Originally Posted by bjkeen
Eyeballing the thicker and more heavily built nature of a single sprocket, and the lack of fancypants shaping of the teeth, and that the chain isn't walking over them, ever, suggests to me that the advantage here lays with the single sprocket. It's worth putting some thought into the mechanism of chain and cog wear. Having a straight chainline (and a beefier chain to begin with) is to the benefit of all of these things.
Well, just went out in our yard with my digital caliper and made some measurements:
On a "Kildemoes Logic" bike with a Shimano Nexus 8 hub (SG8R20 Rollerbrake) the rear sprocket was 2,5mm thick at base. The teeths became progressively thinner at the edges, just like on any track- rear sprocket I ever saw (Miche, Shimano, Surley), just like on a cassette.
On my own 9-speed cassette the largest rear sprocket measured 2.0 mm. It too became thinner at the edges.
On an old noname bike with a Shimano Inter-4 gear hub, the rear sprocket measured 3.0 mm. The sprocket became thinner at the edges, but not as much as the other two.
So some real world examples shows sprocket thickness varying between 22% and 33% thicker than my cassette, even considering the ramping grooves, it really isn't that much of a difference, but for arguments sake let me say that +50% more thickness equals 50% longer wear (linear). That means that if I spread the wear on my cassette to only 3 rear sprockets I would still be significantly ahead considering wear.
I really don't think that a cheap BMX-style sprocket is made of the same grade of steel as a Shimano 105 cassette, and steel quality (hardness) plays a role in how fast things wear out.
Originally Posted by bjkeen
I don't have a hard time believing it at all and I'm going to find out. The way to decide would be to find out how often single-speed riders have to change their chain and cog.
Please notice point 6 here:
http://www.surlybikes.com/spew3.html
If they don't use real fixie hubs, they may need to change their chains and sprockets very often, which skewer the result to the advantage of cassettes.
I claim around 5-7.000 miles before a maintainend cassette wears out, when used by a roadie.
Originally Posted by bjkeen
You mean that the police will get upset if I have a triple on the front and a internally geared hub on the rear? Of course, it's kind of unneccessary to do such a thing, since you don't really need the extra gearing range..
The police would wonder how you managed to change gears in front since you wouldn't have something to change chain tension with (like a derailleur). A further 3. degree interrogation would probably make you confess, that even if you could make this arrangement work, all you managed to to was to underscore the point, that in order for a internal gear hub to get more gears is, ta-da!, to turn it into a derailleur system.
Originally Posted by bjkeen
Well, you'd have to get an 11-34 cassette, for one, and a different rear derailer to match. And you're comparing a full service retail type of price with a deep discount price. Furthermore, the difference in chain saves you about $10 as well. I think it's about a wash, or even a slight advantage to the hub system.
I do think remember writing, that people ought spec the stuff at their own favorite LBS. Long discussions ensue, but the end result is, that I could spec something really good, much cheaper than an internal hub, so can anybody else trying.
Originally Posted by bjkeen
Does a grip shifter on a rear derailer work as nicely as the grip shifter shifts the Nexus? I don't know, because my bike isn't finished yet, but I'll find out. It's not like it's hard for me to do the usual lift the wheel shift the gear gyrations at a stop sign; I do that now, but I'm looking forward to not having to worry about that.
Well, the grip-shifters probably works as well with derailleurs as with internal gear hubs, since the perform the exactly same operation: move a cable a certain distance, then stop and lock. But does grip-shifters work as well a triggershifters? Perhaps a matter of personal preference, but not a choice to make with a Nexus 8 hub.
Originally Posted by bjkeen
I don't think there are too many people who would have too much trouble arguing any of these points.
Actually people have real problems arguing my points, weight, price, friction, number of gears, the wide variety of shifter options, riding positions (bars), ease of maintenance (eg. QR's versus nuts).
Let me try to explain what puzzles me:
I have no problem understanding, that weight may not be as important as other factors. So an argument that goes like this:
"I choose heavy tires(disadvantage) to gain less punctures(advantage)."
"I choose a heavy saddle(disadvantage) for more comfort(advantage)."
"I choose light and supple racing tires(advantage) even though I may puncture more (disadvantage)."
So normal choices are often trade-off choice. You consider disadvantages and advantages of something.
I it is just that when I consider the trade-offs and gains by choosing a internal gear hub, I just can't find significant advantages by choosing a internal gear hub, that isn't based based on myths (maintenance etc).
Try to fill out the advantage part in the sentence below:
"I choose a heavy, expensive, high friction (disadvantages) internal gear hub to gain ...(advantages)."
In have no problem saying: "I like X because it is pretty, then I don't care about any other disadvantages there may be."
(aesthetic reasons can be considered and advantage)
Originally Posted by bjkeen
I'm going to find out. It would help if you compared with bits more actually comparable. I don't think it's cheaper. So, well, you're convincing to yourself, but not to other people, which is fine.
Hub:
Shimano Tiagra FH-4400 Rear Hub – 8/9 $19.95
Shimano Deore LX Freehub 8/9 Spd $29.95 426g
Shimano Ultgera 6600 10 speed Rear Hub $79.99 407g
Derailleur:
Shimano Deore RD-M530 Rear Derailleur $39.95
Shimano 105 RD-5600 SS 10-Speed Short Cage Rear Derailleur $67.99 232 grams.
Cassette:
Shimano 105 HG70 9spd Cassette $29.95 247g
Sram PG-970 9 Speed ATB Cassette $34.95 340g
Light but expensive:
$80+$68+$30 =$178
407g+232g+247g=886g (including skewer)
Cheap:
$20+$40+$30=$90
Internal: Shimano Nexus 8 Premium SG-8R25 $199.99 1550 g (probably without nuts and axle)
Still don't think that a quality derailleur option is both cheaper and lighter? Don't live in denial.
Do you own comparisons, check out the prices where you would like to buy, check out other solutions, like the praised SRAM X-series.
Originally Posted by bjkeen
I'll grant you on weight and friction, but these are marginal (300grams, 4%) especially considering what these kinds of bikes are for. Durability under appropriate maintenance is a wash, but I think that maintenance is less for the internally geared hub; I'm expecting to have to repack it once every 10k miles or so, and will never need to do other adjustments.
You may disregard 600g as nothing important, others may disagree, but I am still puzzled what one gains by choosing an internal hub. About maintenance, I have stated my case in other posts; a squirt of oil on the derailleur once in a while is all the maintenance that is needed. Easy to do, no need to do disassemble anything. What about the gears inside the internal gear hub, do they need grease too? Yes they do, but that is a much more complicated operation, requirering a disassembling of the hub. Hey, I really don't think it is a problem, it is a cheap thing to get done at the LBS, a yearly inspection of bearings etc. is a good idea to do, no matter what kind of gearing system, but I honestly don't think that internal gear hubs on bikes that are actually used are any less maintenance intensive than a derailleur system.
Originally Posted by bjkeen
In terms of likelihood of being damaged as a result of some mishap, the internally geared hub absolutely wins hands down.
Yes, true. A genuine advantage of an internal gear hub. On the other hand, internal gear hubs actually gets destroyed too. I really wish I had a digital camera, so I could show my collection of broken internal gear hubs; Shimano Inter 4. and Inter 7, and SRAM S7. All bearings was of course in a horrible condition. The Inter 4 is probably broken in the inside, since it gets stuck when turned, crunchy, gritty feeling with lots of resistance when turning. The Inter 7 lacks a metal part on the drive side. The snapped of edge is visible, but I really don't know what action the missing part performed. The hub was discarded with an otherwise working bike (cheap model though, with one of those horrible cheap front suspension systems). The bearings are in a horrible condition, since it feels gritty and uneven to turn. The SRAM S7. Don't know exactly what was wrong. The owner had tried to repair it by disassembling it, couldn't fix it, and discarded the parts taken of, before discarding the entire bike. (low end but nice MTB wo. susp.).
Perhaps some of these hubs could be repaired, but labor wages often makes such repairs difficult to perform cheap enough.
So if a rear derailleur snaps, I am down $40-$70, but if a internal gear hub brakes, I am down $150-$200 plus a wheel rebuild, or rims+spokes, lets say $235 for a wheel with a cheap rim.
Originally Posted by bjkeen
Basically, these things exist for a reason, not out of some sort of conspiracy or consumer stupidity or fear. The things you think are important in a shifting system are best satisfied with a derailer but other people have different priorities. The clue as to where these priorities are different are where you've had to stretch your reasoning.
I really think that a lot of people are assuming a lot of myths regarding both derailleur systems and internal gear hubs, and therefore makes their priorities on false premises.
I am not saying that internal gear hubs are bad, they perform adequately for some people as long as they are maintained.
Well, I think I have said what I wanted to say about internal gear hubs in this discussion, and probably won't post more in this thread. However, a thanks to you and everybody else in this thread, in trying to keep this a nice and civilized discussion, it has been enjoyable.
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Regards