Tools, Charts, and Restoration Tips
Article List
Links & Resources
Gear CalculatorCalculate Ratios, Rollout, Speed, etc
Gear Comparer ToolCompare two gear sets and recieve a detailed listing of differences
(Version 1.0)
Fork Geometry CalculatorCalculate Rake, trail, offset, and other aspects of the front forks
(Beta Version)
Spoke Calc LiteWeb Based Spoke Calculator
(Coming Soon)
SpocalcSpocalc is a Excel based spoke length calculator. Link goes to the page about this calculator
Restoration & Wrenching Articles
Mothers Alum and Mag Polish on HubsJon Fischer7/28/2007 
Methods & Tips on Mounting Tubular TiresJon Fischer8/14/2007 
Modern Component Groups on Vintage FramesJon Fischer7/25/2007 
Bolt Circle Diameter (BCD)

Measurement of BCD is found by measuring from center to center of two adjacent holes:
Multiplying this dimension by 1.7 will give you the actual BCD for a 5 bolt chainring, multiply by 1.4 for 4 bolt chainrings

BCD Reference Table (5-hole rings)
BCD (mm)Smallest RingC-t-C (mm)Application
1514488.8Pre-67 Campagnolo Standard
1444184.6Old Campagnolo Standard, some current track cranks
1353979.5Modern Campagnolo Standard
1303876.4Road Double and Triple Outer 2 rings. Most Shimano Road
1283875.2Nervar Cranks
1223871.7Stronglight 93 and similar
1183669.4Ofmega, SR
1163568.2Old Campagnolo Standard
1103364.7Touring double, Standard triple outer rings
942955.4Compact triple outer
923053.3Shimano Dura-Ace triple inner ring
862850.5Stringlight 99, some SR triples
742443.5Standard triple inner ring, paired with 110, 130, 135mm
562032.9SunTour compact
Vintage Campagnolo BB Spindle Guide
Crankset TypeThreading / BB WidthSpindle LengthCup Type
NR/SR Double 77-87BSC 68mm114.5mmThick Cup
GS Double 77-87BSC 68mm114.5mmThin Cup
NR/SR Double 77-87French 68mm114.5mmThick Cup
GS Double 77-87French 68mm114.5mmThin Cup
NR/SR Double 67-77BSC 68mm112mmThick Cup
Pre-78 GS/RecordBSC 68mm112mmThin Cup
NR Double 67-77French 68mm112mmThick Cup
Pre-78 GS/RecordFrench 68mm112mmThin Cup
NR Triple 77-87BSC 68mm123mmThin Cup
NR Triple 77-87Italian124mmThin Cup
- For Italian double ring BB spindles, add 1 mm to BSC/French lengths. Record ("NR") and SR all use the same arms at any given time in history. An SR crankset only has different chainrings than Record. Otherwise, they are identical. BBs are not!! There are four types: GS, Record, Nuovo Record, and Super Record (Ti spindle, Alu cups).

- Use of pre-78 cranks on post-77 spindles will result in cranks sitting 1.5 millimeters too far outboard.

- From 1958 - 1972 Record crank arms were not dated on their back side
- From 1973 - 1979 the year of crank manufacture is the last digit in a diamond
- From 1980 - 1984 the year of crank manufacture is the last digit in a circle
- "11" in a rectangle means 1985, "22" means 1986, and "33" means 1987
Bicycle Part Standards
Clamp DiameterApplication
22.2 mm or 7/8"Steel bars on BMX or old MTB
23.8 mm or 15/16"British Steel bars: often on old 3sp or drop bars
25.4 mm or 1"Standard ISO size. Many vintage bicycles sold in the US used this size
25.8 mmUnoffical in-between size produced to fit either 25.4 or 26.0
26.0 mmItalian Standard for drop bars.
26.4 mmCinelli Standard up till 1998 when they moved to 26.0
31.8 mm or 1 1/4"Modern oversized Road standard
Bottom Bracket Threading
StandardThreadingAdjustable Cup ThreadFixed Cup ThreadShell WidthNotes
British/ISO1.370" x 24 tpiRightLeft68mmBritish/ISO are interchangable
Italian36mm x 24 tpiRightRight70mmFixed Cup Prone to unscrewing itself
French35mm x 1mm (25.4 tpi)RightRight68mmFixed Cup Prone to unscrewing itself
Swiss35mm x 1mm (25.4 tpi)RightLeft68mmSame as French but Left threaded fixed cup
Rear Drop-out Spacing
WidthCog #Notes
120mm5sp, 6sp UltraStandard spacing for 10-seed road bikes up till early 80's
126mm6sp, 7spStandard spacing for road bikes during the mid 80s through early 90's
128mm6sp, 7sp, 8spTransition Spacing, not an offical standard. Some bikes were built with a spacing of 128mm to accept either 126 or 130mm wheels.
130mm7sp, 8sp, modern 9/10spCurrent modern spacing for rear wheels starting with 8sp. Some 7sp bikes also were speced with a 130mm rear
A steel bicycle frame can be cold set from a smaller spacing to a wider one by one of several different methods. Usually it is only advisable to go from 120 to 126 or 126 to 130mm. Spreading the dropouts too far can cause damage to the frame in the form of breaking bonds at the brake bridge or similar problems.
See the Glossary term Cold Setting for details on how to cold set a bicycle frame.
Note: You Should Never attempt to cold set frames made of aluminum, carbon fiber or 753 steel.
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