Bicycle Mechanics - Question about Madsen Bucket bike BB

I have a friend with a Madsen and her crankset is really wobbling. It looks to me, only having a few minutes to check it out in a dark garage, that either the BB is shot or something is loose. The cranks are tight on the spindle.

Being a massive retro-grouch and C&V guy for the most part my experience on newer bikes (anything made in the last 15 years is "new" to me) is somewhat limited.

I'm assuming this is a cartridge BB. I'm not even sure I have the specialized tools to take apart this particular crank. I've got a Park Tool Shimano/ISIS wrench and a Park Tool CWP-7C Universal Crank Puller (as well as a full compliment of regular hand tools and BB tools to work on loose-ball BB's on C&V bikes (Park Tool HCW-5 Lock Ring Spanner, HCW-11 spanner, SPA-6 adjustable pin spanner -that sort of thing.) These may or may not help me in removing the cranks and inspecting/working on the BB I have no idea what to expect when taking apart the BB on a Madsen -and trying to find any info online on the bucket bike and what kind of BB is uses is pretty fruitless.

I plan on giving it my best shot tomorrow but I am not confident that I have all the tools I need and should add to my arsenal. I don't want to hit a wall and not be able to finish the job and come back later to get the bike working again. That may be the case anyhow should a new cartridge BB need to be ordered. If I can get it apart at least I can measure it and find out what it is by reading the markings on it maybe to order another.

Since the bike is only a year old and doesn't have THAT many miles on it I'm hoping the BB is OK and maybe the cartridge is just loose. Hopefully riding it like that hasn't damaged the BB threads and a simple tightening will make it right.

Anything else I should expect -or any specific tool I'm going to certainly need to source that I don't already have?

bundle of assumptions there .. like lots of owners of that bike frequenting this forum..

some pictures will help.. details of that bike, and a layout of what tools you have.

[comparing part numbers to what the item is , is a lot of bother on this end ..
I didn't feel a need to memorize that ]

Yup, this is the Bicycle Mechanics forum...

Not much has changed.

Yup, this is the Bicycle Mechanics forum...

Not much has changed.

I'm not really sure what that means but without further detail, it's hard to offer decent help. Once you are able to see the bike in the light of day, you could check to see what crank it is and that might shed some light on what BB was used. I could only offer a best guess since I have never worked on one of those. It is too bad thier website didn't offer any help. The photos there show what appears to be a basic single speed crank that I would guess is attached to a simple cartirge BB . Your standard crank puller should work. A trip to the LBS should yeald you a BB tool if you do not have one. Most likely, they used a cheap BB and it has failed early. Any decent LBS will stock a suitable replacement. Another posibility although less likely, is that the locking ring side was not tightened well and has worked loose. Simply tighten it up.

Thanks for the info blamp28. I do hope that the Shimano-type ISIS bottom bracket tool will fit the cartridge that is used in this Madsen but if not I'll be running to the LBS to buy the correct tool. I so rarely do work on cartridge BB's that I just haven't run into any that didn't work with that tool. I've even worked on a wal-mart Schwinn that used that tool to adjust the loose ball BB.

But the thing I really am hoping is that my "universal" crank-pulling tool will work on the crank. The Park CWP-7c says it "will remove both square taper and splined (ISIS Drive, Octalink) crank arms" -I guess it is time to put that to the test.

It amazes me that a cheap BB cartridge in an <$1200 production bike might only last a year. They don't make 'em like they used to I suppose. Maybe it's just come unscrewed a little bit. The wobble is sudden and "clicky" so it does seem like threads and not just worn bearings.

For future reference:

The Madsen utilizes a simple square-taper cartridge BB with Shimano/ISIS drive spline. The issue with this particular bike was that the BB cartridge had come loose in the shell. Pulling the cranks, tightening up the cartridge from the drive side, and checking the far side cup took approximately 6 minutes total.