Talk:Shaft-driven bicycle

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Engineering

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Efficiency[edit]

Shaft drive is 5% less efficient - but is this under optimal or real-world conditions? My chain bike ends up not being oiled often enough and probably looses efficiency quite quickly. Is there any data on real-world comparison of efficiency? Actual links to measurements would be fantastic. —Preceding unsigned comment added by Roboconnell (talk • contribs) 21:50, 31 October 2007 (UTC)[reply]

A bicycle chain can be very efficient: one study reported efficiencies as high as 98.6%.^[1] Efficiency was not greatly affected by the state of lubrication, the report's authors stating: "The role of the lubricant, as far as we can tell, is to take up space so that dirt doesn't get into the chain".^[1] A larger sprocket will give a more efficient drive, reducing the movement angle of the links. Higher chain tension was found to be more efficient: "This is actually not in the direction you'd expect, based simply on friction".^[1]

^ ^a ^b ^c Spicer, James (1999-08-19). "Pedal Power Probe Shows Bicycles Waste Little Energy". Retrieved 2008-02-13.

Manufacturers[edit]

Just curious but what is wrong with posting manufacturer links? It seems stupid not erase them. —The preceding unsigned comment was added by 66.3.84.36 (talk • contribs) .

Please see WP:EL for external links guidelines and WP:NOT a web directory. --GraemeL ^(talk) 00:30, 27 June 2006 (UTC)[reply]

Both of those guidelines, as well as other articles, imply that having manufacturer links is okay. Wikipedia is not a web directory, but when there are maybe 2 major chainless bicycle manufacturers, and a tiny number of smaller ones, omitting them seems like a major omission. --151.203.253.181 00:00, 28 February 2007 (UTC)[reply]

I agree. I just ordered a Dynamic bicycle and had to search through the old edits to find the URL. So I re-inserted it. I think it is a service to provide this link. Jeff dean 00:07, 27 April 2007 (UTC)[reply]

Torque units[edit]

Torque is not lb/ft but ft*lbf, aka "pound-feet." See http://en.wikipedia.org/wiki/Torque for details. —Preceding unsigned comment added by 136.160.250.253 (talk) 21:05, 29 July 2008 (UTC)[reply]

Advantages and disadvantages[edit]

On 07:25, 24 June 2006 Sheldon Brown added this to the article:

Most of the advantages touted by proponents of shaft drive are only advantages compared with open-chain, derailer gear systems. Many proponents of shaft drive use specious (if not dishonest) arguments "comparing" shaft drive systems with derailer gear systems. Any such comparisons are meaningless, it's like comparing apples and locomotives.
A valid comparison of shaft vs. chain drives can only be made if both bikes use the same type of gearing, whether singles-speed or with an internal gear system.
These same advantages can be obtained with chain drive using a fully-enclosing chain case, as with old English roadsters and many current Dutch bikes.
Shaft drive proponents also often compare sealed, enclosed shaft drive systems with open, exposed chain drive systems. This is also a misleading comparison. Most of the advantages claimed for shaft drive can be realized by the use of a chain case.

While this was unsourced and really belonged here on the talk page, I think he had a point, and so I've posted it here now. I hope in the near future, unless someone beats me to it, to find a decent source and tackle the issue. -AndrewDressel (talk) 03:03, 24 September 2009 (UTC)[reply]

It's certainly nice to be clear regarding feasible and available construction of each, but I see no problem comparing the majority type of chain-driven system (which is clearly open-chain with dérailleur, unless Nederland has greatly increased in size recently, no?) with the majority type of shaft-driven system. There must of course be sources regardless. ¦ Reisio (talk) 03:29, 24 September 2009 (UTC)[reply]

*Suitability to longer drive trains: The shaft-driven system is particularly suitable to many recumbent applications where there is a long distance from the crankset to the driven rear wheel. Maintaining chain tension is often difficult for these applications. Also, the chain line may not be straight, necessitating the use of extra jockey wheels. A drive shaft can relatively easily turn through these slight angles with the use of a universal joint.

Has anyone even brought such a thing to market so that this point can be verified? There are dozens of chain-driven recumbents in production that have no trouble maintaining chain tension. Even if they do not use derailleur gears, a simple singulator will do the job. Can anyone verify that adding a universal joint is cheaper, lighter, or more robust than a jockey wheel? A google search reveals only a single home-built shaft-drive recumbent. If shafts are so great, why are there not more? -AndrewDressel (talk) 16:16, 24 September 2009 (UTC)[reply]

Never seen a car? ¦ Reisio (talk) 14:12, 25 September 2009 (UTC)[reply]

Yes, I have seen a car or two. In fact, I'm familiar enough with them and bikes to know full-well that success of a technology on one platform does not guarantee success or even suitability on another. So, unless we can find an example that clearly proves suitability, by success in the market place for example, or an established expert that has written about such suitability, this article is better off without the conjecture. -AndrewDressel (talk) 14:54, 25 September 2009 (UTC)[reply]

These claims need citations which support them. "Power loss" and "torque" had citations (1 and 2) which refute their claims. http://www.jhu.edu/news_info/news/home99/aug99/bike.html http://yarchive.net/bike/shaft_drive.html Auldeskuule (talk) 04:32, 7 December 2009 (UTC)[reply]

The drive shaft and bevel gears take up less volume in a shaft drive than an enclosed chain; this makes for a compact mechanism, and the additional ground clearance may benefit riders on rough terrain.^{[citation needed]} Is anyone seriously marketing shaft drive for off-road? Otherwise, I can see no benefit to additional ground clearance. -AndrewDressel (talk) 14:53, 2 March 2010 (UTC)[reply]

A quick look at the Dynamic Bicycle web page (that someone linked above) shows that yes, someone is marketing an off road bicycle that is shaft driven. Merpius (talk) 20:35, 4 November 2010 (UTC)[reply]

Shaft drives are less susceptible to damage.^{[citation needed]}

Maintenance is also safer as there is no danger of clothing or fingers being drawn into the enclosed gears, and cleaner as enclosed gears cannot get grease on hands or clothing.^{[citation needed]} What maintenance is being done without opening the gear enclosure and thereby exposing clothing and fingers into the gears? -AndrewDressel (talk) 14:53, 2 March 2010 (UTC)[reply]

I'm not sure about other manufacturers, but after a look at Dynamic Bicycles, you can grease the bevel gears/shaft using a specialized grease gun without dis-assembly. Also, no dis-assembly of the drive system is necessary to do maintenance of many other parts of the bike, during which you could come into contact with the drive assembly; since this is sealed it wouldn't get any grease on you, whereas an unsealed type possibly/probably would. Merpius (talk) 20:35, 4 November 2010 (UTC)[reply]

Though the shaft-driven system seems simple on the outside, the manufacture of the necessary bevel gears is complex compared to that of a chain and sprockets.^{[citation needed]}

A shaft-driven system is less efficient than a chain-driven system. Shaft driven systems are often quoted as being "95% efficient", while chain driven systems are quoted as "98% efficient".^[1]^{[failed verification]} Bicycles typically employ more torque (an adult man can easily generate more than 100 ft-lb) but at much lower rotational speed than many motorcycles and cars.^[2]^{[failed verification]} This mitigates against shaft drive as the shafts must be large to cope with the torque, which adds to their mass. This is particularly noticeable when pedaling hard, when there can be noticeable torsional springing in the drive train.

References

^ Spicer, James (1999-08-19). "Pedal Power Probe Shows Bicycles Waste Little Energy". Retrieved 2008-02-13.
^ Jobst Brandt (5 Oct 1998). "Shaft drive". Norman Yarvin. Retrieved 2010-02-18. Torque on a bicycle is higher than most automobile engines while the rotational speed is about 100 times lower.

Internal Gear Hub not required?[edit]

The CeramicSpeed Driven drivetrain has a different mechanism for shifting than an internal gear hub. Though I have no idea how viable it really is, because I haven't even been able to find videos of someone actually shifting the thing. — Preceding unsigned comment added by 70.124.165.8 (talk) 20:41, 12 July 2018 (UTC)[reply]

It does. As far as I can make out, the bevel at the back of the shaft moves between the concentric rings with which it engages. If it's real, it's fiendishly cunning. However, it is a bevel drive (albeit it may be more efficient), and WP:CRYSTAL; if these start turning up in actual bikes, and independent sources report on them, then we can write about them. Pinkbeast (talk) 21:49, 12 July 2018 (UTC)[reply]

It's a hideous thing, the sort of thing a first year mech eng student invents out of eBay and their first CNC mill. It's not a bevel gear, more of a face gear. Like most such, it avoids the sliding friction and thus the losses of a bevel gear, but it also reduces to a near-point contact and so is extremely weak. There are only about two teeth in contact at a time, and they're of negligible width. The cheap unshielded ballraces would be an issue too, but they're going to outlive the driven gear. Andy Dingley (talk) 21:59, 12 July 2018 (UTC)[reply]

[Spicer-1] Spicer, James (1999-08-19). "Pedal Power Probe Shows Bicycles Waste Little Energy". Retrieved 2008-02-13.

[Spicer-2] Spicer, James (1999-08-19). "Pedal Power Probe Shows Bicycles Waste Little Energy". Retrieved 2008-02-13.

[3] Jobst Brandt (5 Oct 1998). "Shaft drive". Norman Yarvin. Retrieved 2010-02-18. Torque on a bicycle is higher than most automobile engines while the rotational speed is about 100 times lower.

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