help me isolate some variables here...

early this year, i was riding my coker v2 and a bearing broke. by then i had over 2000 miles on that bearing, so i understood if it finally gave in.
i bought 2 new bearings, and installed them both. but the minute i started riding i noticed a shift from side to side. the more i tightened it, the worse it spun and naturally the more tension i let off aloud for more play. i found what i thought to be the most neutral position. 60mi later, another broken bearing.
i bought some cheap bearings via internet, installed two at a time. those cracked as well. i then noticed there was play between the inner bearing race and the spindle, to which i applied LockTight bearing retainer which did an excellent job of securing the bearing, but did not eliminate the shift.
i found a local bearing disturber and bought some 6203 skf bearings, applied locktight, and then shimmed out the bottom bracket with aluminum can cut outs. none of this elimenated the knocking sound.

notes–> only leftside bearings cracked
cracks were all on the outer races
i tested spinning the wheel with the tire off

i don’t know what to do!!
anybody have anything to throw at me?

Sorry I don’t have any advice for you…but I was wondering what happened when riding at speed and a bearing breaks?

ha, there was a loud “PING” every revolution or so, it later became more and more frequent.

i was initially worried about something locking up and me dieing, but i rode the 15 mi to get home with a wheel that shifted slightly back and forth.

it’s not at all a danger. :smiley:

that sounds very weird, but maybe the frame leg is twisted?
other than that the bearing clamp could be crushing the bearing from the side?

it sounds like something on the frame is messed up.

uhh, are you tightening the individual bearing caps correctly (even gaps where the bolts go through)

only other thing it could be is … do you have to push the frame in/pull it out to get it on the hub? that could easily destroy bearings.

check your pedals?

my best guess would be the frame as well,

ive tested it with the pedals and crank arms off,

the wheel almost drops in to the frame, not much resistance there…

i don’t have a way of accurately measuring the lengths of the legs though, those could be uneven…

If the rim is central between the fork legs, and the wheel is true, then the fork legs are of equal length.

i tried this out a while ago, but didn’t make any adjustment because i had no tangible number to go off of.
i figured that if either of the legs differed by 1mm, then the wheel would be about 5mm off center.

thanks for the reference point!
dremel sparks will fly tonight!

<threadjack>Hey, someone else who lives in Wisconsin who owns a coker! I live in Madison, we should hook up some time.</threadjack>

ah… but you do not own a coker!
we would definitely clash.

Huh? I actually own a Nimbus 36…


Edit: I typed this in capitals but somehow the site converts to l.c.

The consistent damage to bearing suggests maybe the bearing holders are or have become out of round. An impact to the bottom of the bearing holder might cause something like that. If it’s not a snug, circular fit we’ve learned with other unicycles that it can cause undue wear and premature death to the bearing. Not sure how to check it though, if it’s only a tiny bit out of round it may be hard to detect. You could start by looking at the paint on the bottom bearing holders to check for signs of impact?

My “new” Coker has less than 2000 miles on it because I used my older one for road training and the new one for MUni. No bearing issues yet, except for the bearing holders being too tight from the factory. I left it that way for the first few weeks to see if it would loosen up, but finally did some adjusting and the wheel spun more freely.

Sounds very odd, but it seems to come down to one of two things; the frame or the hub. I know that probably sounds obvious, but those are the two things you need to check. (I am, however, making the assumption that the replacement bearings you are buying are the correct sizes and ratings).

The easiest thing to do is to swap your frame around so that the back faces forwards (and rotate the seat 180 degrees). Then ride for 60 miles or so on new bearings and see if the problem stays on the left or moves to the right. If it moves, it’s the frame. If it stays on the left, it’s the hub.

It would, of course, be just as valid to swap your cranks over and turn the wheel around. Just don’t do both at the same time :slight_smile:


thanks john, but i haven’t rode off more than a few curbs, and i do strictly road riding, but i agree that the bearing retainers could have come out of round…

monkey, good idea! i will rotate the wheel and get some mileage on it.
i know for sure the dimensions are right, but how do you know what grade?
do you mean the abec #? like i said, i bought skf bearings, the same bearing number as listed on, for about the same price, but do they make em in different grades? before i bought any bearings it was a headache to find a durability rating!! almost no bearing would tell you anything but wether the seals were rubber or shields!
id love to hear about some bearing information sites you’ve visited!