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Old 08-04-17, 12:15 PM   #1
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New NYC Citibikes with CVT

Went to grab a bike to run an errand at lunch and saw some spankin' new Citibikes at the docking station. Got one and quickly realized it has continuously variable gearing in place of the 3-speed used in prior models. That was my first time on such a thing and it was kind of cool, and yet somehow disconcerting at the same time to not have a clear "gear". I don't think I got to the lowest ratio because it spun way too fast when I slid down the range. As with other Citibikes, the high gear could have been higher - probably not any different then the series 2 models have.

I also got a distinct impression of the new bike feeling lighter and having more responsive handling. That's not saying much, as most Citibikes have the handling characteristics of a La-Z-Boy.
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Old 08-04-17, 01:22 PM   #2
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I'd like to know who makes the hub. I imagine that whoever engineers those bikes is doing so with an eye towards reliability.
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Old 08-04-17, 03:43 PM   #3
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They are NuVinci hubs, and I recently discovered that they seem to be standard on the newest Citi Bikes, with blue baskets.
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Old 08-04-17, 04:34 PM   #4
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I had no idea a CVT existed on a bike...or was even possible.
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Old 08-04-17, 04:47 PM   #5
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Here's a video of how NuVinci Bicycle CVT works

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Old 08-04-17, 07:18 PM   #6
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I just purchased a Priority Continuum after 20 years of riding a Specialized Hardrock for recreation.

The NuVinci hub is a marvel. I test drove a Cannondale Quick Disc 3, a Kona Dr. Dew, a Fairdale Archer Weekender, and a Breezer Beltway while deciding whether to keep my Priority Continuum during the 30 day trial period.
All of those bikes had great selling points (and the Dew nearly won me over), but what kept me in the Continuum was the smooth and seamless, no-brainer shifting of the NuVinci hub.

The Breezer Beltway is a VERY similar bike to the Continuum, but it's $700 more and the Alfine hub is just not as nice as the NuVinci.
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Old 08-04-17, 07:28 PM   #7
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I think that's very cool. CVT's have been used on cars for decades. I'd be curious to see how it rides. There ought t be an option for selecting your optimum cadence, if not already. Automatic for the people.
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Old 08-04-17, 07:58 PM   #8
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I think that's very cool. CVT's have been used on cars for decades. I'd be curious to see how it rides. There ought t be an option for selecting your optimum cadence, if not already. Automatic for the people.
They have that, apparently. It's called the Harmony system:

Harmony? / Harmony? H|Sync? | Fallbrook Technologies Inc.
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Old 08-04-17, 09:39 PM   #9
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I already constantly fidget , hunting for the right gear on my bikes, even the old one with down-tube shifters. With infinite gears, I may never stop adjusting. And I'm afraid the Harmony cadence system would be just one more lever for me to fidget with. Of course, I'm kidding...I am very curious to try a CVT. Can I get one with drops or bull-bars since that's what works best with my hands. If so, would be a twist grip shifter like on those box-store drop-bar bikes (like the "GMC" Denali)?
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Old 08-05-17, 06:29 AM   #10
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I am very curious to try a CVT. Can I get one with drops or bull-bars since that's what works best with my hands. If so, would be a twist grip shifter like on those box-store drop-bar bikes (like the "GMC" Denali)?
The only shifting option I'm aware of is the grip shifter, and I don't imagine it would play well with drop bars. There are two wires coming out of it too, because you need to pull in both directions.
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Old 08-05-17, 07:25 AM   #11
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The only shifting option I'm aware of is the grip shifter, and I don't imagine it would play well with drop bars. There are two wires coming out of it too, because you need to pull in both directions.
My hands don't do well with straight bars anymore, but on my 20-year old MTB-based commuter I installed inboard bar-ends which help approximate riding on the drops (plus an aero bar). My main commuter and old road bike have traditional drop bars. If I found a CVT irresistible, and they had only straight bars, that's what I would do. But I'm sure some bike or parts manufacturer will come out with a CVT-equipped drop-bar road bike at some point. I imagine the purists will complain, especially if it has e-assist, disc brakes and wide tires.
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Old 08-05-17, 07:36 AM   #12
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I imagine the purists will complain, especially if it has e-assist, disc brakes and wide tires.
I've loving wide tires. I've modded my CVT bike to run some of those new, road plus tires from WTB. The Byways. 47mm wide. They are wonderful on gravel and double-track, and on potholes.

Were I implementing a CVT shifter on drop bars, I think I'd consider some sort of left- and right-hand trigger system in which the left and right triggers opposed each other, pulled opposite cables to the hub, and maybe squeeze left to increase resistance, and right to decrease it. Something like that. Maybe.
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Old 08-07-17, 11:47 AM   #13
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Here's a video of how NuVinci Bicycle CVT works

https://www.youtube.com/watch?v=kVPjhmTThPo
That's pretty cool. I rode another one and got a bit more familiar with the idea of 'trimming' the ratio on the move.
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Old 08-07-17, 12:18 PM   #14
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and I don't imagine it would play well with drop bars.
I see quite a few twist-type shifters on drop bars and quite a few brifters running IGHs.
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Old 08-07-17, 01:48 PM   #15
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That's pretty cool. I rode another one and got a bit more familiar with the idea of 'trimming' the ratio on the move.
And can you trim while stopped?
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Old 08-08-17, 02:28 AM   #16
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I think that's very cool. CVT's have been used on cars for decades. I'd be curious to see how it rides. There ought t be an option for selecting your optimum cadence, if not already. Automatic for the people.
Ironically modern car CVT's use electronics to emulate a normal gearbox, because it feels better to customers. That way there's no advantage of having the engine rev at the most efficient speed while the CVT has quite a bit of mechanical drag. The NuVinci also has more mechanical drag than a regular IGH, but I guess the power/mechanical drag ratio of bikes is much better, but I don't think the difference between the efficiency of human cadences is a great as the revs of a car engine.
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Old 08-08-17, 03:18 AM   #17
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I would imagine the NuVinci hubs do wear. But, perhaps they are more forgiving to poor shifting and more predictable with failures than other hubs.

I think the basic IGH hubs have a problem that if one doesn't get a clean shift while coasting, then it will wear the gear selector, and eventually begin to skip. Perhaps also a little finicky with shifter adjustment.

Do they do an inspection all all the bikes periodically? A skipping IGH might only be picked up with a test ride which would be expensive.

Anyway, I would imagine CVT hubs are being used due to an expected better/cheaper fleet servicing that would offset the higher parts cost.
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Old 08-08-17, 03:27 AM   #18
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I would imagine the NuVinci hubs do wear. But, perhaps they are more forgiving to poor shifting and more predictable with failures than other hubs.

I think the basic IGH hubs have a problem that if one doesn't get a clean shift while coasting, then it will wear the gear selector, and eventually begin to skip. Perhaps also a little finicky with shifter adjustment.

Do they do an inspection all all the bikes periodically? A skipping IGH might only be picked up with a test ride which would be expensive.

Anyway, I would imagine CVT hubs are being used due to an expected better/cheaper fleet servicing that would offset the higher parts cost.
I ridden about 45252176483475 city bikes (honestly, probably 100 or so; 12 different in the last year) around Europe when travelling and living around. Everyone I visit has a spare 3-/7-/8-speed IGH parked outside in the constant rain/snow (they never see inside at all.)

I've never had one skip, ever!. On occassion, they fail to shift, but this seems to happen after about 10-20 years of usage and after the thick rubberised coating is worn through due to accident/falling over which allows water to touch the cable.

Buy, I've never had one skip.
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Old 08-08-17, 07:11 AM   #19
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And can you trim while stopped?
Hm, I don't exactly recall. Which makes me think the answer is yes, since I tend to gear down after stopping at lights and I didn't notice that it wasn't changing to a low gear.
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Old 08-08-17, 07:53 AM   #20
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Hm, I don't exactly recall. Which makes me think the answer is yes, since I tend to gear down after stopping at lights and I didn't notice that it wasn't changing to a low gear.
Yes, you can gear down while stopped. Sometimes I don't get the full range of turn when the bike is stopped, and I might have to pedal a half turn to free up whatever in the hub is stuck. That behavior's not consistent though, and right now as I try on bike that is right next to me I get the full range of motion.
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Old 08-08-17, 03:31 PM   #21
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Yes, I've ridden a few Citi Bike bikes with the NuVinci hub. Each time I ride one, I like it more. I got one yesterday and had a lot of fun with it. The bottom ratio is insanely low, but given that we want little people to be able to ride it, I won't complain. It's hard to make a bike that pleases everyone, and they struck a good middle ground.

I believe these bikes have the N330 model which means the top ratio is 3.3 times the bottom one. There are N360 and N380 models available. There's probably not much point in using them on the bike share bikes.

I've adjusted the ratio while stopped and while pedaling. It just works. Whee!

And yes, the bikes get frequent maintenance. I've read about it. The repair depot is extremely busy. When docking a bike, you can press a button next to the wrench icon which will lock the bike, turn on a red light, and take the bike out of commission until a mechanic picks it up. Then you can give feedback in reply to an email they send you automatically.
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Old 08-08-17, 07:45 PM   #22
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Hm, I don't exactly recall. Which makes me think the answer is yes, since I tend to gear down after stopping at lights and I didn't notice that it wasn't changing to a low gear.
Cool, thanks. I often forget to change gear before stopping. That would be handy
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Old 08-10-17, 09:09 AM   #23
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I've had an N360 on my opafiets for 7 or 8 years now and don't want to go back to a static gear IGH. It does take a bit of getting use to but once you do it's quite wonderful. I can usually shift while stopped but occasionally will find it locked in place. I've wanted to ask Nuvinci why but never remember.

According to friends @ Citibike the primary reason for these is reliability and providing a better experience for riders. They'd found that bikes would often go 20 - 30 rides stuck in a single gear with nobody reporting it so are hoping that the more reliable Nuvinci's will eliminate that, reduce maintenance, and keep more bikes operable. As @noglider says "It just works. Whee!"
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Old 08-10-17, 11:36 AM   #24
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How can they tell a bike has been ridden without working if it's not reported? And is the NuVinci really more reliable than a 3-speed? If so, I'm even more impressed.

Andy you will get used to it. It didn't take me long. One of my big complaints about IGHs is the wide spacing. This completely eliminates that.
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Old 08-10-17, 01:27 PM   #25
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How can they tell a bike has been ridden without working if it's not reported? And is the NuVinci really more reliable than a 3-speed? If so, I'm even more impressed.
Is it possible the advantage is that less shifting discipline is needed? The Nuvinci tolerates shifting while pedaling, and I've shifted mine under some pretty heavy loads while standing and pedaling. Is it possible that Citibikes incur damage from being shifted under load when they shouldn't be? Maybe that's not it. I'm just genuinely curious.
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