What size chainring bolt do I need?

Single bolts are generally between 3.5 – 5.0mm Long. Double bolts are generally between 5.0 – 6.5mm long. Triple bolts are generally 7.0mm or longer. Triple bolts are normally only used to hold the two outer chainrings as the inner will be smaller and screwed directly to the crank.

Are all chainring bolts the same?

Each chainring bolt – the number will vary depending on the chainset design, but is usually four or five – consists of two parts, a female-threaded ‘outer’ part and a matching male ‘inner’. The outer nut has a standard external diameter of 10mm so theoretically the bolts can be used to fit any chainset.

What size are Shimano chainring bolts?

Outer diameter of male bolt across threads is 7.7mm, outer diameter of female sleeve/nut is 9.6mm. Diameter of both across the pan head is 11.6mm. These are the measurements for a Shimano 5700 compact crank 50/34 stock chainrings, for future reference.

Are chainring bolts universal?

The Chainring Bolts Fit for universal single chainring/chainwheel used.

What thread is a chainring bolt?

Bicycle Industry Threads

Nominal Thread Size Example of Bicycle Uses
8mm x 1.25mm Stem hardware, stud type crank nuts, suspension hardware
8mm x 0.75mm Chainring bolt
9mm x 1mm Front hubs, quick-release, Asian manufacturer
9mm x 26 tpi Front hubs, Campagnolo®
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How do you fit chainring bolts?

Securing the nut with chainring nut wrench or hex key, thread the bolt into the nut in a clockwise direction, screwing in just until the bolt feels resistance and the rings are held in place. Repeat for all bolts and then gradually move from bolt to bolt, tightening each bolt a quarter of a turn each time until tight.

When should I replace chainring bolts?

Replace the Chainring Bolts:

– If there is any damage on the threads or on the wrench locations. – If excessive torque was required to loosen the bolts. – If any corrosion or rust or other malady is visible. – If the nut and bolt feel gritty when you are tightening them together.

Do Shimano chainrings come with bolts?

The thing is that the bolts needed for the BB were a larger diameter than the ones with crank, so those are the ones I used. But every time I have bought a Shimano BB, they come with bolts, and every high end Shimano crankset also tends to come with bolts.

Do you need to grease chainring bolts?

In other words all metal to metal threads should be greased or thread-locked…. this seems to be the rule. Yes, grease the chainring bolts. You could try a very very weak thread lock, but grease is enough.

Do all chainrings fit all cranks?

Largely speaking, yes. As long as your attempting to replace them with a chainring(s) designed to work with your chainset. Your cranks will have a specific bolt layout or fitment spec so you can’t just fit a BMX chainring to your triathlon bike.

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How do you measure chainring BCD?

Luckily, it’s possible to calculate the BCD of a chainring by simply measuring the center-to-center distance of two adjacent bolt holes.

Chainrings: Understanding BCD

  1. For 3-bolt chainrings: “A” = “B” x 1.155.
  2. For 4-bolt chainrings: “A” = “B” x 1.414.
  3. For 5-bolt chainrings: “A” = “B” x 1.701.

What are crank bolts?

Crank bolts, as the name suggests, are used to secure the crank to the axle (spindle) of the bottom bracket(BB). While they are another of those parts that may go largely unnoticed by most riders – sometimes they are even covered by a dust cap – they may become loose and worn over time and require replacement.

How do bottom brackets work?

The bottom bracket on a bicycle connects the crankset (chainset) to the bicycle and allows the crankset to rotate freely. It contains a spindle to which the crankset attaches, and the bearings that allow the spindle and crankset to rotate. The chainrings and pedals attach to the cranks.