I have had three or four of these because they were cheap, it turned out that in the long run it was cheaper to save up and buy a decent bottombracket. Everyone of these that I bought broke in under a month, the same two faults occured each time. 1) Mud and grit easily get past the seals and wear out the bearings causing them to cease or rattle. 2) The ends of the tapered arms round off very easily, even during light XC and commuting use I have rounded them off. Steer clear and buy a decent bottombracket, or even better get the new external type, or if your into jumping and DH get some 3piece cranks. ...
Advantages: Cheap, extremely durable, abuse tolerant Disadvantages: Poor crank choice, may not be suitble for extreme use
What's this?
It is a JIS square tapered BB. And in english...
BB - bottombracket. Screwed into the frame and serves as a mounting point for your cranks.
Square taper - Axle shaft of the bottombracket is tapered. The shaft is wider at the base than it is at the tip, so it ensures a very tight fit when the crank is tightened up. It fits square holed cranks only.
JIS - Japanese International Standard. This is a measure of the degree of taper. There is also the ISO standard used by European manufacturers, such as Campagnola. The vast majority of mountain bike cranks are JIS. An ISO crank may or may not fit a JIS square taper BB depending on the tolerances and amount of wear.
Evolution or Devolution?
In the last few years BB's have undergone something of a revolution. Octalink from Shimano, ISIS from ...
tools which are expensive if you don't plan on doing regular maintainance on a bike. Replacing one involves removing the bolts that hold the cranks on with an allen key (which should be part of every rider's toolkit) and removing the cranks with a crank extractor, the first specialised tool which is available from any good bikeshop at around £10. Having removed both cranks, we need to take the old bottombracket out using either a bottombracket tool (£8) or a set of pin spanners (£10) depending on what sort of bottombracket you have installed already. With an outlay of around £20 in tools just to get the old one out, it's obvious why many people have this done at a bike shop when compared to the £20-£25 for the part itself.
Once the old one is out, you'll need to put the new one in. They're available in different sizes, if you don ...
Product Information for "Shimano ES25 Bottom Bracket" »
Product details
Long Name
ES25 Bottom Bracket
Type
Bottom Bracket
Manufacturer
Shimano
Manufacturer's product description
Shimano ES25 Alivio/Sora bottom bracket Specifications: Splined bottom bracket for use with Shimano Octalink chainsets Oversize BB spindle - large 22 mm diameter hollow cold forged chrome-moly pipe billet spindle reduces weight, increases strength and rigidity Octalink splined axle/crank arm interface - results in more rigid crank assembly compared to square tapered spindle Sealed cartridge assembly with oversize ball bearings - maintenance-free high efficiency rubber seals keep out dirt, mud, and water Cartridge design allows easyinstallation without adjustment
