frame strength?

for trials unis, does the strength need to be, like, super, or just ok?

i got this question in my head when i watched defect for the millionth time, and noticed yet another something i hadn’t before. Nik Caffroy’s frame looks sorta like an old schwinn frame… i dunno if it is or not, i’m just wondering about how much the strength of the frame effects the “trial-ability” (i can make up words if i want to) of the entire unicycle itself.

Depends on your technique…if you do all Seat-out trials stuff…no, not really at all.
If you land tall drops with your weight on the seat, then it’s a bit more important, but you’d probably break your seatpost first (like in Universe2)
I think Frame strength is most important for the bails when you let your uni fall down the cliff edge (Right, Frank?)

You really need to do more research on these topics. “Like super” strength is meaningless. You haven’t defined what axis, what forced, or what exactly “like super” strength is. Can I reccomend you do some research on basic mechanical engineering and apply it to unicycles?

In short, if you have to ask that question, no. If you’re engineering a frame for Ryan Atkins, yes. But there’s different types of strong, and a frame can be amazingly strong in some areas and pitifully weak in others. Can you pull a frame apart vertically? Can you twist it until it hits the tire? You get the idea…

Yeah that is a schwinn frame, with cotterless hub, 2 left bicycle euro cranks and 2 left primo pedals, he does use a cf miyata which is cool.

Nik’s cranks are bent to hell, i rode his uni the day we were all at gasworks. It was so bad that my foot was slipping off the pedal. Mike told me Nik is getting a kh hub and crankset. It will be good for him.


ok… maybe i should rephrase that question.

how strong is the original schwinn frame? what kind of stresses can it take before breaking or bending in one way or another?

i just like those frames…

Well, it was the only thing I never broke on mine…
My main concern was not so much the frame breaking, but that the bearing might pop out. Never happened to me, though.
If you bailed and landed on the side of the frame, I could see it bending very easily, though.

Schwinn frames are pretty resiliant. That means they’re strong, but they’re also flexible. How much flex do you want in your frame?

The smaller the wheel, the better-suited a Schwinn-type frame is to hold it. As the wheels get bigger, it gets easier and easier for the tire to scrape the sides. My 45" big wheel has a Schwinn-type frame, and it acts like a parallelogram in flex.

Consider also that a Schwinn (or Semcycle Deluxe) frame has very limited freedom of adjustment on seat height. The standard posts have holes every 1".

I think one of the reasons old Schwinns can take such a beating is because they can flex, which keeps them from denting, breaking or bending as easily. A tubular frame will dent while a Schwinn frame will just go “boing.” And stay heavy like the nearly-1/8" thick hunk of steel it is.

I would venture to say that the Schwinn-type frame is not the best kind for any type of high-end unicycling. It is best suited to a strong, easy-to-manufacture unicycle for general use. And easy as it is to manufacture, it should be a lot cheaper!

I never heard of a Schwinn bearing popping out. They used to slide around on the axles, but the bearings were very secure in the frames.

thank you, john. you answered my question EXACTLY. i was hoping to use it as a 20" trials uni. how big of a tire can these fit?

They can fit 2.5" tires, that’s not the problem. They are stupid heavy, use drilled seatposts, and have esoteric bearings. More trouble than they’re worth, better to just get a yuni.

Nik loves his schwinn frame. so much, that he wants me to modify the bearing holder design so when he gets a kh hub, the bearings will bolt up to it. the frame does flex like none other, but I’m not sure that is a bad thing. it will flex instead of bending like yuni frames do. the flex is not really noticable while riding, and won’t flex far enough for the tire to rub (while riding).

I think the schwinn frame isn’t as heavy as it seems. If anyone is interested, I’ll weigh it when i get it from Nik

In the fall section of UNiVERsE, there is a night shot of adam falling on a crank stall, and the uni snaps back up on the rail. there is no “carnage” shot of the frame, but that fall bent the bearing hole enough to ruin that blade.

if for no other reason, there is only one bolt to undo when you want to change a flat.

that’d be good if I could get the weight. i want to see how well these work for myself… i’ve been looking at a cheapie on ebay that i might want to toughen up a bit with a new wheelset…

that is the problem, you won’t be able to go splined without metalwork.

Re: frame strength?

On Fri, 11 Nov 2005 00:44:39 -0600, onetrack wrote:

>if for no other reason, there is only one bolt to undo when you want to
>change a flat.

The nice thing about the Schwinn design is that you have to undo only
one bolt to change a tyre anyway. If you remove the seat post, the
frame falls apart in two halves, letting the tyre out.

Klaas Bil - Newsgroup Addict

“erectile function trumps public image - David Stone, commenting on the importance of seat comfort”

frame strenght dsoent rlly mahter …

Of course it does, you’ve just never ridden a frame weak enough for it be a problem.

Re: frame strength?

On Sat, 12 Nov 2005 04:08:34 -0600, kington99 wrote:

>Of course it does, you’ve just never ridden a frame weak enough for it
>be a problem.

Maxisback probably meant to say “Generally, frame strength is not an
issue”. Which is true.

Klaas Bil - Newsgroup Addict

“erectile function trumps public image - David Stone, commenting on the importance of seat comfort”