Bottom Bracket Standards
There are now a wide variety of bottom bracket shells available in the bicycle industry, making "industry standards" a thing of the past. The following article will help clarify which bottom bracket shells we manufacture so that you can choose the right one for your bottom bracket assembly.
A Brief History
The bottom bracket originated around 100 years ago in Europe during a time when taxes and the high cost of transport limited European trade. Italian frame builders sold most of their goods in Italy, the French concentrated on French customers, and the British made bikes for their home market. From the beginning the result was a hodgepodge of design specifications, which continues today.
Overview of a Bottom Bracket Assembly
The bottom bracket assembly on a bicycle connects the crankset to the bicycle and allows the crankset to rotate freely. It contains a spindle that the crankset attaches to and the bearings that allow the spindle and cranks to rotate. The chain rings and pedals attach to the cranks. The bottom bracket assembly fits inside the bottom bracket shell which connects to the seat tube, down tube, and chain stays.
Bottom Bracket Shells
Threaded Bottom Bracket Shells
Threaded bottom brackets have the advantage of being compatible with the largest range of cranks. Traditionally they have two bearing cups that screw into the frame, a right hand (fixed) cup, and a left side cup (adjustable). There are three common types of threading for bottom bracket shells: English, Italian and French. All of our threaded bottom bracket shells are English style, meaning they are 1.370" in diameter, have 24 threads per inch with a thread length of 0.50”, and are right and left threaded (also known as British Standard, ISO/English or BSA); making them compatible with most modern threaded bottom bracket spindles. Our threaded BBs are available in titanium, steel, and stainless steel in varying widths, and are 0.5 mm oversize to allow for finishing after welding.
Threadless Bottom Bracket Shells
BB30: Cannondale released its BB30 system as an open standard in 2006. BB30 bearing cartridges press directly into a precision-fit shell, and stop at removable snap rings that mate with two snap ring grooves in the shell. The key benefits to this system are that it is lighter than a threaded assembly because of the elimination of separate bearing cups, and stiffer due to its 30 mm diameter aluminum spindle. Additional benefits include more room in the bottom bracket area to attach larger down tubes, seat tubes, and chain stays; and because the shell and spindle increase in diameter and not width, the cranks can be made to provide more heel clearance. Our BB30 compatible shells are available in titanium, steel, stainless steel, and aluminum in 68 (road) and 73 (mountain) mm widths. The bearing bore is supplied undersized, 1.640"/1.643" (~41.7 mm), and must be finished to size by the frame builder after welding; the bearings have a corresponding OD of 42 mm.
PressFit 30: The downside of the BB30 system is that it requires more stringent dimensional tolerances to work well, resulting in higher manufacturing costs. SRAM addressed these issues with the introduction of the PressFit 30 (PF30) bottom bracket standard in 2009. Both the PF30 and BB30 use the same 30 mm ID bearings and 30 mm spindle cranksets; the difference is that PF30 bearings are contained inside cups and the cups are pressed into the frame. The shell has a smooth bore due to the lack of snap ring grooves; the outer lip of the cup contacting the frame is what stops the press action. According to Chris Hilton, drive train product manager for SRAM:
"PressFit 30 fundamentally provides all the most significant advantages of BB30 but requires much less precise machining of the bottom bracket shell area, as the bearings come inserted into plastic cups that are easier to fit into the frame and less delicate than a stand-alone bearing. PF30 bottom brackets also have an integrated sealing system, which helps prolong bearing life."
The large ID of the PF30 bottom bracket shell gives it the further advantage of being adaptable to a wide variety of bottom brackets assemblies, including eccentrics. We make our PF30 shells in titanium, steel, stainless steel, and aluminum in a variety of lengths and widths; the ID is supplied .5 mm undersized, to 45.5 mm (1.791"), and must be finished to diameter and width after welding by the frame builder.
41 mm Press Fit/Shimano Press Fit (BB86/BB92): These bottom bracket assemblies are identical to the PF30 except that the OD of the bearing is 41 mm instead of 42 mm. We have recently begun manufacturing these in titanium and steel in will offer them in 88, 91, and 106 mm lengths which allows for facing after welding.
BBRight: Up until 2010, bottom brackets incorporated bearings that were symmetrically positioned around the frame's centerline. Cervélo changed that in 2010 with the introduction of the asymmetric BBright bottom bracket system. BBright and PF30 share the same 30 mm diameter aluminum spindle, cartridge bearings, drive side bearing location, and bottom bracket cups. However, the non-driveside bearing for the BBRight is pushed outward by 11mm. This allows the designer to widen the frame tubes that connect to the bottom bracket shell, making it stronger and stiffer. Our titanium BB0030 measures 2” OD x 80 mm wide, providing 1 mm for facing, and isa compatible with the BBRight system.
Why all the alternatives?
The demand for alternatives to threaded bottom bracket shells grew out of a desire to provide a greater variety of frame sytles that are lighter, stiffer, and cost less to manufacture. With today’s emphasis on cutting edge technology and innovation, new standards are the norm rather than the exception. Our decision to manufacture a given standard will be based on its anticipated applications and longevity in the market.
Download the Paragon Machine Works Products and Price List
12 mm Combination Head Rear Skewers
Our new combination head rear skewers are 100% Paragon-made from black anodized 6061 aluminum and are compatible with all our 12 mm DT Swiss inserts and dropouts. The benefit of these skewers is that they have a lower profile, are lighter, and cost less than the standard and modified DT Swiss skewers. They are threaded M12 x 1 on one end, and the other end has a combination head with an external 15 mm and internal 6 mm hexagon. They are available in 142 (SK4010), 148 (SK4012), 157 (SK4014), 177 (SK4016), and 197 mm (SK4018) lengths. They can be purchased on their own or at a discounted price with a compatible dropout or insert.
Inserts for Flat/Flanged Sliding Dropouts
We now have left side inserts for all of our flat/flanged sliding dropouts that are compatible with a post mount 140 mm rotor disc brake application. DR4049 and B4049 (black anodized) fit a 10 mm skewer, and DR4050 and B4050 (black anodized) fit a 12 mm skewer. All are made from 6061 aluminum.
1" Wide Steel Syntace Dropouts
Our 1018 steel Syntace frame components that are compatible with the Syntace X-12 System are now available in a 1" width, DR2091. The right side frame component accommodates a concentric or eccentric threaded insert, allowing the wheel to be centered in the frame following any inconsistencies in frame construction. The complete assembly for the Syntace X-12 System requires a right side hanger with screw, skewer, and threaded insert that are available for purchase separately here. Syntace compatible skewers are available at a reduced price with the purchase of the frame components.
148 mm Long Skewers
Some of our skewers are now available in 148 mm lengths: DT Swiss RWS 12 mm rear skewer (DT000), DT Swiss Syntace X-12 RWS rear skewer (DT011), and Shimano E-Thru 12 mm rear skewer (SH004). The 142 mm shaft of these skewers has been replaced with a 148 mm black anodized 6061 aluminum shaft manufactured by Paragon Machine Works. The quick release mechanism is the manufacturer’s original one.
Bottom Bracket Shell for 41 mm Press Fit/Shimano BB86/92
Our newest 4130 steel bottom bracket shell, BB2039, is designed specifically for 41 mm press-fit type bottom brackets. The outside diameter is 1-3/4" and it is 91 mm wide, providing 1.5 mm for facing after welding. The inside diameter is supplied .5 mm undersized to 40.5 mm (1.595"), and must be finished to size after fabrication by the frame builder. It is relieved in the center for weight reduction to 42 mm (1.653"). We will also be making a 106 mm wide version of this bottom bracket shell.
Our Summer socks have arrived! Featuring our signature logo and bone lettering, they are made in the USA by Save our Soles from moisture wicking Coolmax, and available in purple, PR93, and black, PR98. All revenues from these sales will go to bicycle advocacy groups through our Giving Back Campaign.
In a continuing effort to improve our website and make it more user-friendly, we have added a quick-add feature to our products. You now have the option to add a product to your cart quickly and easily by clicking on an "Add to Cart" button, rather than having to go to the individual product page. A pop-up screen comes up after you have added the product to verify that it was put into your cart. Exceptions to this are products that have pull down menu options for compatible items, such as skewers and bolts. You are not able to quick add these items to your cart, instead you can select the "Choose Options" button and it will bring you to the product page. Another addition is a quick-link to your cart that can be found under the search bar, allowing you to easily access your cart on any product page.
A big thank you to the customer who asked for the "Add to Cart" feature, we hope that it saves our customers valuable time. If you have any ideas for improving our website please send them to donna(@)paragonmachineworks.com.
Meet Your Maker News
Thanks to the organizational efforts of Sean Walling of Soulcraft Bikes, there are a bunch of Meet Your Maker Tours scheduled over the next six months. The Meet Your Maker Tour is your invitation to ride alongside and hang out with some of Northern California's best bicycle frame builders and component makers.
(L to R: Alec White, Robert Ives, Rick Hunter, Todd Ingermanson, Sean Walling, Mark Norstad)
A big thank you to Caletti Cycles who hosted the last Meet Your Maker Tour on May 30th. We are in awe of their beautiful new work/live space and appreciated them letting us explore it. There was an impressive turn out of builders and component makers that included Soulcraft Bikes, Calfee Design, Black Cat Bicycles, Blue Collar Bikes, Hunter Cycles, Rock Lobster Cycles, and White Industries (our apologies if we left anyone out). Some builders weren't able to make it but were represented by people riding their bikes. One group did a road ride that explored the coastline and mountains around Santa Cruz, and the other went on a dirt ride through redwoods and on swooping single track through Wilder Ranch and above UC Santa Cruz.
Blue Collar Bikes hosted a rockin' MYM ride on June 6th. It started at Bike Dog Brewing in West Sacramento and took us through the beautiful Sacramento Delta, with river and vineyard views along the way. Two custom frames, one made by Blue Collar and the other by Ventana Mountain Bikes, were raffled off and $8500 was raised to benefit Chako Pit Bull Rescue. We are proud to have donated some of the components for the bikes and were sad that we weren't one of the lucky winners.
July MYM Tour
The next ride will be hosted by Retrotec, Soulcraft Bikes, and WTB on July 18th. It will be a mountain bike ride that takes you up Mt.Tamalpais and through the Marin Headlands. Starting in downtown Mill Valley, it will go up Railroad Grade then down Coastal Trail to the Pelican Inn for beers and food. Then it’s up Dias Ridge Trail and either back to town or you can take the long route through the headlands. The shorter loop is about 20 miles and the longer loop is about 30.
For more information and the complete schedule of upcoming rides visit the Meet Your Maker website.
We said a fond farewell to Jerry who retired after working for Paragon for 12 years. We’ll miss his enthusiasm and willingness to jump whole heartedly into any project that came his way. We wish him the best and hope he goes on many exciting adventures during his retirement.
A number of customers have had problems with Paypal token errors when trying to use Paypal on our website. We think we have resolved this issue but appreciate you contacting us immediately with the error code/message if you have any problems. Thank you for your patience
Paragon Machine Works donates 100% of all revenues from the sale of our bottle openers and promotional items to non-profit organizations that promote bicycle safety, awareness, and community. In April we raised $970 for The Friends of Stafford Lake Bike Park.
Live, Ride, Thrive
"The best bike racers, he knew, usually had deep inner demons that they were running away from. Bike racing was like chemotherapy of the soul, burning and cauterizing the bad thoughts."
~ From Wheelmen, Gotham Books, 2013, referring to Eddie Borysewicz, trainer to three-time Tour de France winner Greg Lemond.
We are excited to donate all our revenue to VetBikes.org during the months of May and June, an organization that donates bicycles to veterans to help facilitate their path to wellness. Cycling helps veterans manage their post-traumatic stress disorder and depression, increase their general fitness, and get outside and active in their local community. VetBikes.org uses donated parts to build high quality, custom bicycles that last. Veterans keep them for their own, allowing them to continue cycling therapy during and after graduation from veteran rehabilitation programs. Their goal is that no veteran is denied a rehabilitation opportunity due to a lack of resources, and bicycles are their contribution to this effort. Individuals identified by veteran’s programs as the most likely to become "lifer" cyclists are given first priority for bicycles.
If you don’t need another t-shirt but want to make a difference, consider donating your high quality spare parts and/or bicycles instead. Money donations are also accepted. For more information and photos visit their Facebook page.
We appreciate your support!
Total amount donated to date: $7793
• Sonoma County Bicycle Coalition • National Interscholastic Cycling Association • Friends of China Camp • SF Urban Riders (McLaren Bike Park) • Bike East Bay • Friends of Tamarancho • In Memory of Tom Polermo • Marin Museum of Bicycling • The Friends of Stafford Lake Bike Park
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