nmnm wrote:the 2x10 options have a grand weight advantage.
In theory, you'd think so. But as we're constrained by what's available on the market we don't need to guess. We can just look at the numbers - I mean, I'd argue that 2 x 5 is ideal and should be lighter but they just don't make the appropriate stuff.I bet if you swapped the largest steel rear cog for a 3rd, small, front chainring you would be about even !
eileithyia wrote:Gosh R2 you were home and logged on quickly this pm!
................................not!!nmnm wrote:In theory, you'd think so. But as we're constrained by what's available on the market we don't need to guess. We can just look at the numbers - I mean, I'd argue that 2 x 5 is ideal and should be lighter but they just don't make the appropriate stuff.I bet if you swapped the largest steel rear cog for a 3rd, small, front chainring you would be about even !
Sram Apex chainset w/ bb = 890g.
Sram 11-32 cassette = 299g
Apex shifter pair = 344g
front / rear mech = 89g (braze-on) / 190g
Is there a 3 x 9 combo that'll get down to that weight? Or a 3 x 7? I do know a shimano 11-32 xt cassette is about 254g (or thereabouts, from memory) so if there's a triple chainset/bb for 940g or below, and we ignore the shifters (say it's for straight bars), and equal the mechs, that'd be a contender..
Fair point. I weigh 11 stones which I'm used to as I carry it around everywhere. I notice the difference between my three bikes' weights enormously. I am trying to minimise my 11 stones, no complacency, as my summer hol plans involve the tourmalet.Oh dear! I hadn't realised we were in a grams war zone
So what you weigh?
It's not a grams war zone (not a war zone at all I hope) but the OP is referring to 105 and Apex, two groups which major on being light. Their weight is very relevant to the way they are marketed and to many (all?) of those who pay extra for them over Deore etc. You take the stance that weight is not an advantage of these double ring groups:and so I mention the stats. I'm not sure Apex is so far ahead of the other options for weight but weight is certainly a relevant factor in a thread where the OP is listing 105 and Apex as his fron-runners, imho.Yep, thats the only plus IMO... narrow Q... Apologies to the OP for going off topic but felt I had to answer.
Mick F, it's 13 pages long.Read this from a year ago
Reohn2 alluded to the Q advantage. I don't know what a U is. CJ suggests a more compact compact double but does note it'd have worse chainlines (which must hurt efficiency) and if you want to pedal along with a tail wind at 25mph, with CJs set-up you'll need to be spinning at 100rpm. I really enjoy turning a slow high gear with a tail wind. The blurb makes a big play of the weight, as I say. I've been tempted by the Apex for weight reasons (currently on 105 and below). Of course, if a triple can hit the same weight / cost balance while fulfilling the gearing requirements, that'd trump these double compact groups perhaps.the compact crankset enables huge savings in terms of element weight, which is especially crucial when confronting demanding climbs where the force of gravity plays against the rider. A reduction of the Q and U factors and less intersection and overlapping of the ratios with consequent better chain alignment are further advantages
It's (enjoyably) preposterous! They have to do their best I suppose, in the marketing department, but I wouldn't want to be heading off to the alps with a 34/29 as my best offer to placate the slopes, no sir!nmnm wrote:In theory, you'd think so. But as we're constrained by what's available on the market we don't need to guess. We can just look at the numbers - I mean, I'd argue that 2 x 5 is ideal and should be lighter but they just don't make the appropriate stuff.I bet if you swapped the largest steel rear cog for a 3rd, small, front chainring you would be about even !
Sram Apex chainset w/ bb = 890g.
Sram 11-32 cassette = 299g
Apex shifter pair = 344g
front / rear mech = 89g (braze-on) / 190g
Is there a 3 x 9 combo that'll get down to that weight? Or a 3 x 7? I do know a shimano 11-32 xt cassette is about 254g (or thereabouts, from memory) so if there's a triple chainset/bb for 940g or below, and we ignore the shifters (say it's for straight bars), and equal the mechs, that'd be a contender..
You say triple + tight cassette < weight than compact + wide cassette. What model is this you suggest? I mean, for the OP (and myself, and others) actually considering the likes of the Sram Apex, who maybe want a 34/32ish gear and don't need to push beyond 30mph on the downhill, we're being bombarded with the excited compact double advertising and might be interested in the triple options if they were pointed out. What are the names of the triple options we can actually buy in a similar price/weight range? Please do include a compatible bb suggestion if it's easy to hand as the non-rotating weight is relevant to my lighter set-up (though of course I pay particular attention to tyre weight and other spinning stuff).Winkeladvokat wrote:
This is all extremely marginal. You're also forgetting that a 12-23 cassette comes in typically at less than 200g, and that bottom bracket weight is neither here nor there - if you're concerned about weight at all (because you're going up a hill, or you're racing) then its rotating weight that counts. weight(Triple crank + tight cassette) < weight(compact + wide range cassette).
Triples are far better for most people most of the time, because the spacing between gears is much tighter, and this has a real-world benefit, particularly when riding in groups. I have, out of a stable of 4 bikes (well, five included in the fixed pub bike!), a touring triple, a road triple, a compact, a standard road double. Personally, the compact is a waste of time - much better to take a triple to the mountains, because you get the goodness of a 53 ring to come down the other side, and you can climb on a standard 30/23 or 30/25, rather than faff trying to get a wide range cassette to give you the same gearing.
I'm just annoyed that campag have dropped triples from its range, it's left me buying up nos campag triple bits
EDIT: sorry, 34/32 is something like 30/26, not 30/23, but the point still stands.
nmnm wrote:You say triple + tight cassette < weight than compact + wide cassette. What model is this you suggest? I mean, for the OP (and myself, and others) actually considering the likes of the Sram Apex, who maybe want a 34/32ish gear and don't need to push beyond 30mph on the downhill, we're being bombarded with the excited compact double advertising and might be interested in the triple options if they were pointed out. What are the names of the triple options we can actually buy in a similar price/weight range? Please do include a compatible bb suggestion if it's easy to hand as the non-rotating weight is relevant to my lighter set-up (though of course I pay particular attention to tyre weight and other spinning stuff).
Sorry for brevity - off to pedal up a hill before dark!
Winkeladvokat wrote:.............. we are talking a matter of grams here (difference in crankset weights is 50-100g, difference in cassette weights is 50-100g - if you get a bad combo, you're 50g worse off), this is absolutely nothing and the benefits you'll see by a tighter gear range are meaningful.
Personally, if I were building a bike with that kind of gearing, I'm pick up any decent triple and you'll be looking at around 900-1000g for the set with bb, and fit other bits to suit. Mech weights, shifter weights, it's simply not going to matter! The weight difference between 105 triple and apex is not going to be noticeable; the closer gearing on the other hand is.
