Torker girafe cog???

Anybody know of a source for the 28 tooth screw-on hub cog on the Torker giraffes?? All of the track cogs I found only go up to 22 teeth.

Torker USA is part of Seattle Bike Supply, a wholesaler based out of Kent, WA. The TX cog is probably made overseas.

The Schwinn Giraffe used a screw-on 26 tooth or a 3-bolt 25 tooth. I’ve got one each of these in my Uniques’ supplies.

The Seattle Bike Supply site has an on-line catelog but you have to be a dealer to see prices (the site doesn’t seem to be working at this moment). You might want to call them or send them an e-mail.

Are you looking for cogs that are more perfectly round and more perfectly centered? An off center cog or off center chainwheel sucks on a giraffe.

Semcycle is another option for giraffe cogs. I don’t recall how many teeth are on their giraffe cog. But even the Semcycle cogs aren’t perfectly machined to the same standards as track cogs. Still, it’d be better than the Torker cog.

If you’re going for a new cog or chainwheel combo then consider getting a 1 or 2 tooth differential. That will give you even tire wear.

Quamen makes a small chainwheel. Available with 22 to 30 teeth. Dan’s Comp has the Quamen chainwheel. I don’t know if it will fit on the Torker’s cranks though. But if it does work, the Quamen chainwheel with a genuine track cog will give you the most perfectly round and centered drivetrain that you’re gonna get. No slack spots in the chain.

The Sem is 30 teeth, if I remember correctly, so that would go really well with 28 teeth.

Re: Torker girafe cog???

I replaced both chainrings on my current giraffe with 44t and 42t BMX chainrings. In fact, I have a chain and set of chainrings on both sides. For the one that goes on the hub, take time to be precise when drilling the holes to bolt it on. You want to make sure the chain ring is centered on the hub so tension on the chain is consistent.

If yours (lower chainring) is only the screw-on type, I’d recommend you drill the chainring and hub (bolting them together) anyway to keep the two connected nice and tight. Have a machine shop do it or get a tap & drill bit set and use a drill press. Drill the chainring first, leaving the holes smaller than what you need. Screw the chainring onto the hub and drill through both the chainring and hub at the same time with the bit that came with your tap set. Well, you may not want to drill ALL the way through the hub. It depends on how far in your bolts need to go. The initial hole in the chainring should be sized to guide the drill bit that came with your tap set. The makes both hub and chainring holes align perfectly. It also helps to drill one hole in the hub first, tap it and put a bolt in before moving onto the next hole. I’ve had chainrings twist around on the hub when drilling them out. Putting the bolts in as you go helps prevent that.

If you use a BMX chainring, it may be possible to put a spacer between the hub and chainring in order to align (center) them. If so, I’d recommend doing this as it will keep the two about as perfectly aligned as you can get. This is only for the purpose of locating and drilling the holes. Spacers can be made by cutting the end off a piece of pipe.

Good luck!

Wow, what a great covey of suggestions!

I’m generally familiar with bmx cranks and sprockets, but what i had in mind for weight savings and rideability was drilling some holes in the solid steel hub sprocket (like a brake disc kinda thing) then re-threading and bolting it to the hub, and replacing the steel 125mm crankset with alloy. Mr. Dingemans can probably make some 125 alloy cranks with a 74/110 BCD right-side spider, which will accept a 28 tooth bike cog, but I haven’t seen any bmx cranks suitable for cutting and drilling down to 125mm. The 28 tooth bmx crank sprockets aren’t hard to find, but the 28 tooth hub sprocket is.

Has anyone actually converted a giraffe to alloy cranks and a narrower chain??

Yup. I’m not sure about finding cranks that short, but I used 135’s. Look for AC MiniLE cranks. I used a left and a right on mine and added two large chainrings. You shouldn’t notice the difference but if your worried about it, add a larger wheel and use a more aggressive gear ratio. I use 44 on top and 42 on the bottom. If I had the money to upgrade, I’d use a 46 on top. I also increased the wheel diameter from 20" to 24". It pretty much handles the same as it did with 2 22t sprockets. I used two chains, one on each side and a set of chainrings on both sides.

I had some trouble with keeping the two sides aligned and keeping the tension smooth when riding. The chain on one side or the other seemed to bind up fairly easy. I managed to work that problem out now but it was only by tinkering around with it for quite some time. I also had problems with the large chainring rubbing against the frame. The frame had to be cut down, re-shaped and welded to make room for the chainring. If you go a similar route, do yourself a favor and put a rashguard over the upper chainring! The larger ones grab your leg a lot easier and a lot more often than a smaller one does.

Question for john_childs and/or todd1814:

Is that 22-tooth Quamen chainwheel likely to work with the AC MiniLE cranks? In other words, are the bolt holes going to line up? Might the crank attachment get in the way of the chain?

Also what do you use for bolts? Does the crank normally come with bolts?

I don’t know much about single-speed BMX but I’ve been looking for crank options and had about given up. I’ve got 2 giraffes with out-of-round chainwheels. On one of them, the slack position is exactly where I idle.

What a luxury it would be to have a chain that’s tight in all positions!

Thanks,
–Mark

PS I use the heavier size chain (I forget the numbers – 1/4 inch vs 3/16 I think).

“I’ve got 2 giraffes with out-of-round chainwheels. On one of them, the slack position is exactly where I idle.”

Maybe try taking the chain off the wheel, rotating the wheel, and putting the chain back on.

As for cranks, I too looked at the AC mini and it it seems to have a 110mm BCD spider. The smallest chainring that fits on that bolt center diameter is 34t.

My question is: how do you mount a chainring on the wheel? I thought you had to screw on a cog to the threaded hub…are we talking about a different style hub??

See my post above. I aligned the chainwheel with the hub, drilled holes through both, tapped the holes and put in bolts. You have to take a good look at the hub your going to use and make sure this will work. Some hubs are too small to drill into. You might also have to put washers between the chainring and hub to act as spacers. For the top chainring, you need to make sure it will clear the frame. A large chainwheel won’t fit or will rub the frame just below the bottom bracket. I had to modify my frame to make this work. I’ve also done this on 3 frames that didn’t need modifying.

Who made your giraffe? It sounds like poor quality manufacturing to me. Are they too old to take back? Maybe you could complain to the manufacturer and get replacement parts (possibly for free). The changes I made to my giraffe were pretty expensive. I think the hub, cranks, chains & chainwheels were around $500. I was looking for a certain level of quality too though…

unisk8r: thanks for the heads-up that those components won’t work together.

todd1814: the giraffes are both Ebay purchases (as are most of my unis). One is a Matthews. I put a nice track cog at the bottom, so the problem is above. This Matthews has been chopped down to 4.5 foot height. I have a 24" wheel on it.

The other is a Miyata “Tall Flamingo” 5-ft. I guess it pre-dates the “skycycle”. I expected better of Miyata.

I have another Matthews (6 ft) that has pretty good tension. It was initially bad, but putting a nice track cog on it did the job.

unisk8r: Thanks for the suggestion of rotating the wheel. That may help with the Miyata, since it has the original cog down below. Now why didn’t I think of that? I’m looking forward to giving it a try on Saturday.

Thanks!

–Mark

If you have a mountain bike hub with disk brake mounts you can bolt the cog right where the disk would go. There’s an article on 63xc.com about just this type of conversion: Disk Hub / Fixed Hub.

If I was to build myself a giraffe from scratch I’d use a good MTB front hub with a disk brake mount. Bolt the cog to the disk brake mount. Use a good BMX bottom bracket and a good BMX chainwheel with under 30 teeth. And use some heavy-duty BMX chain that is some color other than black.

There’s good BMX stuff available that would work great on a giraffe. I don’t know if you’d be able to find stock cranks that are short enough. You’d probably have to get long cranks, cut them down, and tap new holes for the pedals.

Here’s a picture of the MiniLE crank:
http://www.adventurecomponents.com/minile1.htm
It’s available in sizes from 135 mm to 165 mm. It also has a 110 mm spider.

Cranks with a spider like the MiniLE take a chainring. The MiniLE takes a chaining with a 110 mm bolt circle.

A lot of the BMX cranks don’t have a spider. They use a chainwheel (or sprocket). The sprocket bolts directly to the crank with one (fairly big) bolt.

The Quamen chainwheel will not work on the MiniLE cranks.

But there are plenty of BMX cranks that take a chainwheel (a.k.a. sprocket). The difficulty would be in finding short cranks in the 125 mm to 140 mm range. Most likely you’ll have to cut the cranks down and tap new pedal holes.

The flatland BMX riders like the really small chainwheels. The street BMX riders also like the small chainwheels. It gives them more clearance. They use a really small cog on back so they end up keeping the same gear ratio that they would have on a more typical BMX setup. Now we have quality chainwheels available with as low as 22 teeth. Perfect stuff now for a giraffe.

There are small chainwheels besides the Quamen. Quamen is just one that Dan’s Comp has so it was easy to link to and easy to find.

I haven’t looked closely at the cranks that the stock giraffes are using. But just glancing at them it looks like they’re using a chainwheel mount just like the BMX stuff. If they are using the same dimensions it may be possible to put a nice chainwheel like the Quamen on a giraffe and keep the stock giraffe cranks. Worth looking in to. Take the giraffe to a bike shop and see if a BMX chainwheel will fit on it.

Why would you go with 30t or less? Just curious. I used a 42 on both sides of the bottom bracket, mostly for the look. It actually helps to keep your pant leg from getting caught. (I use bashguards too)

I also wouldn’t use such short cranks again and will probably swap mine out when I get a chance. Short cranks on a giraffe are intended for cruising and to improve speed with a 20" wheel. Longer cranks should provide more torque to the wheel and quicker response on the ground. That seems to be an issue on giraffes, where you want to roll up and over something (like a curb) but can’t get the torque down there to do it. It would probably be easier to roll mount that way too.

A big chainwheel and big cog on a giraffe would just look out of place and out of proportion to me. I expect to see a smaller chainwheel and cog on a giraffe.

But a large and decorative chainwheel and cog could add some style to a giraffe. It all depends on the effect you’re going for.

Theoretically a larger chainwheel and cog will wear longer and be smoother.

My Schwinn giraffe has approximately 140 mm cranks. Some giraffes like the Miyata Skycycle have something like 130 mm cranks. I have never ridden a giraffe with anything less than 140 mm cranks so I don’t know how much control is lost by going to shorter cranks.