Shimano Nexus is a brand of bicycle components which includes products such as epicyclical gear hubs,

crankset The crankset (in the US) or chainset (in the UK), is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain or belt, which in turn drives the rear wheel ...

s, shifters, brake levers, hub brakes,

hub dynamo A hub dynamo is a small electrical generator built into the hub of a bicycle wheel that is usually used to power lights. Often the hub "dynamo" is not actually a dynamo, which creates DC, but a low-power magneto that creates AC. Most modern ...

s, and a CPU for automatically changing gears. The series is primarily aimed at the "comfort" market such as urban commuters and tourers, and as such is not made to withstand the rigours of off-road or mountain biking. The free-wheeling Nexus internal gear hubs are compatible with Shimano's "roller brake", its version of a drum brake, but not with the Shimano disc brakes used with the higher-end Shimano Alfine internal gear hubs.

History

In 1995, Shimano rolled out its Nexus line of seven- and four-speed internal hubs. These had a new rotary actuator that did away with externally protruding gear shifting elements in the rear wheel. Also, the gear units were able to be shifted under moderate pedaling loads. Shimano had manufactured three speed hubs prior to that, and these hubs were at that point re-branded Nexus. In the early 2000s the 8-speed Nexus hub gear was introduced, having two stepped planetary series mounted downstream of each other. The hub was operated with a twist shifter. By November 2006, The Nexus range came in several ranges (Inter 3, Inter 7 and Inter 8) providing 3, 7 and 8 speed models respectively.

Internal gear hubs

Inter 3 - This hub has three speeds with 36% intervals and an overall gear range of 186%. It weighs 1220 grams stripped in its basic version (without built-in brake). Other versions include coaster, roller or disk brake. Starting from around 2011 Shimano offers a model with a rotary shifting mechanism similar to the one originally developed for the Inter 7 instead of the push rod/bell crank mechanism. Auto 3 - The hub is fitted with a 3 speed automatic gear system, which utilizes a front hub dynamo to power a CPU that automatically changes the three speed internally geared hub. A similar system was built for the nexus 4. Inter 4 - Nexus Inter 4 hubs had four speeds, but the same 186% range as the Inter 3. It only geared up, so a relatively large rear

sprocket A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a roller chain, chain, Caterpillar track, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial ...

was necessary to give a reasonable development when combined with a normal front sprocket. It has been discontinued and spare parts have become hard to source. Inter 5 - Apparently in 2012 Shimano has started making Nexus Inter 5 hubs. A forum discussion contains a link to one of two parts lists at Shimano. Range reportedly 0.75 to 1.545 for a total range of 206%. A glance on the Web confirms: Pricing seems to be near Inter 3, availability in the US seems limited. The Shimano Products Line-Up Chart shows ''For Japan market''. Inter 5E - A 5-speed hub targeted at the e-bike market, launched in 2019. Unrelated to the previous Inter 5 model. Available with a conventional twist-grip for mechanical shifting (SG-C7000-5''X'' series), or with an automatic shifter (SG-C7050-5''X'' series)Shimano Inter 5E Service Manual
/ref> integrated with the Shimano STEPS e-bike system released in 2021.Shimano STEPS blog
/ref> Shimano claims improvements in shifting under torque and rotation durability over the C6000-series Nexus 8 hubs. The Inter 5E shares its hub shell with the Nexus 8, distinguishing itself from the earlier Inter 5. Shimano Nexus Inter 7 hub gear

Inter 7 - The Inter 7 comes in two versions with either a steel or

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

shell, weighing 1860 and 1460 grams respectively, the latter more expensive yet relatively reasonably priced. The gear mechanisms are operated with a Revo Twist Shifter or a simple non-ratcheting trigger shifter and are identical in the two versions, offering a range of 244% with non-even interval percentages of 17,14,17,16,17,16. Inter 8 - The Inter 8 has interval percentages between the gears of 22,16,14,18,22,16,14, and a total range of 307%, comparable to a road bike derailleur gear systems, but as the other Nexus products, it is designed and intended for urban commuter use. The hub comes in a variety of versions, weighing between 1550 and 2040 grams stripped. The newest high end models are internally very similar to the Alfine model.Sheldon Brown about the Inter 8
/ref> The Inter 8 is more tolerant of shifting under load than the Inter 7. Batavus Fryslan hub detail

Roller brakes

The Shimano-invented "roller brake" works similarly to a drum brake, but is fitted to the side of the hub with a special adaptor ring. To provide better cooling the roller brake comes with an integrated cooling disc.

References

{{Reflist Hub gears Epicyclical gearing 1995 introductions