Loop tail ?

[Brizn]

Does a loop tail rear triangle (seat and chainstay= one tube, bent) have any benefit/disadvantage over frames that have individual seat and chain stay tubes joined by a dropout plate?

[fausto]

probably not other than the fact that it's probably painted turquoise and thus the best bike ever made. sure does look cool though.

[TiRyder]

probably not other than the fact that it's probably painted turquoise and thus the best bike ever made. sure does look cool though.

Nuff Said!!

[Brizn]

Hm. Thanks for the thoughtful responses. Perhaps I should've posted this on vintageBMX where maybe I would've recv'd a genuine reply from someone WHO KNOWS WHAT THEY'RE TALKING ABOUT. :rolleyes:

Anyone else have meaningful input? The WeThePeople Unified24 is a nice bike.. but has a loop tail, which i thought was odd.

[kenholmes]

all of this is very basic but...

on a mtb it could be considered a disadvantage. this would be in initally felt in ride quality and but can bee seen in strength vs. weight vs. ride quality as the tubing used would have to be some kind of straight gauge material to take the stress of bending to such a degree. 4130 aircraft tubing would be exactly the perfect material to use, and alot of bmx bikes are made out of exactly that. cheap strong, ductile, easy to source, easy to weld. the ride would be well uniform in quality, with resiliance of the seat stays matching the chain stays as they are the same thing. mechanically butting a tube to change wall thickness and ride quality and then bending it at the right point is do able but prohibitively expensive as

for a mtb it is usually the case that these wall thicknesses are slightly different if not butted either for cost savings or in order to create a specific ride to the bike (sprints like a lightning bolt is stiff chain stays with a soft feel of the road which could come from more flexible seat stays). a uniform thickness tube that would provide a stiff frame for sprinting on the road would also beat the rider up with outragousely stiff seat stays.

just take a look at the tubing diameters in the kit suggestions at the back of Henry James's price list for true temper. www.henryjames.com

Scot Nicol (ibis) also wrote a great series of articles on frame materials entitled "metallurgy for cyclists" it will go into some of these issues. if you cant find it ala google let me know and ill post a link

hope it was helpful, i didnt proofread for clarity

ken

[fausto]

Hm. Thanks for the thoughtful responses. Perhaps I should've posted this on vintageBMX where maybe I would've recv'd a genuine reply from someone WHO KNOWS WHAT THEY'RE TALKING ABOUT. :rolleyes:

Anyone else have meaningful input? The WeThePeople Unified24 is a nice bike.. but has a loop tail, which i thought was odd.


ok here's the straight dope from an engineer: it's cosmetic. they use a loop stay because it looks cool, it doesn't affect anything about the ride in the slightest.

[TiRyder]

Hm. Thanks for the thoughtful responses. Perhaps I should've posted this on vintageBMX where maybe I would've recv'd a genuine reply from someone WHO KNOWS WHAT THEY'RE TALKING ABOUT. :rolleyes:

Anyone else have meaningful input? The WeThePeople Unified24 is a nice bike.. but has a loop tail, which i thought was odd.

This ios what we were referring to:

http://www.yeticycles.com/Bikes/BikesARC.cfm

Guess you werent aware that Yeti has been doing this for decades

[Brizn]

Fair enough, my error.. I figured you were implyin' that Looped Tail = Huffy, or some such.

I had seen that on the Yeti, but had forgotten about it.. I know way-old-skool BMX bikes (Schwinn Sting, PK Ripper, some Redlines, etc) used this design, but really didn't think it was a popular choice nowadays (still isn't popular, i guess). Honestly, i don't care for the look of it.. and based on Ken's informative post, I don't think I'd prefer to ride it.

[drevil]

Yeti was the first thing that came to mind when you first asked this. I believe Mongoose also had some mountain bikes in the 90s that did the same.

Anyways, here're the articles Ken referred to:
http://spokesmanbicycles.com/page.cfm?pageID=328

[markie]

Alternatively,

The loop stay is the greatest invention ever! It is so great that everyone is going to make their bikes like that next year. The year after they will use the loop tail and elevated stays....... Then in a year or two some one will put a suspension fork on a bike. Everyone will laugh at first, but within 10 years it will be impossible to buy a quality mountain bike without a suspension fork.

Fortunately thanks to the uselessnness of "microdrive" and 9-speed, luddites will re-invent one-speed drivetrains and rigid steel bikes and then one day some bored dude on the magical invention of the inter-webnet will ask, Loop tail? And the circle of life will be complete.

[Cjones]

Mmmmm... Did someone say looptail!

The looptail was around long before Yeti ever started using it. Back in the early days of BMX almost all the bikes were looptails. Somewhere around the the late 80's/early 90's the design fell out of favor and everyone started making their frames w/o looptails.

Nowadays, a looptail is definitely considered old school and most of the "retro new school" frames (Kappa, Firemans, Azusa, and SE's retro stuff) are looptails. This is mainly because guys like me want a modern BMX bike that reminds them of the bike they rode when they were a kid.

www.kappabmx.com

www.firemansbikes.com

www.vintagebmx.com/retro/index.html

From an engineering/structural standpoint, there is a very interesting interview with Mike Devitt (of SE Racing fame) over on Vintage. About half way down there is looptail talk. He says "It was an inexpensive way to build a rear end."

http://www.vintagebmx.com/interview_devitt.htm

That WeThePeople bike is pretty cool. In addition to the looptail, the headtube gussett reminds me of an old National Pro.

[kenholmes]

From an engineering/structural standpoint, there is a very interesting interview with Mike Devitt (of SE Racing fame) over on Vintage. About half way down there is looptail talk. He says "It was an inexpensive way to build a rear end."


yessss... that is exactly my point, easy to make when you dont have to consider butting the tubes. if anyone has ever actually tried to build a rear triangle in a consistent fashion and get it right every time with changing materials and designs knows that this is a real pain in the butt. and when time is money if you can simply bend some tube in a consistent manner, and any redneck with stock car aspirations can (im not commenting on mike), a rear triangle becomes easy.

now i gotta get a tube bender