The cog on the Torker giraffe is just stamped steel. It’s nowhere near Campy or Surly quality. Think Wal-Mart quality and you’re in the ballpark.
There are pictures of the Torker giraffe here
There are some spacers between the lockring and the cog. I don’t know what’s up with that.
The problem we have with the cog coming loose on the giraffes is likely due to poor component quality. I don’t have any confidence that the threads on the cog are carefully machined or held to a tight tolerance. The hub may be of OK quality, but put a cheap cog and cheap lockring on it and the combination is not so good. That may be why we have problems with slipping cogs. We don’t get Surly or Phil Wood or Campy quality in our giraffe components.
I like what I’ve read about the development of the bolt-on cog, secure yet removable, a perfect solution. Another point to add to John’s comparison to track riders, I was thinking that even the strongest track rider my not apply the amount of torque (165mm crank to a 700cm wheel), as that of a 20” wheeled giraffe. Obviously, a track bike is geared more than a tad higher than a giraffe. I think that John is correct. Even a non-athletic giraffe rider will apply more torque than a track rider. (On the other hand, have you seen those tree-trunks coming out of the shorts of some of those riders? Yikes!)
Thanks for the link to the photos. I fully agree with your assessment.
There should only be metal to metal contact. The photo shows paint on the cog. Having this spongy material between the cog and the locknut is just wrong.
The lockring appears to be a complex shape in the photo. I can’t tell if those are washers or the actual lockring, with the visible part of the lockring just a fitting for the spanner. If those really are spacers then I’m totally baffled.
The lockring threads are showing. Yiiikes!!
K-mart quality is unsafe at any speed. I wouldn’t ride it without modification.
Tmornstar: It doesn’t matter how the torque is applied to the cog, the limiting factor is wheel slip. When the tire is near the limit of adhesion then the cog is putting the maximum torque the wheel can sustain into the hub.
Yeah, those guys have big legs. They’re typical “track beasts” - fast-twitch guys who hang out in weight rooms and can sprint up to 45 mph for 10 seconds. The other kind of track rider, fast roadies that look almost normal, can’t go as fast but they can sustain 30+ mph for 5-10 minutes at a time. In either case, human muscles aren’t strong enough to spin fast rolling tires past the limit of adhesion. (I’ve heard track beasts “burn rubber” at up to 40 mph, but they were cheating because the violence of their sprint was unweighting the rear wheel. The faster guys are virtually silent because they know how to keep the tire down.)
Decelerating can slide the wheel at any speed because the rider can “lock up” his legs. Since trackies are tied down on their pedals they can resist with both legs - the back foot pushing down and the front foot pulling up.
The equivalent idea in this forum is crank bending. How many people could bend a set of cranks with muscle power alone? No one, not even the track beasts. Yet teenagers in this forum are routinely bending cranks by landing big drops. Ditto for skidding bikes.
>Tmorningstar: It doesn’t matter how the torque is applied to the cog,
>the limiting factor is wheel slip. When the tire is near the limit of
>adhesion then the cog is putting the maximum torque the wheel can
>sustain into the hub.
I may have missed it (I haven’t read too thoroughly) but don’t forget
to take wheel diameter into account. Giraffe wheel is probably
smaller.
Klaas Bil - Newsgroup Addict
“Friends don’t let friends drop to flat - Kris Holm, discussing large drops to flat ground.”
cyber mentioned that a few posts up, Klaas. As well, the pressure on the surface is important. Remember that the frictional force is dependent on the properties of the tire and of the surface, and also the pressure on that surface. Exiting a sideride, a giraffe move mentioned above, would result in a significant downwards pressure on the wheel (especially in comparison with a bicycle stop) which increases the torque on the cog while simultaneously decreasing the tire’s tendency to slip on the surface.
Re: Anyone try a Torker giraffe yet? why so cheap?
I’m opposed to welding the cog to the hub because it’s interesting to try
out different cogs. I don’t much like a giraffe that has a 1-1 gear ratio
because I feel like I’m moving in slow motion up there.
My 6-footer has 20 teeth on top and 17 on the bottom, with a 20" wheel.
Effectively a 23.5 inch.
My 4.5-footer has 20 teeth on top and 18 on the bottom, with a 24" wheel.
Effectively a 26.5 inch.
Both configurations feel pretty sweet, though a fall from the 24" giraffe
“at speed” is not pleasant.
Another issue is if you have to replace a spoke, you’re going to want to
take the cog off. Maybe you can fiddle a single spoke through if you have
to. But what if you want to replace the whole rim?
I hesitate to contradict the more experienced voices in this thread but it
seems to me that a reverse-threaded lockring is pretty safe. As long as the
lockring is tight against the cog it isn’t going to come loose all at once.
At first you will just notice some extra slop when it starts to come loose.
Of course if the lockring manages to work itself loose while the cog is
still tight, then the cog could come loose catastrophically. I’m can’t think
why that would happen, but if you were worried about it, I would recommend
visually inspecting it frequently.
On mine I have to get the chain out of the way to tighten the lockring, so
it isn’t practical to snug it up before each ride. Not that I would bother
anyway. The tightening notches in the lockring are easily damaged.
I suppose there are ways to weld the cog to the hub that would allow removal
of the cog if necessary. Maybe just weld in a few spots. Then you could
grind the weld out if necessary.
I don’t know any web vids, but you can see it in OWNL and on Unizaba. It’s basically having your whole body on one side of the unicycle, facing forwards. You pedal with the foot nearest the uni and support your weight with your hands on the seat. The other leg flies around in the air keeping your balance. I can’t do it… yet…
I agree with Mark. Perhaps the standard track hub locking ring is not the perfect approach, but it should be possible to redo the wheel without a grinding machine, but still maintain a secure attachment. It also should be possible to continue to leech off the bicycling world and use a standard track hub; perhaps we need to come up with our own locking mechanism.
There aren’t very many online photos or videos of the side ride. Klaas has a short QuickTime video of Sem Abrahams doing a side ride. Klaas’ Sem videos
Now imagine doing that on a 6’ giraffe and transitioning in and out of the side ride. It’s amazing. And Dustin makes it look so smooth. The side ride is the main skill, but it’s the transition in and out of it that is the really impressive part.
Back to the original question about the quality of the Torker Giraffe.
I took another look at two assembled unis. Both had a definite “loose” and “tight” spot in the chain as the crank does a full revolution. It appears the lower cog is slightly off center, probably less than 1 mm. It is not uncommon to have somewhat of a tight spot but I found this greater than other giraffes. The chains weren’t tensioned very much so there was quite a bit of slack at the loose spot.
Also, at the bottom of the frame, where the frame legs are pinched down by axle, a separate piece of metal is welded into the frame. You can see it in the profile pic and lower bracket pic . On other giraffes I have seen (Schwinn, TUF, Matthews, Savage) the entire lower frame leg is pinched flat and a groove is cut for the axle like on the Schwinn here. This may not be a bad thing, but it is different than most other giraffe designs.
My opinion so far is the Torker is a medium quality giraffe. Probably fine for light riders but before I would put someone big on it or consider it heavy duty I would want to know more about the sprocket attachment and how the stamped steel componets are going to hold up.
Maybe Uni.com can take one of the sprockets apart when their shipment comes in and give us a report for the good of the order.
Track bikes don’t use these things because at the end of the stays there is a honking big slab of metal for the track nuts to bite into - it’s usualy a slab of steel about an 1/8" thick. Those presed stay ends look really flimsy to me. I doubt they would survive the kind of tightening a track bike regularly endures.
hey im buildin another giraffe at the moment u remember my 7 ft 26 inch wheeled giraffe im buildin one i think its close to 8ft and using a 26 2.4 inch wide downhill tyre and disc hub im bolting a sprocket to the hub just got to find a small 28t or make a washer will have pictures of it up next week sometime when its all painted its gonna be bright pink and yellow
I’m pretty big and I have yet to bend mine. Only trouble I’ve had is the sprocket coming loose on the wheel but this can be easily fixed. Start to mess around on them and you will bend the frame and the wheel axle fairly easily, as a much lighter friend of mine can attest.
That’s too bad if Torker is still using a screw-on cog that can unscrew. As Kington mentioned, you often get a warning when this is starting to happen when you feel some slip. If you stop riding immediately you won’t get hurt. If you’re not paying attention, or otherwise occupied such as being in the middle of a show, it can fail the rest of the way with possible bone breakage.
This seems like a good thread to add this:
I think a screw-on cog can work fine with a little modification. All it needs is a notch or something other than a round hole where it attaches. If there are a few bumps or keyways in the cog/hub interface, a lockring should hold it on just fine and it should never slip. Just check the lockring from time to time for tightness. I would still use Loctite on it to be sure, though maybe not the hard-to-break red kind.
I was talking to my friend Bounce a few months ago, he was one of the more successful juggler-uni performers in the 70’s-90’s on Key West Pier.
I was riding by on my 36 and we started talking, and he lead me back to a shed, and showed me a 42" uni with an air tire he bought when his troupe was touring in Japan a long time ago.
I asked if he had been riding much lately, and he said no, not since his accident. He asked if I had heard about it, and pointed to the scars under both knees. Kinda embarrassed, I admitted I didn’t know about it, and sort of tried to change the subject. But not before Bounce told me how he got the scars.
He was doing a show on a Semcycle giraffe when the bottom sprocket came loose suddenly, causing him to land on both knees with such force that he could not walk for a long time, and needed surgery on both knees. He is still kinda crabby and pissed off about it.
Given the advice of the smart J’s ^ , and Bounce’s misfortune, I have decided not to buy this type of giraffe myself.
What about the dual chain Nimbus ? Does it have a different design ? Besides the weight and $ , what else sucks about 2 chains ? Am I correct in thinking 2 chains is safer ?
I know Bounce, he came to one of the big unicycle meets back in the 80s, possibly 1983 in Syracuse (USA Nationals). Also at the IJA Festival that year. He had a very cool zig-zag giraffe which I believe had a double chain that also zig-zagged along with the frame, making it very visual.
Too bad about his nasty giraffe accident. A reminder to all you giraffe riders out there (any brand) – make sure your lockrings and/or other chain parts are tight!
Double-chain giraffes:
Cool to look at; a professional and more interesting appearance.
A little more weight, but weight is mostly not an issue on giraffes.
Possible trouble keeping both chains tight due to possibly slightly off-centered cogs and/or uneven chain wear
“Backup” like a RAID 1 hard drive; one chain’s still there if the other one breaks. Not only that, both are less likely to break because they have less strain on them.
Chain grease will get on you and your car more than with one chain
I haven’t owned a dual-chain giraffe myself, but I like the way they look. The chain tightening thing is probably a very minor issue unless one cog is well off center. Your chain is far, far less likely to snap, but as to whether it can come lose as described above will depend on the specific build of the unicycle.
Something I believe I was told about the Semcycle giraffes many years ago (may not be accurate). I think I was told that they were built to be double-chain giraffes, and those were the top-of-the-line ones. But they were also available with a single chain for people on a budget. However The single-chain version may have had a potential for loosening (like many other giraffes) that was not present with the dual-chain ones.
Nimbus has nice chunky bolts through both chain wheels, no chance of slipping. 2 chains is theoretically safer in that if you snap a chain you don’t fall off, but the chance of snapping a chain on a giraffe is minute so it really makes no difference in that respect.