Posts tagged #Bottom Bracket

Square Taper Crankset Woes.

The method of affixing crank arms to a bottom bracket spindle using a square taper system has been around for many, many years now and even though we have had lots of designs since it is a method we still see a lot especially on the comforts and hybrids and anything that comes from a box store.

Because we see a lot of these cranks on the cheaper bikes does not mean that it is a bad method, White Industries make a very high end crank set that uses a square taper fit and Phil Woods produce some of the most expensive bottom bracket cartridges ever in square taper format.

If the square taper crank to bottom bracket interface has ever had a problem it has been with installation and maintenance. The basic principle behind the method is that the crank arm gets tighter as it is drawn onto the square spindle because of the tapering. The most comon issue we see is the crank arm bolt coming loose or falling out completely and the bike is still ridden. Even though the crank arm is tightly fixed onto that spindle with the bolt gone the pedaling action will break the bond within a mile of riding. Now here is were it gets interesting. People just assume that a new bolt when they get home and a wrench to tighten it up will solve it. Wrong. When the arm gets loose and you continue to ride it the square hole in the crank arm just mushrooms out. The crank arms are made of soft aluminum and the spindle is steel. Once that crank arm hole becomes deformed it will never stay put, no matter how tight it feels when tightening it back up. The only cure is a new crank arm.
This is a typical example of a crank that became loose and was still ridden.
This is what they are supposed to look like
The above are pretty generic examples of the square taper cranks that you see on multiple bikes nowadays. Below is a picture of a White Industries VBC crankset and bottom bracket. This one was recently installed on a Ti Moots road frame and made a significant upgrade to the bike.
White Industries VBC crank set in anodized black.
The bottom bracket to match.
One slight issue that you have when using the white industries bottom brackets is the choice of spindle lengths or the lack of choices. In the event that a different length is needed then the Phil Woods bottom brackets are a great alternative.




Yearly Maintenance. (The Bottom Bracket)

 This is the time of the year when the workshop is full of bikes waiting for their annual check up. Mixed in with the bikes that we see every year are the bikes that have just been dragged out of the barn for the first time in 5 years and were put up wet in the first place. Those bikes are always interesting to pull apart and really highlight what can happen to bikes that have suffered some neglect.

However it is just not neglected bikes that have problems, any bike that is ridden regularly and hard throughout the year desperately needs that overhaul before the new season starts. Recently we had just such a bike in the workshop. This bike is one that has been overhauled by us before, not yearly I think we did a frame up rebuild on it 3 years ago, however the bike always is cleaned and lubed on the outside by the owner and kept inside.

Below is a picture of what we found inside the bottom bracket shell, once we had used a breaker bar and 2 of us to get the cartridge out!


 Keep in mind that this is an aluminum frame so that is not rust from the frame itself that you are seeing however aluminum does create a powder like substance under the right conditions. This is a mixture of sweat and moisture that finds its way down the seat tube and also the cartridge itself being steel bodied can supply some rust to the mix as well.

Moral of this story is. "If it looks good and clean on the outside, it doesn't necessarily mean everything is cool inside..."
 
This is a bottom bracket tap. The threads were so damaged after removal we had to re-cut them. Not an ideal scenario but the only option at this point.
This is the material that was removed in the re-tapping.       
Posted on April 2, 2014 .

New Crankset From Sugino


The Road OX801D
          Sugino, the Japanese company famed for making some of the best crank sets to grace bikes through the decades have come up with yet another innovative design that is both stylish and addresses a common problem when choosing a gear combination. Lack of choice.
The MTB ZX801D
           The new OX801D for road and the ZX801D for MTB features a 110 and a smaller 74mm bolt circle diameter that enables the use of rings only usually obtainable on a triple. This new design and the selection of rings available gives you 13 possible combinations. Perfect for those looking for the ultimate touring setup or a cross racer looking for a tweak to the standard configurations. Mtb  options for running a wide gap for a low climbing gear on a tough or muddy course. The choice is yours.
Close-up Showing the 74mm. BCD for mounting  the smaller rings
           The build quality is superb, typical Sugino, and the outboard bearing bottom bracket configuration is very stiff. The setup also gives you the lowest Q factor available when using the lower 74mm mount rings at 145mm for the road and 156mm for the mtb. Let us know what your gear requirements are and we can put together the best combination for you.
Posted on December 6, 2012 .

Bottom Bracket Conversion

          A common problem that arises nowadays, with the influx of new bottom bracket standards is what, why and how to move from one system to another. With the threaded bottom brackets of old there was not many issues with a change to the newer outboard bearing systems but, with the move to frame specific systems, the switch is no longer as simple or, in some cases even possible.
          One of the most common issues is the press fit systems more specifically the PF30 and BB30 standard. Whilst both these systems are good and make for a solid crank interface often the issue arises because the frame has been purchased as an upgrade for a specific build kit already owned and the owner needs to convert the bottom bracket over to a threaded external system. There have always been a couple of options for this however, the good folk at Praxis Works, makers of our favorite chain-rings, have come up with a superb new conversion kit for the purpose.
         One of the biggest problems with conversions and even the press fit systems as a whole is that they tend to creak and groan. This is because the adaptors are, like the bearings, seperate from each other. With the Praxis system the cups are actually conected to each other by means of a threaded sleeve. This sleeve is very tightly machined but also as it is installed it flares out and takes care of any wiggle that may cause problems.
          If you are thinking of doing a conversion or have already performed a conversion with another product take a look at the Praxis system. It is the only way I will go in future. If you want more information or need a kit just let us know as we are Praxis dealers and use the full range of their products.

www.praxiscycles.com

Posted on November 14, 2012 .