Nexus 5 IGH experience ?

General Discussion about electric bicycles.
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qwerkus   10 kW

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Nexus 5 IGH experience ?

Post by qwerkus » Nov 26 2020 1:51pm

Hello,

Has anyone tried the new shimano 5 speed internal geared hub with a bbs02 or hd ? Is is as smooth and quiet as an alfine 8 ?

thanks for your time,

qwerkus

markz   100 GW

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Re: Nexus 5 IGH experience ?

Post by markz » Nov 27 2020 1:54am

Always a good read
https://sheldonbrown.com/nexus8.shtml

Nexus is a family of parts, of which the Nexus Inter 8 eight speed hub is one. The Alfine 8-speed hub is a very similar, higher-end model which has a disc-brake fitting.




More info from random web search

Shimano Alfine 8

Shimano’s Alfine 8 hub was developed for mountain bike use and is designed to be ultra reliable even in extreme conditions, and Shimano say it’s their most efficient yet. Gearing is identical to the Nexus 8, though it’s only found on disc braked bikes, and shares most of its internals with the recent Nexus 8, with labyrinth seals for weatherproofing, and similar needle bearings for increased durability and high drive efficiency. The Alfine’s top-normal internal structure gives improved tolerance when shifting while riding under load, making it ideal for E-bikes and offroading, while the double roller clutch engagement also gives a smoother quieter shift.

Shimano Nexus 7

Shimano’s super-reliable Nexus 7 hub offers all the low-maintenance reliability of the traditional 3-speed Sturmey Archer hub that your grandad used, but with a much wider range and smaller steps between the 7 gears, giving gearing equivalent to an 11-27 7-speed cassette. With a typical chainring and sprocket combination of 40/19 the bottom gear is 36 inches and the top is 88 inches, enough for modestly hilly terrain. The shift is smoother and faster than the old hub gears, and you can change gear at a standstill (no more lifting up the back wheel at the traffic lights!) With no shifting between sprockets, the chain lasts ages, and can be enclosed, and the hub itself needs servicing only every two years or 5000km.

qwerkus   10 kW

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Re: Nexus 5 IGH experience ?

Post by qwerkus » Nov 27 2020 9:16am

All of this is known stuff - although part incorrect. For an instance the alfine 8 doesn't shift at all under load. In fact shifting under load is a good way to break your igh. You have to stop pedaling for a short moment to fully engage the dogs from the axle in the matching gear. Also, not all nexus are v/rollerbrakes. The famous nexus inter 3 has a disc version, and newer nexus 8 come with centerlock mounts. And finally, not all nexus are lower end. There has been a nexus inter 8 premium of similar build quality (precision milled hull, needle bearings, improved seals) than an alfine for every generation of nexus 8 - have two here and you couldn't tell the riding difference if if weren't for the rollerbrakes.

I think the only true test of shimano hubs are take-aparts. Internals don't lie. Sadly not teardown of a nexus 5 so far.

EDIT. I checked available exploded views from current generation of shimano 7 and 8sp ighs and here is the result:

Nexus inter 7(for comparison)
Nexus 8 Disc (non premium)
Nexus 8 V/RB premium
Alfine 8

and finally the new Nexus inter 5 Disc

Apart from the nexus 7, they all look very similar to me. All with needle bearings, and some additional seals for the alfine. Now according to those exploded views, the nexus 5 is closer to the nexus 8 premium than the nexus 8 disc. Also, it's hard to spot "ebike specific" improvements claimed by shimano. The nexus 5 axle doesn't look stronger. Perhaps the first 1:1 gear has additional engagement points with the hull ?

john61ct   100 GW

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Re: Nexus 5 IGH experience ?

Post by john61ct » Nov 27 2020 1:48pm

Any maximum torque ratings available for these?

Rohloff is supposed to be 130 N.m

which is just about enough for me

qwerkus   10 kW

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Re: Nexus 5 IGH experience ?

Post by qwerkus » Nov 27 2020 7:13pm

john61ct wrote:
Nov 27 2020 1:48pm
Any maximum torque ratings available for these?

Rohloff is supposed to be 130 N.m

which is just about enough for me
Shimano is very cautious with hw limits and never comnunicates this kind of stuff openly. Oem deals get you some level of insight though, and as a result some numbers leaked. 60n.m2 seems to be the upper limit, which is wuite conservative.

Good luck with a rohloff. You need special dropouts and a lot of money. Plus you have to like shifting. 14sp is total overkill for ebikes. 5-6 widely spaced gears are much more practicable.

john61ct   100 GW

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Re: Nexus 5 IGH experience ?

Post by john61ct » Nov 28 2020 2:00am

Sure if ones come out that handle high enough torque I'd be happy.

Electric shifters exist?

Heavy tandem / cargo, long steep hills, likely will need multiple motors, the mid drive really is just to keep pedal-contributing on the flats an option, also for limp-home mode.

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