Nexus 8 and Alfine 11

[12 Bore]

Hi, just joined as I noticed a thread with reference to Alfine 11.
My question... My wife has a Trigo Up (trike) with a Nexus 8 fitted, she has just started cycling again following a back operation and could do with a lower bottom gear.
I presume I am correct that by fitting a lower number teeth chain ring would do the trick, but this would reduce all 8 gears.
SO
If I was to fit the lower number teeth chain ring and the Alfine 11. This would do the same to all 11 gears.

 

[CXRAndy]

Hi, just joined as I noticed a thread with reference to Alfine 11.
My question... My wife has a Trigo Up (trike) with a Nexus 8 fitted, she has just started cycling again following a back operation and could do with a lower bottom gear.
I presume I am correct that by fitting a lower number teeth chain ring would do the trick, but this would reduce all 8 gears.
SO
If I was to fit the lower number teeth chain ring and the Alfine 11. This would do the same to all 11 gears.

Yes a smaller chainring will reduce all gears. This will improve hill climbing ability

The ratios of the alfine closely match the Nexus 8, the extra 3 gears are at the top end and are only for faster top speed.

Reading the specifications the Trigo UP has a 36t chainring. Fitting a 34/33/32 will help

Also the reading up the standard model Trigo has a triple chainset, could you not add this to her trike?

I see they sell retrofit ebike kits- these seem quite expensive, when something like the Tongscheng TSDZ2 ebike kits are much cheaper and could well fit the trike-little investigations to find out.

 

[GuyBoden]

If you don't have a chain tensioner or half link chain, getting the correct chain length after changing the chainring will be your main problem.

Alternatively, you could change the rear wheel's sprocket, that would be less expensive too.

Standard three speed Sturmey Archer sprockets fit Alfine 8 hubs, they are less expensive than Alfine and have a larger range.
I'm using the 22T on my wife's bike.

https://www.ebay.co.uk/itm/Sturmey-...-15-16-17-18-19-20-21-22-T-/371178337699?var=

 

[12 Bore]

Thanks for your reply. To give you a little more info.
The Trigo has the retrofit ebike kit, therefore has only a single chain ring and has 38 teeth.
My thoughts were to reduce chainring size to gain 1 or 2 lower gears and retain either equal or 1 to 2 above (ie 9 & 10) but I was told by local bike shop through shimano that the nexus 8 and alfine 11 had the same gearing … Bottom gear (1 & 1) and Top gear (8 & 11)

on both were the same., which seems odd to me as I have looked at the ratios for both..
Nexus 8
gear 1 - 0.527
gear 8 - 1.615
Alfine 11
gear 1 - 0.527
gear 11 - 2.153​

To clarify on your reply, a smaller chain rin would reduce gearing to make it easier to climb hills and if the alfine 11 was fitted it would perhaps give her a higher gear for cruising on flat or downhill, otherwise her cadence would be off the map
Any further thought would be great

 

[12 Bore]

If you don't have a chain tensioner or half link chain, getting the correct chain length after changing the chainring will be your main problem.

Alternatively, you could change the rear wheel's sprocket, that would be less expensive too.

Standard three speed Sturmey Archer sprockets fit Alfine 8 hubs, they are less expensive than Alfine and have a larger range.
I'm using the 22T on my wife's bike.

https://www.ebay.co.uk/itm/Sturmey-...-15-16-17-18-19-20-21-22-T-/371178337699?var=[/QUOTE

Chain tension is done by adjusting body length

 

[CXRAndy]

Thanks for your reply. To give you a little more info.
The Trigo has the retrofit ebike kit, therefore has only a single chain ring and has 38 teeth.
My thoughts were to reduce chainring size to gain 1 or 2 lower gears and retain either equal or 1 to 2 above (ie 9 & 10) but I was told by local bike shop through shimano that the nexus 8 and alfine 11 had the same gearing … Bottom gear (1 & 1) and Top gear (8 & 11)

on both were the same., which seems odd to me as I have looked at the ratios for both..
Nexus 8
gear 1 - 0.527
gear 8 - 1.615
Alfine 11
gear 1 - 0.527
gear 11 - 2.153​

To clarify on your reply, a smaller chain rin would reduce gearing to make it easier to climb hills and if the alfine 11 was fitted it would perhaps give her a higher gear for cruising on flat or downhill, otherwise her cadence would be off the map
Any further thought would be great

So already fitted with motor. Is this not sufficient to help her climb? What wattage is the motor quoted and cutoff speed?

You can use bikecalc.com to calculate all sorts of gear combinations to give you a good idea which way to go. Your idea is sound, a smaller chainring and Alfine11 to get back a little top speed

@GuyBoden suggests a different gear on the hub will alter ratios. By trying different combinations and the alfine 11 you could improve by quite a bit

 

[MichaelW2]

You can lower gear ratio by increasing the size of the rear sprocket.
Note that chains come in two width, 3/32 ( normal 8 speed derailleur) and wider 1/8 ( singlespeed)
Hub gears can run either chain width but wide sprockets can only be used with wide chains.

I have run both systems on my Alfine but note that the wide 1/8 sprockets from Sturmey Archer are a fraction too thick for the Alfine hub snap ring to secure. I had to take a bit of the thickness with emery paper. You only need to slim down the centre where the snap ring fixes.
I have reverted to Shimano 3/32 and can't really see any difference in wear rate.

 

[Yellow Saddle]

To clarify on your reply, a smaller chain rin would reduce gearing to make it easier to climb hills and if the alfine 11 was fitted it would perhaps give her a higher gear for cruising on flat or downhill, otherwise her cadence would be off the map
Any further thought would be great

No, that's not true. Both would give exactly the same range. The Alfine would simply have more intermediate steps.

 

[Ajax Bay]

I think the OP has suggested that, in fact, the Alfine has a wider range as well as 3 more intermediate steps, so with a smaller chainring, or a larger sprocket, this would meet the OP's aspiration.

Nexus 8
gear 1 - 0.527
gear 8 - 1.615
Alfine 11
gear 1 - 0.527
gear 11 - 2.153

 

[CXRAndy]

No, that's not true. Both would give exactly the same range. The Alfine would simply have more intermediate steps.

Alfine 11 has a gear range of 408%

Nexus 8 ,.......... 307%

The steps are similar from 1 to 8. then the Alfine 11 continues

 

[CXRAndy]

Some speed calcs using 20" wheels 155mm cranks. a 22t gear on the hub. I punched in three chainring sizes. 38,36,34

Thanks to Sheldon Brown who has the all the figures for IGH. Speed at 80 rpm is displayed for each chainring

First image is Nexus 8 hub



Alfine 11



Looking at the numbers, going to a 34 chainring would give a little bit for climbing and a fair leap top speed if Alfine 11 was fitted.

Going with a 33 or 32t chainring would give further lower gear benefits and still a little at the topend with Alfine 11 fitted see below

 

[Yellow Saddle]

I think the OP has suggested that, in fact, the Alfine has a wider range as well as 3 more intermediate steps, so with a smaller chainring, or a larger sprocket, this would meet the OP's aspiration.

Alfine 11 has a gear range of 408%

Nexus 8 ,.......... 307%

The steps are similar from 1 to 8. then the Alfine 11 continues

Thanks, I now get it.

 

[GuyBoden]

My Wife's bike has a Alfine 8 hub and she struggled pedalling up hills. This year, I changed the rear hub sprocket to a Sturmey Archer 22 teeth and that improved the gearing, so she can now pedal up hill in an easier to pedal gear.

So, you might be able the keep your Nexus 8 hub and just change to a larger rear sprocket or smaller chainring.

As mentioned in another member's post, I calculated the gearing using Sheldon Brown's gearing calc too:
https://www.sheldonbrown.com/gear-calc.html

 

[Pegasus00]

I have a problem with Nexus 8 hub.. Noise and vibration can be heard and feel during pedaling, especially in gear's 4 and 8. The pedals spin along with the wheel when you stop to pedaling.. it's really annoying. I think to buy Alfine 8 or 11 hub for next season. Sorry for bad English, i hope we understand me (:

 

[CXRAndy]

I have a problem with Nexus 8 hub.. Noise and vibration can be heard and feel during pedaling, especially in gear's 4 and 8. The pedals spin along with the wheel when you stop to pedaling.. it's really annoying. I think to buy Alfine 8 or 11 hub for next season. Sorry for bad English, i hope we understand me (:

Have you had the hub serviced? It seems a common misconception that they dont need a service. Most Shimano hubs lack sufficient lubrication. Learn how to strip down and lubricate your Nexus 8.

See this link. https://forum.cyclinguk.org/viewtopic.php?t=93935&start=60