|
|||||||||||||||||
|
|||||||||||||||||
|
|||||||||||||||||
| >Standard vs. Compact What is the difference between "Standard" and "Compact" cranks/chainrings? Standard and compact refer to the Bolt Circle Diameter (BCD) of the crankset. This measurement can have a direct effect on the size of the chainrings, and therefore the gearing available. Standard cranksets have a BCD of 110/74 (measured from the center of one chainring bolt to the center of the bolt opposite, or skipping one bolt between). Compact uses a 94/58 BCD. A standard crankset will accept just about the largest ring that you can find, where as the Compact will usually only accept up to a 46-tooth. On the other end of the scale the compact will accept a 20-tooth granny gear (if you can find it), while the limit on the Standard is 24-tooth. Compact is much more common on mountain bikes. Go Back >Crankset Sizing What do I need to know when shopping for a new crankset? There are several considerations when looking to purchase a new crankset. First, will it be compatible with the other parts on your bike? Make sure that the Bottom Bracket spindle length will be compatible with your new crankset. The length of the spindle required is dependant upon the crankset, and bike frame selected. It is imperative that the spindle length is correct for optimum Chainline. There are now a large number of "spline drive bottom brackets" out there. Make sure that you purchase a crankset that is compatible with this type of system if this is what you have. Your local shop can tell you at a glance. Second, if a mountain crankset, would you like the compact, or standard design? Standard and compact refer to the Bolt Circle Diameter (BCD) of the crankset. This measurement can have a direct effect on the size of the chainrings, and therefore the gearing available. Standard cranksets have a BCD of 110/74 (measured from the center of one chainring bolt to the center of the bolt opposite, or skipping one bolt between). Compact uses a 94/58 BCD. A standard crankset will accept just about the largest ring that you can find, where as the Compact will usually only accept up to a 46t. On the other end of the scale the compact will accept a 20t granny (if you can find it), while the limit on the Standard is 24. Third, consider the length of the crank desired. Most cranksets are available in lengths ranging from 165mm to 180mm, though both extremities may be difficult to come by. 175mm is by far the most common size in mountain cycling, while the 172.5mm length is often used for road bicycles. It has been thought that the shorter crank facilitates a better spin, while the longer crank allows better leverage for the "masher." In reality it has been very difficult to prove an advantage by using a particular length, and so, personal preference must be the determining factor. How are cranksets measured? Crank arm length is measured in millimeters from the center of the crank bolt to the center of the pedal spindle (where the pedal attaches to the crank arm). The most common sizes for crank arms are 165mm, 170mm, 172.5mm, 175mm and 180mm. Crank arm length is generally a function of two characteristics: leg length and riding style. As a point of reference we have provided below recommended crank arm lengths based on frame size and inseam length. These measurements may be adjusted based on riding style, but the majority of riders will find that the recommended lengths will provide optimum performance. What size are the cranks you sell? Unless it is stated otherwise, all the cranksets we sell for mountain bikes are 175mm long. Road cranks are available in a variety of lengths (170mm, 172.5mm, and 175mm). Go Back >Bottom Bracket Sizing How are bottom brackets sized? Bottom brackets (BBs) come in differing spindle lengths and cup threading styles. The bottom bracket must match your crankset in order to provide smooth shifting and quiet operation. On a mountain bike, you must check the width of the bottom bracket shell, that is, the frame in which your BB sits. Generally, steel and titanium bikes will be 68 millimeters wide while newer aluminum frames are usually 73 millimeters wide. Some bottom brackets, such as the Shimano XTR M952 model will fit either size, but you must be careful with others. Road BBs come in two styles, either English threading (68mm), which is the majority, or Italian threading (70mm), which is assumed for most Italian-built frames. Spindles come in two styles... the industry standard tapered square hole and the newer oversized splined steel spindles found in shimano's upper end road and mountain grouppos. These spindles are compatible only with cranks designed to fit a spline drive system...choose carefully. Why is bottom bracket spindle length important? The length of the spindle required is dependant upon the crankset, and bike frame selected. It is imperative that the spindle length is correct for optimum Chainline. How do I measure a bottom bracket? 1) Bottom Bracket shell width: The BB shell is the frame tube into which the BB threads. It will measure 68mm, 70mm or 73mm wide. Measuring the shell is easy. Flip the bike upside down and use a metric ruler or calipers to measure across the shell on a line parallel to the BB spindle. Do not measure any of the old BB if it protrudes beyond the shell. This measurement will also determine which threading your frame is likely to have. 68mm & 73mm shells have English threading while 70mm is Italian. 2) Spindle length: To find the length of the spindle, first remove the crank arms. Then measure the length of the spindle in millimeters from end to end. If your cranks are attached with nuts as opposed to bolts, do not measure the extended threaded portions of the spindle. If you are replacing a BB and are using your old crank, you'll want a replacement BB with the same spindle length. If you are installing a new crank, you will want to use the spindle length recommended by the crank manufacturer. What is "Chainline"? Chainline is the route your chain follows as it runs on your front chainrings and rear cassette. A good Chainline means that your system is running smoothly and you do not have a large overlap. You want to keep your Chainline as parallel as possible to the direction you are going. Avoid using the small chainring with the smallest rear cog, as well as the large chainring and large cassette cog. These combinations will cause excess wear and may cause the chain to fall off the chainring. Go Back >Compatibility What bottom bracket will fit my Shimano cranks? Most new Shimano cranks are splined, so you will have to use a Shimano splined bottom bracket. Also, if you have an XTR crank you will need an XTR bottom bracket. The LX M572 and XT M752 cranks both use the ES71 bottom bracket. Go Back >ISIS What does ISIS mean? The ISIS Drive is an open standard for splined bottom bracket interface. It was designed by Race Face, Chris King and Truvativ as an alternative to Shimano's Octalink. As such, the two are not compatible. Any ISIS crank will fit any ISIS bottom bracket, regardless of the manufacturer. They are not compatible with Shimano however. What's the difference between ISIS and square-taper systems? ISIS technology is the new standard for strength, stiffness, and performance. The spline/flute system allows for a tight, creak-free set-up that keeps everything sandwiched in place to eliminate movement and ensure reliable shifting. The square taper system is still strong and reliable, however, with the ISIS system is the platform for numerous excellent products based on the aforementioned facts. Go Back |
|||||||||||||||||
Parts |
Clothing |
Accessories |
Sette Products
Hot Buys | Bargain Basement | Specials | Shop by Brand | Clothing Blowouts Customer Service | New Product Ideas | Sponsorship | Lowest Price Guarantee | Affiliates FAQs | About Us | Contact Us | Employment | Product Help | Join our Mailing List Site Map | Privacy Policy | Site index | The Vegas Helmet Giveaway Winner
Contact us: email | Phone: (800) 774-2376 Copyright © 1994-2008 Price Point Mail Order LTD. All Rights Reserved. Use of this web site constitutes acceptance of the Price Point Mail Order Ltd. Disclaimer, Copyright and Trademark Policy 
|
|||||||||||||||||
Cranksets/Bottom Brackets
