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Old 08-26-11, 09:58 AM   #1
bluefoxicy
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Is it time to retire the FDR?

For various reasons, Front Derailleurs seem to cause problems. Cross-chaining, gear overlap (to deal with cross-chaining), tuning problems, shifting problems...

What about using a 42T chain ring on every bike, and sticking a 3 speed IGH in the back? Throw a 5 speed cassette on, with spacing between the hub gears, and you can get better gear range than the typical ~14 discrete gears a triple crank system offers.

The one drawback seems to be added weight in the rear hub (unsprung, so not comparable to the reduced rear cassette, crankset and FDR weight). Additionally, on rear suspension bikes you can bounce the rear wheel due to torque applied to the axle. So some race conditions and some full suspension bikes may benefit from a FDR rather than an IGH.
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Old 08-26-11, 10:12 AM   #2
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Or you could just learn to adjust your FD.

And good luck selling road riders a system you'll break by shifting under load. IGHs don't like that.
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Old 08-26-11, 10:27 AM   #3
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You can pry my front derailler out of my cold, dead hands, or steal it off my bike but in that case I'll chase you down and beat you up
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Old 08-26-11, 10:32 AM   #4
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Or you could just learn to adjust your FD.

And good luck selling road riders a system you'll break by shifting under load. IGHs don't like that.
I thought automatic IGH systems didn't like shifting under load (turn off the auto-shifting before you stand to pedal). Shimano Alfine at least is known to shift under full load, so does SRAM's offering. As there are more, smaller gears inside these 8-9 speeds than comparable 3 speed systems, I'd assume a 3 speed IGH would have stronger gears with better contact surface area and thus more efficiency and load bearing capabilities.

My FDR doesn't seem to like shifting under load. Often the chain will fall off the bottom, somehow ... gets caught under the crank and against the frame, and I have to backpedal to fix it (?!). Not sure what that is. Probably misadjusted. It makes sense if you assume the bottom of the chain catches the chainring before the top, in which case it's being pulled by the bottom and then when the top shifts over there's a little free chain up front... but that should fix itself in a half revolution.
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Old 08-26-11, 10:34 AM   #5
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There's certainly nothing fancey about the way an FD works. But work they do. And fairly well in fact. Yes they take a bit of tuning. And yes a lot of the new shifters do not have the ability to micro trim them like they should but that's not the actual derailleur's fault. As for not dealing well with cross chaining? The chain would appreciate it if you don't cross chain anyway since it puts undue loads on the side plates and is likely one of the bigger factors that results in breaking chains during rides.

And let's not forget that IGH's are a lot more expensive than an FD and an extra chainring or two. And that if you're going to have a wide range rear derailleur that a front "guide" isn't a bad option to aid in keeping the chain on the ring anyway. It helps avoid deraillments that could occur otherwise.
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Old 08-26-11, 10:37 AM   #6
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You can pry my front derailler out of my cold, dead hands, or steal it off my bike but in that case I'll chase you down and beat you up

It'll be kind of hard to chase him down when your bike is stuck in the 24 tooth granny gear.

THe thing about derailleur systems is that you are always cross chaining to a degree... even if you only use one chainring. Each chainring only has one cog that it is perfectly aligned with and all other gears have the chain working on a angle.

Having mutiple chainrings gives you a couple of gears that are worse to use as the others, but they give you many useable options you would not have otherwise. You also get the oportunity to select a gear based on the ratio and on the chain angle... I try to keep my 10-speed cassette bike in the smallest 7 or 8 cogs while using the big ring, the largest 7 or 8 while using the small ring, and the middle 6 or 8 in the middle ring.
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Old 08-26-11, 10:39 AM   #7
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Rohloff and a Gates Carbon Belt Drive, gets rid of the FD, and gives loads or gear choices, if you have the money....
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Old 08-26-11, 10:57 AM   #8
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Rohloff and a Gates Carbon Belt Drive, gets rid of the FD, and gives loads or gear choices, if you have the money....
Rohloff and a chain does the same thing and costs slightly less money.
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Old 08-26-11, 11:18 AM   #9
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I thought automatic IGH systems didn't like shifting under load (turn off the auto-shifting before you stand to pedal). Shimano Alfine at least is known to shift under full load, so does SRAM's offering. As there are more, smaller gears inside these 8-9 speeds than comparable 3 speed systems, I'd assume a 3 speed IGH would have stronger gears with better contact surface area and thus more efficiency and load bearing capabilities.

My FDR doesn't seem to like shifting under load. Often the chain will fall off the bottom, somehow ... gets caught under the crank and against the frame, and I have to backpedal to fix it (?!). Not sure what that is. Probably misadjusted. It makes sense if you assume the bottom of the chain catches the chainring before the top, in which case it's being pulled by the bottom and then when the top shifts over there's a little free chain up front... but that should fix itself in a half revolution.
That's chain suck. You want to get rid of your FD because of a problem that will happen with or without the FD?
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Old 08-26-11, 11:25 AM   #10
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I think (and I may be wrong), that a well maintained derailleur set up is much more efficient than an IGH as there are internal losses. I never have an issue with my FD as Campag ergos allow you to tune it anyway.

As the french used to say " C'est brutale mais ca marche"
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Old 08-26-11, 11:25 AM   #11
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That's chain suck. You want to get rid of your FD because of a problem that will happen with or without the FD?
Chain suck only happens when shifting chain rings.... if you had only one chain ring, how would the chain get caught on one ring and also cross to the other ring?

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I think (and I may be wrong), that a well maintained derailleur set up is much more efficient than an IGH as there are internal losses.
96% vs 98%. Instead of going 20mph, you go 19.59mph.
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Old 08-26-11, 11:46 AM   #12
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I thought FDR died in 1945.
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Old 08-26-11, 12:17 PM   #13
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Chain suck only happens when shifting chain rings.... if you had only one chain ring, how would the chain get caught on one ring and also cross to the other ring?



96% vs 98%. Instead of going 20mph, you go 19.59mph.

That 0.41 mph makes all the difference
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Old 08-26-11, 12:31 PM   #14
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Rohloff and a chain does the same thing and costs slightly less money.
if your getting rid of the FD, may as well do away with the chain as well.
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Old 08-26-11, 12:39 PM   #15
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I'm with the OP. I think front derailleurs are a pain, and unnecessary. Adjusting them is not the problem; the hateful thing is that if you have one, you have to be shifting and 'trimming' it constantly, just to use all the gears you have in the rear. If you have it, you need it. If you don't, you don't.

I've tried 3-speed IGH and found they weren't durable, especially in the winter. Surprised? They're not really 'sealed' although many think (or thought) that they are. It's also very difficult to adjust the bearings or replace them when they fail (which they did).

I now use a single-speed chainring in front and a 7-speed freewheel in back, with a friction shifter. Simplicity is bliss.

To free yourself from the front derailleur, you first need to accept that you don't really need or want 21+ gear combinations. I find 7 are plenty, but it's even possible to run 1 x 9.

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Old 08-26-11, 01:01 PM   #16
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It'll be kind of hard to chase him down when your bike is stuck in the 24 tooth granny gear.
I run a 30 and with my properly adjusted front derailler I can use the 12T cog without chain rub after adding a little trim. 30/12 at 100rpm gets me almost to 20mph. You better be prepared to run!
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Old 08-26-11, 01:04 PM   #17
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This option has been discussed many times in BF.
SRAM's current offering=http://www.sram.com/sram/trekking-comfort/products/dual-drive-24
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Old 08-26-11, 03:14 PM   #18
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I have 2 bikes with triples, which are supposed to be the worst when it comes to adjusting. My commuter I haven't touched since the end of the winter season. I did, though, have to clean the FD on my training/race bike so that it would shift into my granny gear more easily because it had accumulated crud from riding on wet roads. It was really hard, I wiped it with a rag and it works great again.

Where are you getting the numbers for difference in efficiency, btw? If you have a chainring up front for a IGH you're at the same efficiency of a FD system, unless you are thinking a FD is always run crosschaining? That setup you'd have the "inefficiency" of both the RD and the IGH

Last edited by somedood; 08-26-11 at 03:29 PM.
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Old 08-26-11, 03:50 PM   #19
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Downtube shifters,derailer never drags.

IGH's use planetary sets to get gear ratios.....not the best way of transfering power.Loss thru friction,about 3% per stage.

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Old 08-26-11, 05:29 PM   #20
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I run a 2x9 and have never ever adjusted my front dr. I have roughly 12,000 miles on my commuter with no front derailleur issues. I don't even know what adding trim is. I suppose it took me roughly a month to learn how not to cross the chain too far, but haven't given it a second thought since then.

I have spent far more time maintaining and adjusting the geared hub on my wife's bike than either of the derailleurs on my commuter by a wide margin.
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Old 08-26-11, 05:37 PM   #21
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Or you could just learn to adjust your FD.

And good luck selling road riders a system you'll break by shifting under load. IGHs don't like that.
Never had a problem shifting under load with either of the two Nexus red band hubs I've had for a couple years. Which IGH are you using?
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Old 08-26-11, 05:53 PM   #22
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Rohloff - which seems to be regarded as the best - warns that shifting under load could cause the hub to slip into neutral instead of engaging and lead to a crash. - "Changing gears under high pressure is at the riders own risk"

And the old Sturmeys would simply refuse to shift under load at all.

Last edited by Nerull; 08-26-11 at 06:01 PM.
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Old 08-27-11, 12:59 AM   #23
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.... As there are more, smaller gears inside these 8-9 speeds than comparable 3 speed systems, I'd assume a 3 speed IGH would have stronger gears with better contact surface area and thus more efficiency and load bearing capabilities.
IME - No. Design goes like this:
- How much torque will the average rider produce?
- what dimensions do we need to deal with that?
- will there be any particular production costs associated with that size, i.e. will making the parts bigger be cheaper?

So while a S-A 3-speed is a tad chunkier than (old) Shimano 3-speed, cog widths and axle diameters remain pretty much the same as far up to 8-speed at least.

A 3-speed can be a tad more efficient, simply because(depending on gear) it can have fewer parts "on-line" in the power train. Higher quality offerings tries to combat that by building to finer tolerances and better surface treatments.
Not that one couldn't be built though. I believe the S-A 3-speed fixed use quite chunkier cogs and axles as compared to the regular models.
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Old 08-27-11, 08:35 AM   #24
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Operator error is the cause...cross chin is not caused by the FD,
except that with just one chainring it's in the center.
cross chain is the chain running a Z bend around the outer most position and the inner most.
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Old 08-27-11, 12:17 PM   #25
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Operator made an error? He won't want to hear that!
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