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Ceramic Bearings for Catrike Front Hubs

Bruce on ceramic bearings: I’ve replaced the stock Catrike bearings with ceramics bearings on both of my Speeds. Front and rear. In a year and a half I’ve burned up two of the stock bearings, so I was looking for something that is more durable and that I wouldn’t have to worry about again. It just so happens that they really improve the coasting abilities of a trike, which also means they reduce pedaling effort. But, they ain’t cheap! PRH has just done the ceramic swap in the rear of his trike, and is awaiting the arrival of his new fronts. He felt the improvement from just the rears. If I recall, they are about $50/bearing, and there are four of them in the two front hubs. It takes about ten minutes to replace them in each front hub. Here’s a link to my section on Flickr where I keep my pix of the guts of a front hub, showing the bearings and how they fit. For information on how to remove these bearings, check out this post. It’s easy!

Click here to see pix of a front hub disassymbled.

ABEC stands for Annular Bearing Engineers’ Committee. This committee works to determine the standards for bearings for the Anti-Friction Bearing Manufacturers Association (AFBMA).

The ABEC scale classifies different accuracy and tolerance ranges for bearings. The first column of this table lists the five ratings in the ABEC scale.

ABEC Ratings ISO Class

ABEC1 Class 0
ABEC3 Class 6
ABEC5 Class 5
ABEC7 Class 4
ABEC9 Class 2

The ABEC rating of a bearing is determined by the following (for a 608 size bearing):

1. How close the bore is to 8mm in microns
2. How close the outer diameter is to 22 in microns
3. How close the width is to 7mm in microns
4. The rotating accuracy in microns

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Thanks to PRH for this latest info on these bearings! These are the bearing and part numbers to order them from VXB Bearings. You will note that these are also ABEC-7 bearings, as well as ceramics.

Kit8041 6904-2RS Bearing 20x37x9 Si3N4 Ceramic:Stainless:Sealed:ABEC-7 Quantity 2

same bearing from BOCA Bearings

Kit7660 6805-2RS Bearing 25x37x7 Si3N4 Ceramic:Stainless:Sealed:ABEC-7 Quantity 2

same bearing from BOCA Bearings

Each front wheel uses one 25x37x7 bearing, and one 20x37x9 bearing, so you need two kits, each with 2 bearings, for a total of 4 bearings for the two wheels.

 

For standard Catrike rear hubs you need one of each of these kits from vxb.com:

Kit7653     6000-2RS Bearing 10x26x8 Si3N4 Ceramic:Stainless:Sealed:ABEC-7 (about $30)
Kit8160      6200-2RS Bearing 10x30x9 Si3N4 Ceramic:Stainless:Sealed:Nylon:ABEC-7 (about $33)

I believe that all current Catrikes use the same hubs and bearings. The older front hubs used two of the 6904 bearings, but all of the current models use one each of the above bearings in each hub.

An excellent step up from the stock bearings on a Catrike would be to good stainless steel bearings. The next step would be to stainless ABEC-7 bearings. The next step would be to non-rated ceramics. The top of the line (well, almost!) would be ABEC-7 ceramics. You will note that “Stainless” is listed in the description. That’s because the globes (balls) are the ceramic component, but the races are stainless steel.

The best analogy I can give of the difference in ceramic versus steel balls is the difference between a golf ball and a ping-pong ball, as far as smoothness.

Unless you just have a bunch of money to spend, I would recommend running the stock bearings until one of them gives you trouble, then replace them all with ceramics, keeping the stock ones for spares.

Concerning sealed bearings, they can be lubed. That process is discussed in a separate post located here.

My experience (Bob’s) with ceramics has been that they make a 2-3 mph difference in my riding. I found a roll out hill with a straightaway below it, and I coasted my trike on the test track before and after installing ceramic front bearings. Over about a 300 yard run, the trike went 40 paces (120 feet) further with the ceramics. On all the “go fast” sections of my regular route to work, over the next week I set new personal best times on every section, by about 3 mph. On one section, the new speed ability made me try to complete a 6 block section at speeds above 20 mph. I was successful at that. My usual speed over that route is more like 17, and on some areas I usually drop down to 13 or so.

Bruce says the bearings will get better after 200 miles of run in, so I’ll retest them later.

If you install ceramics looking for speed, you should remove the seals, clean out the grease they come with, add replacement grease, and replace the seals. Excess grease would be displaced by the bearings as they rotate, and would come to rest on the bearing cage. During use, oil from the grease would seep out and lubricate the bearings. But if there is so much grease that the bearings have to continually push it aside you will lose any speed advantage the ceramic bearings might have given you. When you replace the grease, you can also make a batch of “thin” grease to pack the bearings with, made of 70% grease and 30% 3-in-1 oil. The picture below shows how much “thin” grease I added.

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Replacing the Rear Wheel Bearings on a Catrike

John Dunlop, Pneumatic Tires

A ten year old boy in Belfast Ireland rode his tricycle on cobblestone streets, but its solid rubber tires made the ride uncomfortable.  His father, a Scottish veterinarian named John Dunlop thought of an idea for making the ride smoother.  He took lengths of rubber garden hose and fitted it around the rim of the tricycle’s wheels, and glued the ends together to make a tube.  Then he put an air valve in the garden hose, and pumped up the hose with a soccer ball air pump.  The ride was greatly improved, but the tricycle was soon set aside for other toys.  About a year later, it was noticed by a friend of Dunlop, a bicycle racer.  A newspaper article attracted interest, and Dunlop and investors went on to develop an air filled tire for use by the “killer ap” of the day, bicycles, in 1888, soon to be followed by use in automobiles.

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The pnuematic tire, combined with Starley’s basic bicycle design, made a modern one speed bicycle.  The early bike tires were tubular, and glued or wrapped onto the rim, which was dished to accept the tubular tire.  Clincher tires came later.

The pneumatic tire had actually been invented earlier by engineer Robert W. Thompson, in 1845.  However, that was before the huge popularity of bicycles, so the invention went undeveloped.

Replacing (Catrike) Wheel Bearings

Says Bruce:

With the wheel removed from the trike, remove the six screws that hold the brake rotor on and set the brake rotor aside. Now, remove the black, stepped-spacer that slips onto the end of the bearing spacer tube. It is being held on by the o-ring inside, so it may be a little stubborn to slip off, but it will come off with just your fingers.
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You are now looking at the side of the inner bearing, with the end of the bearing spacer sticking through it. With a leather or plastic mallet, gently tap on the protruding end of the bearing spacer tube until the outer bearing at the other end falls out. Push the bearing spacer tube the rest of the way out and turn it around to use to drive the inner bearing out. Just be very careful when tapping on this tube because the shoulders that the bearing inner races ride on is very critical to bearing placement within the hub. Maybe using a wooden dowel of the same diameter would be better to drive the inner bearing out. The inner bearing keeps the bearing spacer centered well enough to use it as a driver for the outer bearing. Now, your bearings are removed. The bearing spacer and the two bearings that go on either end of it, and the stepped spacer, are shown below assembled and disassembled.

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At this point you can relube the old bearings, or install new ones. To relube the bearings, you remove the plastic seals, clean out the old grease with thinner, add new grease, snap the seals in place, and install the bearings. These pictures show those steps. Bruce says that someone who is trying for maximum speed out of a bearing, whether it is a ceramic of a steel bearing, should avoid putting too much grease in the bearing. Real speed seekers can even thin out their bearing grease with 3-in-1 oil, with oil forming 30% of the grease mix, and pack the bearing lightly with this “thin” grease.

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To insert your new bearings, start with the outer bearing, insert it by hand and get it as squared up as possible before driving it all the way in. Slide the new inner bearing onto the protruding end of the bearing spacer and drive it all the way against the shoulder on the spacer. Now, insert that bearing into the hub on the brake rotor side. Using a 1/8″ pin-punch, SLOWLY drive it in, working around the outer race 1/8 circle at a time. Don’t use any kind of press, unless it is a precision press that drives absolutely flat against the bearing. If you get the bearing cocked even a little bit, it wll distort the hub’s recess for the bearing. Not good! Both bearings will be slightly recessed when they are fully seated, with the inner bearing being moreso.

Before starting this process, make very sure that the shoulder inside the hub for each bearing is absolutely clean. Again, this is very critical to the bearing’s location within the hub. Any dislocation of either bearing will cause a preload on both bearings when the wheel is back on the trike. This will create bind and make the trike pull to one side and cause premature bearing failure. Once the bearings are both back in the hub, slip the black, stepped-spacer back onto the bearing spacer tube protrution, making sure that the o-ring inside is in good shape. Now, put the brake rotor back on and you’re done!

When both bearings are inserted correctly, if you spin one bearing, the other should spin with it. The black, stepped-spacer shouldn’t rub on the brake rotor tabs. Once you get the old bearings out, do a thorough cleaning of the inside of the hub, especially inside the machined pockets where the bearings fit.

For more pics of the hub disassembly, refer to trikeblkr’s hub photo archive here.

Replacing Rear Wheel Bearings on a Catrike

SlowWheel Cycling innovation


Nathan Womack is a serious bike rider, serious enough that he wanted to ride at a training pace on rides with his girlfriend.  The trouble was that his preferred pace for training for triathalons was about 20 mph, and his
girlfriend’s pace is more like 15 mph.  He had the bright idea of making a wheel that would give him some resistance in his rides, so that his speed would equal his girlfriends speed, yet give him the training he wanted.

His solution developed into a bike product called the SlowWheel. The SlowWheel is a replacement rear wheel for a bicycle that allows the rider to increase the resistance of the wheel (in order to slow the rider down). Using the SlowWheel, Nathan and his girlfriend are able to ride together, and both get a workout!  The wheel can also be set to no resistance at all, for maximum speed.

Additionally, Nathan looks to have a children’s model out (for children under 5) that will go on a small bike with training wheels to help "slow" the child down as they learn to ride a bike. This will help in coordination as well as be an incredible safety device (as the children will not be able to get going so fast they get out of control).

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