saddlesores

ran across these communal/rental bikes in nanning, china.
wondering what the weight difference would be compared
to a standard chainrings/cogs/chain transmission. also
wonder if they've got a 12-speed version.......

fietsbob

dynamic bikes Comfort, Performance, Commuter and Folding Bicycles - Dynamic

On Bike Share - bike share and bicycle fleet solutions.

I Expect the MFG is there in China.

Weight? Did you use one then weigh it?

saddlesores

no chance to use one, just took some shots while passing by.

according to the website you linked, they gots the foldie bikes and hybrids in
8-speed using shimano nexus hubs.

sheldon sez: "The overall range of the Shimano 8-speed hubs is 307%, and the
steps in gears are a bit uneven:"

Ratio 0.527 0.644 0.748 0.851 1.000 1.223 1.419 1.615
Step 22.3% 16.0% 13.9% 17.5% 22.3% 16.0% 13.9%

not sure how to calculate gear ratios without chainrings....would be
an interesting setup to tour on. no more chain cleaning, no more
worn chainrings/cogs.....

according to the shaft drive manufacturer, "if the same bike was
configured with a chain and sprockets instead of our shaft drive, our
shaft drive bike would be less than 1 pound heavier than the chain bike."

from the site, if my calculations are correct, the 8-speed shaft drive
has a low of 28.34 inches, and a high of 87.1 for 26" wheels.

https://www.sussex.com.tw/shaft-drive.html

fietsbob

% + or - of 1:1 [A gear ratio] (x wheel diameter )

car/truck rear differentials have a gear ratio with similar bevel gears ..

vik 

A friend let me try his expensive shaft driven bike. It was awfully draggy. I took it around the block and gave it back. I'd never ride a bike that inefficient even for a coffee.

It was also heavy, but I can't identify what was due the shaft and what was due to other aspects of the bike.

One bad experience doesn't mean all shaft bikes have to to suck. Having said that I remain sceptical.

djb

Seems to me that chain drive is always going to be more efficient, lighter.
If this had real merit, it would be widespread.

That's my take on it anyway.

DropBarFan

Read a couple of reviews of shaft bikes, they appeal to weekend bikers for simplicity, but reportedly some serious riders use 'em too, esp for harsh conditions. I figure that belt-drive is a better approach.

saddlesores

well, what if they went with a titanium shaft in a carbon fiber chainstay?
also, maybe they could lubricate the shaft and gears with liquid helium!

djb

I should have added, "and cost effective"...

saddlesores

according to the website, or maybe some guys on a forum somewhere, the shaft part thingie
will last around 10K miles. unit replacement cost is $89.

djb

Saddlesores, I still go back to post #5 , I haven't ridden one so can't speak from experience.

ShortLegCyclist

They are sealed against road salt, ice and snow, that's the main reason I got one.

GamblerGORD53

I wuz there last January 17 and 18th and took some pics also. Lots were in motion too.
I bet they ride just like a slow Pashley Princess. I had to pass on trying them with a CC.
Other bikes were strangely few and pathetic. The whole city was getting torn down or rebuilding.

I did get lucky at an LBS there to find a memory foam seat cover that saved my @ss the rest of the ride to Dafang. From there I had to ride the bus to Chengdu.

Actually the first thing I saw in Nanning was a 50 mph blur of an e-bike. Crazy.

Tourist in MSN

If I was running a fleet of rentals that stay outdoors and are used by cyclists and non-cyclists alike, I would want them to work with minimal maintenance and have minimal chance for clothing to get snagged. Weight would be unimportant to me, and heavier might actually be beneficial in that it would likely reduce theft and reduce damage from users that abuse them. Looks to me like those goals have been met with this design.

DropBarFan

DC's Capital Bikeshare bikes are similar, heavy 23 kg despite aluminum frame. Unique design would make it harder to steal/sell. Has 3-speed IGH/chain vs shaft-drive though. Program is amazingly popular both with locals & tourists.