Talk:Hub gear

Image

Not having understood too much about hub/epicyclic gears until today, I'd appreciate some feedback on the diagram I've added. As I understand it, there are several different ways of driving the gearing system, involving various configurations of fixed parts and movable parts. Some that I looked at had a fixed sun gear, and movable planetary gear holder that provided the input rotation; I don't know which is more common.

A good explanation of how gearing ratios are determined in this sytem would be nice to have! Also, if anyone can point me to some good diagrams of how an epicyclic gearbox or transmission (with multiple ratios) works, I can think about making a diagram of that too. -- Wapcaplet 03:25, 14 Nov 2003 (UTC)

Unfortunately this shows a turning sun gear - in all bicycle gear hubs, the sun stays still (being keyed to the axle) while the gear ring and planet cage rotate. —Preceding unsigned comment added by 62.249.214.190 (talk) 18:23, 21 November 2008 (UTC)

A better diagram wanted but it must be copy-right free. MalcolmMcDonald (talk) 19:17, 3 February 2010 (UTC)

I believe this is finally sorted out according to the description given by Sheldon Brown. -AndrewDressel (talk) 15:41, 21 November 2011 (UTC)

hub gear?

Should this article be hub gear? Kingturtle 05:05, 15 Nov 2003 (UTC)

Possibly, though maybe a better name would be epicyclic gear or epicyclic gearing. Feel free to move it :-) -- Wapcaplet 06:25, 15 Nov 2003 (UTC)

The article is about cycling hubs in particular, so I wouldn't call it "epicyclic" because few cyclists refer to it that way. geared hub or internally geared hub would make more sense to me. At some point it may make sense to put the technical details under one of the epicyclic suggestions and reference it from the hub article which might contain more cycling-specific and historic info AHands 12:39, 15 Nov 2003 (UTC)

Nice graphics by the way! What do you use for the 3d modeling?

Thanks! A distinction between epicyclic gearing in general and cycling hubs in particular would be good to have. I'm tending more towards explaining epicyclic gearing in general, so maybe we need a new article. The models are made in Blender. I've made an animation for the latest one, but unfortunately there are some limitations at present on size and video format for Wikipedia, so those probably won't be useful any time soon.

I'm working on finding some good explanations of how gear changes are effected in hub gears for bicycles. So far, I've found some very complex diagrams, which don't do much by way of explanation, some explanation without diagrams, and a few other grainy photos and generalized statements about how they work. I'm looking for something that would be relatively easy to illustrate, such as how a three-speed hub gear works. When I do figure it out, I'll make models and upload them! -- Wapcaplet 17:49, 15 Nov 2003 (UTC)

Usage in USA/UK - Continental Europe and the World

It seems rather strange to make such broad claims about the usage in different regions of the world. They should at least be substantiated by an independent source. Bfg 12:01, 5 July 2006 (UTC)

Also, first it says derailleur gears are most common in the UK and US while hub gears are more common in continental Europe. But a bit further it says derailleur gears have since the 1950's become the most common type of gear system on bicycles. But I imagine that in other parts of the world they are very uncommon. Or is it that there, no gears are the most common thing? It seems too strong a statement, so I'll tone it down a bit. DirkvdM 07:25, 2 August 2006 (UTC)

Image/Illustration

I know the cutaway image of the 14-speed hub is fantastically fascinating and beautful, but such intricate and recently developed mechanisms are almost unheard of in practice. Might it be better to find a similar image of something more illustrative of hub gears commonly used by cyclists (3-speed, probably), rather than a rather baffling mechanical curiosity? Ninly 17:31, 11 August 2006 (UTC)

Other Uses

Toyota is using an adaptation of this for its toyota prius electronic continuously variable transmission. At least the gears look similar even though the purpose and use are very different. Check out this site. [Prius\http://www.ecrostech.com/prius/original/PriusFrames.htm] - Go to Understanding -> power split device. Might deserve a mention. —The preceding unsigned comment was added by Chathu50 (talk • contribs) 09:02, 9 May 2007 (UTC).

Is a hub gear the what's on some farm and sonstruction machinery particuarly hydrosatic implements? —Preceding unsigned comment added by 67.201.136.122 (talk) 03:24, 6 October 2008 (UTC)

Confusing Advantages/disadvantages

Someone's confused the advantages/disadvantages section recently by replacing an item stating that hub gears are heavier with one stating that they are not, and that they cost around the same as derailleurs, but leaving it under Disadvantages. As it's currently worded, it's a neutral statement, and I don't know enough about gears to say whether it's right or wrong.

I think I've fixed that. Hub-gears are heavier and more expensive. MalcolmMcDonald (talk) 19:17, 3 February 2010 (UTC)

Also the below sentence asserts two completely contradictory ideas, making it impossible to determine what is and is not a disadvantage. "Hub gears with a large number of speeds are less efficient than a properly lubed and adjusted derailleur. A 3-speed hub runs at 1:1 in top gear and, when run-in and properly lubricated can match or exceed derailleur efficiency, benefiting from the lack of the derailleur's jockey wheels and from its perfect chainline. Derailleur gears are much more likely to be badly lubricated."

Is this sentence confirming or refuting the idea that hub gears are less efficient? If they are less efficient, why does it then go on to say that properly lubricated, they can match or exceed derailleur efficiency? 04:10, 3 February 2010 86.175.32.0

In general one can say that derailleurs are more efficient but that's not going to be emphasised in an article about hub-gears because it doesn't concern the cycling of most users. It might be more to significant to the users of hub-gears with large numbers of gears. With some exceptions and running conditions as mentioned. MalcolmMcDonald (talk) 19:17, 3 February 2010 (UTC)

Maximum Number of Speeds

The paragraph used to read that they are made with up so 38 speeds. I searched Google for "thirty-eight speed hub" and nothing showed up. If someone can find a citation, put it back in. But I changed it to 14, to reflect Rohloff's highest number.

Maintenance vs repair

I changed the item in the disadvantages section; I think it should really discuss to repair rather than maintenance.

As noted in the advantages section hub gears have very minimal maintenance, most are sealed for life (without even oil or grease points) and the only real maintenance you can do is adjusting and replacing the actuator cable, and possibly renewing the gear cog.

But if they fail (and that's a big 'if') you cannot easily get spares or dismantle them, and wholesale replacement is normally the only option. Whereas you can pick up individual components of a dérailleur in any decent bike shop when (not 'if') it becomes badly worn or fails.

Gear hubs aren't sealed for life, all of them can be opened and re-greased. Sturmey-Archer ones have a screw in ball bearing recess that is hard to get loose after years of use. Other brands usually use a large bearing that leaves a hole big enough to allow the internals in as a whole. Only the Rohloff hub uses press-fit bearing witch are difficult (but unnecessary, due to an alternative way of lubrication) to remove. Maintenance hardly ever happens though, because the are usually owned by people that just use them for basic transportation.

When gear hubs fail it is usually an indirect consequence of lubrication starvation. Every brand had its own flaws.

Sturmey-Archer ones usually fail due to one of the pawls losing function creating an uneven load on the system or breaking internal toothings due to incomplete engagements of the pawls. Even so, most survive this severe condition unnoticed for quite a while. Some have been known to be prone to axle breakage (they were made in the 80s and the beginning of the 90s (exact dates are hard to find) I have seen some for myself, the exact failure mechanism is unknown to me, the axles appear unaffected by corrosion).

Sachs ones are known to be quite reliable (except the Elan version, but it can be considered a one-off), most problems come from bearing rings that break after a while. Usually replacing the bearing rings with loose balls (and removing the debris) solves the problem. The grease in them can dry similar to the Sturmey-Archer ones, usually this causes internal springs to lock onto moving parts and getting jammed in the mechanism, usually just disrupting gear function. These can usually be replaced and gear function restored.

Shimano has been known for problems with the outer bearing getting contaminated with water and getting rusted and consequently pitted, even after a limited amount of time in wet environments. When detected in time this bearing can be replaced and re-greased. If not, the bearings will usually come loose of the worn bearing rings and block parts of the mechanism. The mechanism itself usually suffers little, but the bearing recesses are of little use by then and cannot be replaced in most hubs. Oil-lubrication has been recommended for these hubs by some, but to my knowledge no long term data of its workings have been published. Shimano has introduced a maintenance routine to replenish the internal grease with a special kind of maintenance oil. The recommended maintenance interval is relatively short and unknown to most repair shops, while the oil itself is quite expensive for individual use so this routine is quite unique.

Significant wear is unlikely even when lubricated only reasonably well due to the low rotational speed of bikes. Torque-induced damage is uncommon and unlikely to be caused by lack of maintenance. 82.139.114.136 (talk) 11:46, 28 June 2012 (UTC)

Back Wheel Strength?

It is my understanding that the back wheel of a single speed is considerably stronger than that of a bike with a multi-geared cassette or freewheel which is dished to one side to compensate for the size of the freewheel/cassette. (an internal gear hub only has one rear cog making it effectively the same as a single speed)

My question is, if this is true, should a sturdier back wheel be listed as an advantage? The back wheel tends to be the second most expensive part of the bike and the back wheel's ability to take more abuse makes the bike potentially more utilitarian in terms of being able to endure heavy loads and poor road conditions.

The derailleur rear wheel is both the weakest and the most vulnerable kind. Weak because the spindle is small and the spokes cannot exert much torsional stiffness (hence they get stretched slightly with each press of the pedals), weak because this wheel has to be dished much more than others and vulnerable because of the adjacent jockey wheel carrier.

Unfortunately the article is biased towards the non-engineering reader so a lot of technical detail gets lost and there is excessive mention of particular (and slightly esoteric) models coming from a single named manufacturer. It's difficult to know how to make it read better. MalcolmMcDonald (talk) 20:57, 11 December 2010 (UTC)

First, of course, if you have a reliable source for any of this, please add it. Second, if the diameter of the hub or its flanges was that much of an issue, hubs for derailleurs or their flanges would simply be larger in diameter. I looked in Jobst Brandt's book and, although he does discuss wide-flange hubs, he does not mention that they make stronger wheels. Third, I have seen several attempts to reduce dish, do not dispute that claim, and have left it in. -AndrewDressel (talk) 21:45, 11 December 2010 (UTC)

I cannot find a source for it either. I do know however the flange is usually stiffer than spokes, and when a wheel has relatively more flange it will become more so. Stiffness is desirable for efficiency reasons, but the difference is probably only important in competitive environments. I do however believe it to be sufficiently important to be mentioned so anyone can judge its relevance for himself. 82.139.114.136 (talk) 11:56, 28 June 2012 (UTC)

I don't know what I looked at last time, but this time when I checked Brandt's book, many more relevant details became apparent. It appears that I was confusing "wide hubs", i.e. hubs with more distance between their flanges, with "large-flange hubs", i.e. hubs with larger flange diameters.

1. Jobst states explicitly "the distance between flanges gives a wheel its lateral strength." "Multiple gears have crowded the flange spacing on rear wheels to a marginally acceptable width."
2. Large flanges do offer more torque stiffness, but this is only necessary on "aggressively ridden tandem"s. Small flanges are plenty stiff for even track sprinters. Jobst even elaborates "their reduction of torque-induced spoke loads might improve fatigue life slightly, However, with larger flanges the spoke angle at the rim becomes farther from perpendicular, causing spokes to bend at the nipple. This bend increases failures at the threads andprobably cancels any gains from reduced torque loads."
3. Large flanges do offer room for more spokes, such as the 48 spokes that "durable tandem wheels require."
4. Large flanges do make replacing spokes on the drive side of single-speed and fixed-gear bicycles easier: "they allow spokes to be replaced without removing the sprocket."

So, it appears that he does cover the benefits of wide hubs and the supposed benefits of "large-flange hubs", and finds the latter only useful on tandems. I'll update the article. -AndrewDressel (talk) 13:43, 28 June 2012 (UTC)

Anyone reading the article now would think it was written by a cycle-racer who thinks hub-gears are for wussies. MalcolmMcDonald (talk) 19:33, 12 December 2010 (UTC)

I don't see why. There are more than twice as many advantages listed. -AndrewDressel (talk) 21:07, 12 December 2010 (UTC)

The disadvantages are given much more detail than the advantages. MalcolmMcDonald (talk) 19:33, 12 December 2010 (UTC)

I've started to clean up the disadvantages section as well. You're welcome to help. -AndrewDressel (talk) 21:07, 12 December 2010 (UTC)

When detail is given, it's incomplete - parallel pins make for a much stronger chain than barrel-shaped ones, but it's far from obvious why that's the case.

I cannot find a source that confirms that claim. -AndrewDressel (talk) 21:07, 12 December 2010 (UTC)

The significance of changing gear when stationary is not made clear, nor is the improved reliability of the hub-gear wheel. MalcolmMcDonald (talk) 19:33, 12 December 2010 (UTC)

The significance of shifting while stationary was not sourced, and I do not find the inability to be a disadvantage. Does the significance of improved reliability really need to be explained? -AndrewDressel (talk) 21:07, 12 December 2010 (UTC)

Instead of which, we're told about 14-gear systems and belt-drives, neither of which bear any relevance to the experience of most readers. MalcolmMcDonald (talk) 19:33, 12 December 2010 (UTC)

I don't believe we know anything about the experience of most readers. All we can do is write the best article we can with the guidelines and sources available. -AndrewDressel (talk) 21:07, 12 December 2010 (UTC)

If we know nothing about the experience of most bicycle riders it must be questionable how well we can edit articles that would atract such people to read and enjoy and trust articles in the encyclopedia. MalcolmMcDonald (talk)

First, most bicycle riders and most wikipedia readers are two completely separate groups. Second, we attract people to read and enjoy and trust articles in the encyclopedia simply by writing well written and sourced articles. -AndrewDressel (talk) 14:33, 30 December 2010 (UTC)

Hub Weight Comparison (in table in section "List of multispeed hub gears")

This table contains wrong values and different configurations. No sources are indicated.

The weight of the SG-700 appears to be 1744 g Review. 1600 g was a target that was never met. The weight of the Speedhub is 1700 g in the standard configuration, and 1825 g [1] in the configuration for disc brakes.

Please correct the values, indicate the various configuration, and indicate the sources of the data. Thanks. — Preceding unsigned comment added by Bogl4712 (talk • contribs) 19:51, 14 June 2011 (UTC)

• Why is the Speedhub listed in the disc version, whereas a lighter version is available as well? Please note that some of the other hubs do not support disc brakes either.
• Why do you reference a superficial web article for the weight of the SG-700 that dates prior to the release of the SG-700, whereas better sources are available (see above)?
• Why do you state a target weight for the SG-700, whereas more accurate numbers are available?

Please stop fooling around. Bogl4712 (talk) 21:30, 14 June 2011 (UTC)

Your link/reference does not work. Do you have one that works? Keanu (talk) 21:36, 14 June 2011 (UTC)

See [2] Bogl4712 (talk) 21:49, 14 June 2011 (UTC)

Re-Organizing/ moving second paragraph in intro

Possibly move the second paragraph to Latest Developments, Hub-gears in everyday use, or History sections, it seems to be in an odd place that makes the into seem disjointed. Also adding Minneapolis (https://www.niceridemn.org) and B-Cycle locations (http://www.bcycle.com) — Preceding unsigned comment added by 71.37.226.17 (talk) 19:14, 22 June 2011 (UTC)

Simplicity of shifting

The following has been removed: "Hub gears can be simpler to use for inexperienced riders, because there is generally only a single shifter to operate and there are no overlapping gear ratios. By contrast, modern derailleur systems often have two shifters, and require some forethought to avoid problematic gear combinations." I believe this to be an advantage over front and rear derailleur geared bikes with a right and a left shifter with two operation directions each, as the rider has to operate up to four trigger shift levers with opposing gear ratio changes on the right and left side to ensure that the chainline is kept relatively level. The trigger finger typically shifts to a lower gear ratio on the left side shifter while the trigger finger shifts to a higher gear ratio on the right side shifter. It is a problem mostly with wide gear range derailleur gear systems, with two or more chainrings up front. Please help modify the above sentence so that it better explains this factor or I will simply reenter it. Keanu (talk) 11:53, 5 February 2013 (UTC)