markhr

I'm sure a lot of people will agree that G-boxx is the way forward especially with derailleurs being so easy to trash/rip off. That said there's always room for improvement.

So I've always had this dream that a CVT g-boxx that lets you choose a constant cadence and adjusts itself to the terrain is the way forward. Next best would be a user controlled infinitely variable transmission like the nu-vinci VT hub shoe horned into the G-boxx.

Anyway, this isn't the first time I've asked a Nicolai rep about this but this time the man himself answered.

Not good news, at least from my perspective. Here's a snipped copy of the e-mail and reply.

> Date: Tue, 22 Jan 2008 17:31:40 +0100
> From: nicolais at XXXXXX.de
> To: markhr at hotmail dot com
> Subject: Re: CVT g-boxx
>
> we do not have this plan at the moment
>
> best reg
>
> Karl Nicolai
>
> mark XXXXXXXX schrieb:
> > Sir
> >
> > When will I be able to purchase either a CVT g-boxx or an
> > infintely variable transmission, that is, with no limits on the number
> > or ratio of gears? Do you have a development deal with nu-vinci
> > variable transmission hubs or will you be developing your own?
> >
> > I am a current Nucleon TFR owner and think that it's a great bike. A
> > CVT gearbox that allows me to choose and maintain a constant
> > cadence would make it a truly great bike.
> >
> > Thanks
> >
> > MarkHR
> >

Which brings me to this post. Is there anyone else out there that thinks a CVT(or VT) g-boxx is a good thing and, if so, could they please also e-mail info@g-boxx.com requesting it. I'm hoping that, with enough requests, there'll be some development work done by G-boxx.org in this direction.

Thanks folks

MarkHR

edit: G-boxx 1x7 derailleur in a box



edit: g-boxx rohloff hub in a box 1x14 planetary



edit: honda developed derailleur in a box 1x??



edit: suntour v-boxx 1x9 spine gears in a g-boxx standard box

cryptid01

A manually operated CVT with instant response and equivalent weight to a conventional setup would be great. A "self adjusting to the terrain" feature would totally suck.

markhr

Please explain why that would suck?

A CVT (constant velocity transmission) implies that you choose the input speed (cadence) then the CVT box adjusts itself so that your input speed is always approximately the same. That is 80~90rpm when seated and with the option to change down to 60~70rpm when standing/sprinting or any cadence you choose, terrain independent.

There are some cheap and nasty cvt bicycles already that use a flywheel at the rear deralleur to change gear while maintaining a constant cadence. I'm hoping g-boxx.org can come up with something better.

I'm REALLY looking forward to the day I can go for a bike ride where I only have to touch the gear shifter a couple of times in the whole ride even in the most gnarly up/down terrain. Especially if you're doing freeride/DH where your gearing ratio will always match your speed without any user input, i.e., almost like bombing downhill on a singlespeed without ever spinning out or having to stand on too tall a gear.

The Nu-vinci hub is [(edit) IVT (infinitely variable transmission)] and gives a step-less range of gears but you need to manually change, via twist shifter or similar, gearing ratio to match the terrain. It's the next best thing as your gearing is not limited by how many cogs you can cram into the fairly limited space of a g-boxx. That is, the nu-vinci system currently gives a continuous range of gear ratios from 0.5 to 1.75 with no steps and no limitting cogs.

cryptid01

Because the technique of weight transfer (and therefore handling dynamics) through varying pedal inputs is critical to riding technical terrain. There are plenty of times when cadence doesn't matter one bit, but the ability to pop up the front end is paramount. I don't see how a mechanical transmission could, with pedal pressure as its only cue, discern the difference between my desire to shift to a higher gear while pedaling on a smooth, flat surface and my desire to wheelie my front wheel onto an obstacle, ratchet to squeeze my pedals through a crack, and then wheelie again to drop off the back side.

cryptid01

Mmm. I thought it stood for Continuously Variable Transmission. Wikipedia agrees. Regardless, as I stated, it would be critical for the ratio to be determined by the rider. You're too hung up on the cadence thing IMO. I smell a roadie.

mcoine

My car has a very hi-tech, adaptive automatic transmission.. far more advanced than anything you are talking about here.. but when I drive through mountain passes, or on twisty roads I switch to manual shift, because it really doesn't do what I want it to, when I want it to.

KayGee

Exactly. Who would want an off-road vehicle with automatic transmission? I sure wouldn't.

markhr

wikipedia... - you do realise wikipedia is whatever you want it to be, especially true given that anyone can add/change/make stuff up. Why do you think so many schools, universities and colleges refuse to let students either use it or refer to it.

If you'd looked a little further you'd see that Constant Velocit Transmission and continuously variable transmission are similar if not exactly the same thing (a CVT may contain some form of continuously variable transmission). In my time in Mechanical Engineering lectures I only ever heard Constant Velocity Transmission = CVT used by the lecturers/professors.

https://www.google.com/search?hl=en&q...ransmission%22

Like I said earlier the speed of pedalling is determined by the rider via some sort of shifter mechanism (twist, trigger, etc). Lower for quick power to the wheels (manuals, wheelies, etc), higher for climbs, endurance. I consider the ability to actually ride the bike up almost any hill is paramount even if it's a super DH rig. Whether you choose to or not is your problem but you're not limited by having to choose gear ratios that will only work at speed (being too tall otherwise).

I'm a cyclist, buddy.

I have multiple bikes which ALL could benefit from not having derailleurs.

markhr

Given that the user selects the input speed and there's inherent lag between pedal force and transmission change (but no lag in power to the rear wheel) your ability to manual/wheelie will be unnaffected. The cadence will vary while the gearbox reacts to the change in force. If you've selected a low cadence then it will get lower when you apply pressure and as your speed increases adjust itself back into the range you, the rider, selected.

Your reaction was expected hence the nuvinci hub into a g-boxx alternative. That gives you the same control as any geared system without being limited to a small choice of cogs (1x9 or 2x10 or 3x8 and so on). If you feel that an automatic transmission will never be as good as user input then fine but I'm guessing you'll agree that one gear (or cassette) does not fit all situations.

So some sort of variable transmission with a continuous range controlled purely by the rider may be the way forward for you.

markhr

constant velocity transmission is not at all like the crap automatic boxes in cars which have a couple of gear ratios on cogs and work on a one size fits most (none, in reality) system.

A constant velocity transmission with user controlled input (cadence) gives you an almost limitless number of gears (because there are no sprockets/cogs) within the gear ratios you chose. Need to apply power - change the ratio down. Need to cruise - change the ratio back up.

Think of climbing/bombing your steepest hill without having to touch a shifter but never spinning out of gears or feeling that the gear you're in is too tall. You're cadence will vary slightly as the cvt adjusts itself but should stay, roughly, within the range you chose for the situation.

Technical rock garden that needs a low cadence and instant power - no problem.

Insane uphill climb that usually sees you struggling to change gears to keep pedalling - no problem.

Killer north shore stunts that need smooth pedalling on the way in and power on the way out but you haven't got time to/it's not safe to pedal in between - no problem.

markhr

and is your "adaptive automatic" system based on a series of cogs? or is it a true CVT?

I think you'll find it's the former and a "one size fits most" system. Hence your need to switch it off as soon as the terrain isn't straight/flat.

soccerun8728

I always thought that car transmissions were pretty neat. I mean they can shift gears without stalling a car and also the harness the power of at least 200 horsepower. So that is about 152000 watts of power, while a bicycle transmission (read dérailleur) only has to harness about 400 watts of continuous power or about 1800 watts of power in a sprint. The number of watts produced are based on reading about pro riders.

Also, you keep talking about a CVT, in the US if we see CVT we think Continuous Variable Transmission, whose sole purpose is to increase gas mileage. The CVT is suppose to keep the engine within a limited range of RPM's where the engine is most efficient. However, the design does cut down on how much torque is transferred to the rear wheels. Also, name a car company that currently has a CVT in production, a true CVT not some transmission that they labeled a CVT for marketing purposes. If it is out there then the auto company's spent millions of dollars on research and design. Something I don't see the cycling industry doing, I don't think they can support it and also there isn't a driving force behind the technology to switch.

My guess is if they came out with a CVT or something similar that road bikes would still use the dérailleur as it is lighter and easier to maintain. Very few mountain bikers would want to use the new drive train because they won't buy first generation products as they are sometimes full of kinks. You would end up with a product that might work fantastically but in the end gets a bad rep, is too expensive, or too heavy.

The Nu-vinci hub is a really cool hub and everything but is it worth it with the price premium. A lot of people have problems spending 1400 dollars for a Rohloff hub and that is a more tradition design. The plus side to the rohloff is that it doesn't have dérailleurs but offers the same gear ratios. Also, it is designed to go off-road and be abused something other geared hubs have problems with. The problems with the rohloff is that it needs to have its oil changed every 3000 km and it has a proprietary shifter and brake mount.

Also, I like this post because it is discussing new technology, something that I joined bikeforums for and also there hasn't been any post that are off topic or pointless.

markhr

Thanks and me too. I don't know about topics sliding off track, to me it's just part of the whole eclectic mix that keeps me coming back to these forums over others (mtbr - too slow, rbr - who?, british forums - like walking into the VC forum without a haz mat suit, magazine forums - too low population and post count, cyclingforums - spam more?, etc).

I'm not interested in cars. Sorry, I fail to see the relevance of something with so much inefficient power and trying to compare it to a cyclist.

Ok, so we have a disconnect on terminology. For the purposes of this thread CVT is a constant velocity transmission and continuously varibale transmission is [(edit) an infinitely variable transmission as mentioned in the first post].

Still on cars - as I'm sure you're aware, [(edit) IVT] and CVT constant velocity transmissions do very well (in efficiency and power transfer) in low power situations.

Again, I have no interest in cars. I have however seen at least one senior Mechanical Engineering project for a CVT constant velocity transmission design. There are also a number of existing production CVTs and patents out there. So it's simply a case of licensing and prototyping. Something that g-boxx.org is already very familiar with.

People still ride simplex, sturmey archer, fixed gears, single speeds, flip flop hubs, 10 speeds, 9 speeds, 8 speeds, 7 speeds, 5 speeds, rohloff hubs, g-boxx bikes, triples, doubles, etc. It's not going to change the way people are.

Given the comments on these and many other forums about g-boxx bikes I'd hazard a guess that it's not "new" stuff that's putting people off but the price. Yes, g-boxx is still in infancy but they are a premium product not something cobbled together in someone's garden shed. The Diamond Back bike will be significantly cheaper but it's still nowhere near as cheap as a single speed dirt jump bike.

I am certain that, eventually, a CVT box can be made that is competitive with current mid-range derailleur systems (not everyone can afford or wants rohloff/x0/XTR/record/red or, if you're downgrading, dura ace). I completely disagree that a fit and forget box (similar in maintenance to the rohloff hub) will be harder to maintain than derailleurs which are VERY easy to trash.

The nu-vinci is in early stages but it's a realistic alternative to limiting the number of cogs/sprockets you can fit into a space. They've admitted it's currently too big and heavy and are working to change that. I'd hazard a guess that if the housing was removed/changed to fit into a g-boxx there'd be a fairly substantial weight saving immediately.

The Rohloff is hardly traditional, especially when compared to the fairly crap (strumey archer) internally geared hubs that came before. They designed something, pretty much from the ground up, to work as a bomb proof (relatively ) MTB system. I think they achieved their design brief very well.

You say the problems with the hub - I fail to see how minimising maintenance issues is a problem. Especially with a 10-15min oil change (open cap, drain, rinse, close cap, refill) once a year being the first issue you raised.

I do agree on the proprietary twist shifter though - I've asked them to either make other types or take existing proprietary shifter systems and retrofit a double cable friction system into them but no joy there. Now there's a gap in the market for a small machine shop.

soccerun8728

To me a car can be compared to a cyclist. Sure the ICE is an inefficient device and has terrible power loss through out its entire cycle but a transmission is a transmission. What is the overall difference between a car transmission and a dérailleur. Nothing, they both change gears to go faster or slower, make it easier or harder, whatever you want to call it. But can a CVT transfer the amount of torque that a dérailleur drive can transfer. Gastro said that he wants to do a wheelie, can the CVT transfer that torque and make it easier to "pop" a wheelie, or does Gastro have to work harder to do the same stuff. On my mountain bike I can remain seated and pedal enough to flip my bike over doing a wheelie. It actually isn't that hard, I just forget what gear I am in and over I go.

If a CVT can be as easy to maintain as a rohloff hub that would be great. However, your argument that dérailleurs are hard to maintain doesn't make sense. A dérailleur is not hard to maintain, it is relatively easy to get the thing to shift correctly and get rid of the perpetual noise, if one develops. However, the ability to destroy your own equipment is based on how you ride. In 3 years of hard riding, I have yet to destroy my dérailleur. A lot of my riding is doing urban riding, jumping off curbs that kind of stuff, the rest of my riding is doing north shore style trails or XC trails. I think maintaining and destroying are two different stories.

I would say that to maintain a dérailleur is to oil the chain and make sure nothing else is wrong with it. There isn't an oil change and there are dérailleurs that have been going for 10's of thousands of miles without maintenance. Would a CVT transmission be able to handle neglect. For example, a person walks into a bike shop wants the latest and greatest bike to ride to the coffee shop for the next 30 years. He has no idea how to maintain a bike and he doesn't touch the CVT for decades. Is it still going to be as efficient as it was at the start or is it going to show signs of wear, besides the chain.

The nu-vinci hub is a great design and with some refinement could be a great alternative, but is Ellsworth going to allow other people to make a nu-vinci style hub. I mean don't they own the patent to the hub. Would there be royalty's to pay and how much would they be. If not then Ellsworth bicycles is going to be the only bicycle with a nu-vinci hub and already Ellsworth has a premium price. I know they are great bicycles but would it be worth it. Also, the nu-vinci style hub is on a cruiser kind of bike, would it be able to handle the bumps and bruises that MTB would put it through.

I agree that rohloff completed their design brief very well and I would probably not have a problem with a 10-15 minute oil change. One aspect of cycling for some people is to reduce their carbon foot print on the earth. Changing oil every year or every other year is not going to please the environmentalist in us. Maybe if rohloff found an oil that was less susceptible to break down and could last for a longer amount of time, then maybe they could use a synthetic oil, which is suppose to be less susceptible to break down of molecules.

In terms of proprietary design, what happens if your CVT/g-boxx breaks. Is this years model interchangeable with the original g-boxx or does it have different bolt holes and a different casing. Maybe in order to remain at the same level of components you have to but a new frame that fits the new g-boxx. I don't know my research into g-boxx is lacking, I admit that. Also, if you don't like the g-boxx are there other companies that make a similar product and are they interchangeable. That way it could compete with the mid-range dérailleur stock. I can change Shimano and SRAM dérailleurs out without a problem. They have the same mounting point and the same adjustments, same cable routing, the difference is in the cable pull ratio.

There are some distinct possibilities to this CVT idea. I can see the qualities that it offers to the bike community. However; I think the companies need to actually ask the bike community for their input. Like for the roadies, the system needs to be lightweight and for MTB the system needs to be able to take a hit. I think the bike community is not the professionals with an almost unlimited budget but the person with a wallet and a more down to earth kind of guy. Someone who doesn't have a car of spares following him. All of the new drive train ideas are wonderful ideas, they just need some more time to develop and people willing to try them.

dminor 

I'm not going to wade into the nuance discussion above; I'm just going to answer one of Mark's original questions by saying, "yes," I think that gearboxes (for my main emphasis disciplines) are the future (as I've said before on numerous enough occasions to annoy most people here).

I also feel that rider-selectable gearing is the most sure way to achieve what I want to see - - either by cogs or by what I would prefer to call an IVT (infinitely variable transmission) mechanism.

markhr

cool

Doh! IVT, not continuously var..., which is what was in the first post before I got bogged down in semantics.

cryptid01

I hate to belabor this point, especially since I don't really think it's that important, but yes, I realize that. However, in order to have a meaningful discussion, we have to be on the same page when it comes to terminology. For me, wiki is a good place to start. It saves me from making up my own acronyms and others from trying to decipher them.

If you replace "speed of pedalling" with "gear ratio," then I'm all in. You're taking the long way around and it's confusing the issue.


Manuals require no drivetrain input. Once again your apparent lack of technical offroad biking experience shows through, and it damages your credibility, particularly when you espouse the virtues of your imaginary system as being optimal for that type of riding.


Do you also consider full suspension paramount for road bikes? How about 4 wheel drive for F1 cars? There's a reason they're known as DOWNHILL bikes.

Cool, me too! What a crazy world we live in.

P.S. Do you really have a Nucleon TFR?

dminor 

I will add (another rant that I'm sure some are tiring of ) that I would like to see a mounting-boss system that does NOT dictate that the box becomes a stressed-member part of the frame - - that the option exists to 'float' in a cradle much like a motorcycle engine/gearbox (or the Honda G-Cross). And that mounting can be rotated within a reasonable parameter so that the countershaft location can be altered to fit the frame-maker's suspension design.

Maybe that's asking too much; but from what I've seen of the G-Boxx/V-Boxx/whatever-boxx designs, the design of the box itself seems to dictate how the frame/suspension is layed out.

markhr

ok I'll have to agree to disagree with you there. To me there is a huge difference between low power/low speed transmissions and high power/high speed transmissions.

Personally, I've had bigger issues with derailleurs than rohloff hubs. Not to mention the repetitive chain replacement due to wear (20,000km belt drives here we come but that's for another thread). Get that wrong and you end up replacing chain rings, chain, cassette and jockey wheels.

I'd hazard a guess that a largely maintenance free, sealed box would be more attractive to the recreational cyclist but at this stage, with rohloff hubs and g-boxx gearboxes being so expensive, it's clearly the cheaper option that people buy. A neglected rohloff hub or g-boxx is still going to well oiled and sealed. A well oiled derailleur system wouldn't survive neglect for long especially in damp and/or salt environments.

Does ellsworth own the patent or are they merely using the hub in one of their bikes?

ellsworth bikes - https://maps.google.com/maps?hl=en&q=...-8&sa=N&tab=wl

fallbrook tech - https://maps.google.com/maps?f=q&hl=e...wloc=addr&om=0

USPTO search for patents with "Fallbrook" in them - https://patft.uspto.gov/netacgi/nph-P...FIELD2=&d=PTXT

Unfortunately, apart from commuters and an mtb turned into a commuter I can't find any interweb pics of an off road nu-vinci. As the hub is also being used for gearboxes on ATVs I'd have to say that it could handle a knock.

Ummmm......... O. K.

As I understand it from the extensive product development guidlines and spec's on g-boxx.org website the external dimensions and drive sprocket is the same for all products. Only the internals (chains and cogs for g-boxx or spur gears for v-boxx) and, possibly, shifters (trigger for both) vary. So there are currently two interchangeable and different gearboxes.

I agree - there are probaby going to be differences between road and offroad implementations.

It's taken >> 100 years to get this far so I guess time is the one garaunteed thing.

markhr

Ok, total agreement there.

hence my suggestion that an IVT gear box would be better in your and D-Minor's case

So you've never cheated a manual with a single or partial pedal stroke at the start? ....yeah, right

I didn't say it would be as easy or as comfortable as a steep angled XC rig but what's the point of having to push the bike everyhwere? Get on and ride, whatever the terrain.

As for FS road bikes - check out the Paris-Roubaix bikes

Cars - sorry no interest there.

\o/ - yup

I own Nucleon TFR #49 which was built in 2005 - E-bay rocks

markhr

You've got a point but personally I think stressed member is better than having to build a frame to put the box in. However, there's nothing stopping people either building that or just flipping the g-box and installing it so that it's effectively rotated anti-clockwise 90 degrees. That is, cranks in front of the sprocket/pivot rather than below.

I don't know if you've checked out the suggested different suspension options at g-boxx.org. No chain growth and no derailleur means that it's pretty open to interpretation.

ghettocruiser

Changing the oil in a bicycle hub has a smaller carbon footprint than a quarter pounder with fries.

markhr

finally found a floating gearbox, gearbox bike

https://www.pinkbike.com/news/Millyar...bike-2007.html

markhr

MTBR user "patineto" has collected pictures of derailleur in a box systems - useful for illustrating the space limitation and, imho, the argument for CVT/IVT g-boxx gearbox

https://patineto.smugmug.com/Bicycles/371948

Drew12

Big Question...

Is this easily user serviceable 20 miles back on dirt trails when it takes a crap???

My chain & deraileur are....

quick chain break and we got a SS....