Help please.

[danieldrough]

Hello chums,
I need some help and advice. As this is my first posting, I apologise in advance for the length and if I'm asking questions that have been asked before. I am a keen cyclist with developing joint problems. I tried an electric bike for the first time yesterday and was absolutely amazed. The model was a Comfort, with a 4 speed Nexus hub. The only problem was that it was the large frame model and slightly too big. The same shop had the Lafree with 3 speed Nexus but I was unable to try it as it was new and understandably the shop didn't want it getting soiled or damaged. It was a very good fit. Would I notice much difference between the two? Would it be worth upgrading the hub before purchase and if so what would be the best option ? I need assistance on hills, not because of strength or stamina problems particularly but because standing on the pedals is causing my knee joints to swell. Any thoughts/ideas would be very welcome.

Thanks in advance

Steve

 

[flecc]

No need for an apology Steve, welcome to the forum where your posts will always be welcome.

The 3 speed's bottom gear is 43", rather high compared to the Comfort's 37". I changed my 3 speed to the 5 speed at a cost of around £200 to cope with my hilly area.

One solution would be for you to get the dealer to change the 3 speed's rear sprocket to an 18 tooth instead of the standard 16 tooth one. That would make the low gear 38", almost the same as the Comfort, but the top assisted speed would be about 13.3 mph instead of 15 mph. Since the 3 speed is easy to cycle on the flat without power, that might not matter since you can pedal as fast as you like when conditions are easy.

If you then found that easy, you could change later to a 17 tooth, giving you a 40" bottom gear and assistance to 14 mph. These sprocket changes are quick, easy and simple for the dealer.
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[flecc]

P.S.

Since seen you live in Devon, so you'd probably need to stick with the 18 tooth sprocket with assist to 13.3 mph. You could still fly down those monster long hills at 40 mph though, chasing the milk tankers!
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[danieldrough]

Thanks for your speedy reply Flecc. The bike is new and I can purchase it for £799. Any thoughts? If I was to change the hub not the sprocket would it be worth fitting 7/8 speed Nexus or the Sturmey now that its available?

 

[flecc]

That's a good price Steve, list was £869 and they are rarely discounted. I'd recommend the SRAM 5 speed as it's proven on these bikes. They take a lot of stick since they are transmitting both the rider and motor power. Those eight speed hubs are very new designs and unproven as yet, and the Sturmey 8 first releases had some failures on pedal power alone.

The only thing against the SRAM is the slower gear change, but it's easy to get used to that.

However, bearing in mind your joint problems, if you feel you'd like a bit more than the 250% range of the SRAM to have a very low bottom gear and a high assisted speed, I'd go for the Nexus 8. Bear in mind that a high assisted speed means less range, since the battery is being used more of the time.

There's more information about these bikes on my Twist site, including some on the gearing on the technical page there.
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[danieldrough]

Flecc

Many thanks. The 5 speed Sram with the 18 tooth sprocket would appear to give the best all round performance. It will of course depend on what the shop is prepared to fit.

Steve

 

[flecc]

You're the customer Steve, the SRAM is available from regular stockists Fisher Leisure and Wiggle Cycle, so the dealer won't have any difficulty in obtaining it.

The standard cable that comes with all these hub gears is too short for electric bikes since the battery makes the wheelbase longer. All the dealer has to do is change the existing cable inner though, or shorten and re-route the existing outer to reuse the inner with the SRAM twistgrip.

There's additional information on fitting the SRAM P5 to a Twist here on my site.
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[Flying Kiwi]

The 5 speed Sram with the 18 tooth sprocket would appear to give the best all round performance. It will of course depend on what the shop is prepared to fit.

Steve

With the SRAM P5 hub on my 2006 Twist Comfort, the original 17 tooth rear sprocket gets me up any hill I've come across with ease (and there are some very steep hills around where I live). I suggest you go with this arrangement as the 18 tooth sprocket combined wiith the P5 will make your legs feel like they're powering an egg beater on the flat in top gear.

 

[danieldrough]

Thanks Kiwi. I've looked at Flecc's Sram table again and can see the virtue of the 17 tooth sprocket. I was amazed at the level of assistance the test bike gave so hopefully with it set up like yours, I won't have problems with hills.