alignment, rubbing front mechs (unless your running thumbies).

Now a days, its 11 out rear, 1 out front and the chain does it all faultlessly (apparently).

Was it all myth n bow locks???

I used to run every thing from the middle ring and top and bottom half from the big and granny. Only thing that has changed is there are the 2 rings missing that I didn’t get full use of the cassette from.

Even in the days of triple the middle ring covered the whole block with no problems at all as it sits dead center. I now run a double with bash conversion so I still get the full range on the middle ring.

I’m not a fan of 2×10 as the 2 rings are offset slightly and neither can cover the full block. Also for some reason the Granny/middle rings are way too big.

Also dont try converting 2×10 to 1×10 as neither ring sits in the middle and you wont get good chainline across the block. Have a friend who had lots of problems with this – needs to be a 1×10 or a 3×10 chainset.

I don’t think so. I’ve used a 6spd (6 x 9spd sprockets) cassette on my Hope SS hub, I have noticed what seems to be better chain life from a 9spd chain using 1 or 2 rings up front but only 6 at the back as chain angles are reduced. Hard to say for sure though as wear rates are really tricky to quantify and you could just use 6 of 9 on any cassette. Just not replacing chains when I expected to need to based on normal 9spd triple use. A straighter chain seems to be a happier one but it’s only one factor in chain life. Shorter stay lengths will amplify cross-chaining for example.

Sure I read something about efficiency of chain angles and cog sizes a while back (straight and large cogs vs crossed on smaller cogs), variance was a few %, not a lot but enough to make a difference that some might be expected to feel, ie a rohloff in efficient gears vs less efficient gears.

It’s easy enough to space the ring in if you’re using a 2x crank to get around the off set issue. If you’re using ht2 style cranks, depending on your bb spacing sometimes you can adjust the spacers there too.

It’s easy enough to space the ring in if you’re using a 2x crank to get around the of set issue

how?

If you’re using ht2 style cranks, depending on your bbq spacing sometimes you can adjust the spacers there too

Those spacers are there to (amongst other things) line your cranks up symmetrically to the frame. If you change them your feet will be on the squiff. You need to move the ring without moving the crank ideally.

also the non-driveside Shimano cup has considerably less thread depth than the driveside cup so adding too many spacers to the non-driveside can leave your cup hanging on by a couple of threads

Yes. You’re correct. They are options though.

We are taking about the difference of a couple of mm, which, when considering the chain displacement across the block is way less important at the back than it is to front shifting

Those spacers are there to (amongst other things) line your cranks up symmetrically to the frame. If you change them your feet will be on the squiff. You need to move the ring without moving the crank ideally.

Agree, if you can space the ring on a single ring on a double chainset setup but towards the middle that’s the best option. But moving a spacer (2.5mm), while putting the chainset ‘on the squiff’, will be in practice unnoticeable.

[post]It’s easy enough to space the ring in if you’re using a 2x crank to get around the off set issue.[/post]erm doesn’t you chainring want to be where the crank tabs are (I presume most double use 1 set of tabs rather than small ring tabs and large ring tabs? So that puts you straight into running the cranks off centre and the (possible) associated problems.

Ah for the days of the versatility (and long life) of square taper eh?

It’s important, you just have to look on here and see the issues people are having trying to get 1×10 running smoothly.

Ah for the days of the versatility (and long life) of square taper eh?

Even square taper isn’t always that simple.

I’m just finishing a framebuild (from a pile of steel tubes) for my youngest. Using some 160mm 5 arm sqt cranks and a single 28t granny ring (with faced off mounting points to get chainline correct).

Comparing an old 113mm shimano bb to a new 110mm (trying to also get minimum q factor), all of the axle length difference comes off the RHS! So that would effectively be running off centre. Weird.