For xmas i got a 6foot DM. At first the chain was really tight. It was ok when i was rinding it, but when i pushed it, like in the house, rit was too tight to move. All the other giraffes I’d been on had quite free chains. Anyway, i loosened off my chain, but only to find that it was too slack, and made really bad noises.
I keep changing it just a little to try and find the ‘perfect’ tension, but to not much success.
I guess ill just keep fiddling round with it, but it would be really helpful if anyone had any infomation on how tight a chain should be. Any advise would be great.
Recently, I asked the manufacturer of my giraffe the same question. He understandably warned against too much tension but volunteered the following rule of thumb: the chain should be loose enough so that it has 1cm “give” when you put a 4kg weight on it (about 3/8th of an inch at 8.8 pounds).
That sounds like very accurate advice, but it’s missing one vital piece of information. It only applies based on the length of the drivetrain (axle to axle). Longer chains should allow more give, and shorter ones less.
My nine-footer uses no idler device to help with chain tension, but I don’t ride it much and it’s as high as I would go without one. A simple form of this is to take a big chainring and just stick it in at the midpoint of the chain. This worked quite well for several riders in the Redford Township Unicycle Club when I was a member. The chainring just rotates in place, as long as it leaves enough tension in the chain.
On my Schwinn Giraffe I find it takes a bit of tweaking to get the right tension. Setting the chain tensioners is not enough. Make sure you have chain tensioners. These are the little threaded things that pull the axle down and hold it in place in relation to the bottom of the frame. You set those first, but on my Schwinn, when you tighten the axle nuts it usually makes the chain a little tighter.
So the sequence is this:
Loosen axle nuts.
Set tension by adjusting the small nuts on the tensioners, but leave a little slack for when you tighten the axle. Wheel should spin freely with a touch of sag in the chain.
Tighten axle nuts.
Check chain tension. The wheel should still spin. If you give it a push and it stops spinning instantly, it’s definitely too tight and you’re putting excessive wear on your chain. It should rotate some after you give it a push.
Repeat steps 1-4 as necessary to get a good result.
(important!) After final tightening of axle nuts, re-tighten the chain tensioner nuts so you don’t lose them.
I’ve had my original chain tensioner nuts replaced by ones with that nylon stuff inside that keeps them from unscrewing.
The above method applies to any size giraffe. The part that can’t be constant is the amount of sag or deflection to allow in the chain. This will be in proportion to the chain’s length.
On my 9’, the chain does slap against the frame some, and has taken off a lot of paint in that area. But I check it for safety before every ride, by holding onto the edge of my roof and rocking very vigorously. I try to do in my “preflight” as much force as I’d use in the heat of a parade, so if it fails it’ll hopefully happen while I’m holding onto something.
I’d been wondering how to get around the fact that axle nut tightness and chain tensioner setting are interdependent. Thanks, John. And: I appreciate you using the term “preflight”.
Yes, preflight was an homage to Fred. I wanted to mention it in th post, but didn’t want to deviate from topic. Fred took me up in a glider last summer over Lake Tahoe, the coolest aerial ride I’ve ever been on:
There is a thread HERE with a discussion of the eccentricities of the chain sprockets on some giraffes. This causes somewhat chaotic tensioning problems that can in some cases be reduced but not eliminated.
Looks like this thread is soaring off topic (pun intended). Sooner or later folks will bump into this strange picture among John’s photos. Before someone else asks what it is, I am now posing this as a question: Who can figure out what strange contrapture John is holding here?
(Above photo copyright of John Foss, you will find a higher resolution at the URL John gave in his post).
Yes, please do. In fact, use this message as an open permission for evilewan to use any of my posts as he sees fit for the FAQ. Just let me know when you do, so I can give them a once-over and possibly make them a little better!
I retensioned my chain last night before i went to the unicycle club. Its great. It doesnt make loaud noises anymore when each tooth releases the chain as it goes round.
It is not free enought to free wheel (when the wheel is spun), but im really pleased with it.
What is the average time to get about 30% success rate for mounting a 6foot? Ive had it two weeks and im about 30%, if not more.
Pretty close, Phil. We would not have gone through the trouble of removing a wing segment, though… It is called a wing wheel (only used on the ground). The wing-shaped upper portion is larger than the wing so it can slide onto the wing. These contraptures are often built out of old bike parts.
The average is probably related to the type of coaching you have avaiable, as well as live riders to watch doing it. But if you’re already at 30% you’re passed the hard part. For me (and Bradley Bradley who I learned with), the first 1% was the killer. After that, we knew it was only a matter of practice.
We had to figure it out on our own, with no examples we’d ever seen. It took many hours, but we each got it eventually. The most frustrating time was somewhere between the first and second successful mount. After that it just kept getting easier.
Just out of curiousity, how much more difficult is it, particularly for one who is on the short side (let’s say hypotheically about 5’4"), to freemount a 6 foot giraffe as opposed to a 5 foot giraffe? Assuming, of course, the ability to freemount the 5’ giraffe.
You have to take bigger steps (in relation to your size). Otherwise, most of the rest of it is in your mind. Take heart in the fact that your seat is lower than it would be if you were taller. That should help a bit!
