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the gearbox thread

LaharDesign

Monkey
Jun 16, 2006
159
0
Let's limit it to viable, rideable, existing dirt-worthy contraptions with pics.
awroight.
I'm thinking a gearbox thread should have a list of viable and/or pretested transmission principles. many tinkerers on the wave, some may bear fruit. KeepItSeperateStoopid.

Planetry
two shaft toothed cog
three shaft toothed cog
Derailier one or both ends
variable cone friction systems belts or otherwise
splitcycles with cam or crank producing easily converted linear leverage.
pneumatic drives
hydraulic drives
electromagnetic
electromagnetic superconducting
variable diameter chainwheel systems
variations of many of the above incorperating recyclic braking.
bet I've missed some?
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Dodzys had trouble resizing his pic, may be emailing it to me to post, sometime or other...

I could add parallel permanent mesh chains, definately viable.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
honda could have done their CVT far more smooth and efficient with Cams instead of crankshafts. 2 parallel systems not 4, no 6 meshed cogs losing at least 3% and no wobbly gears. no rear drive chains either.
They suffered high energy loss from high speed reciprocation at 20x as many cycles per second as previous examples of this type on bikes. with engage and disengagees of the sprag clutches on the output sprocket over 100 per second its not surprizing that it dissipated loads of energy as noise.
Lots of expired patents here and very simple principles, construction and 99%+ efficiency readily achievable.
 

Gelbwurstbrot

Monkey
Jul 31, 2004
186
10
Franken, Germany
not too far off.
I've added up der parts to around half a pound less than a Rohloff when it replaces the rear hub. In a gearbox config the rohloff leaves around a one pound penalty. I have a 200g one piece tubular carbon crank system with 60g BB that would more than eliminate this weight penalty. I've already more than eliminated it with the low weight of a highly developed Carbon chassis.
You can shave further 60 g from the rohloff with a Rewel titan gripshift
http://www.rewelbikes.com/DE/prodotti/anteprimazoom.asp?IDCategoria=13&offset=0&IDProdotto=34
weights 1/2 costs 2 1/2 :biggrin:
 

ÆX

Turbo Monkey
Sep 8, 2001
4,920
17
NM
Here you go Azza, My name is James Dodds and I have been working on this for the last year . I live just down the Rd from Aaron from Lahar (his bikes are the way forward).
James Dodds - ex Keewee top10 pro (Dh derinbox, onboard diskbr)

i would like to see the inboard disc brake.

the first gearbox bike i made i braked thru the chain to a onboard disc. it didn't work to good for me. what have you done?
 

xy9ine

Turbo Monkey
Mar 22, 2004
2,940
353
vancouver eastside
Hows we all email rohloff service@rohloff.de and say "give us a paddle on each bar!"
I reckon me and Cameron might have some clout.:bonk:
i am so down with that. the grip shift seems to be the largest criticism of the rohloff system, i'm surprised they (or someone else) haven't come up with a solution yet. giving them some feedback is a good idea - maybe they're just oblivious. is the rumored nicolai trigger being built for the rohloff planetary, or for his own box?

thanks but I won't accept any less than a carbon paddle under each bar.:cheers:
me too, please. on the subject of lightening rohloffs, i wonder if its possible to gut the planetary to reduce the gear range to 7. i've heard that the hub is essentially a 7spd with a multiplier gear mechanism to get the second 7 gears - is that mechanism separable? reducing the gear spread would might make paddles an easier feasibility (the twist pulls alot of cable to cover the full 14 gear range). of course there's the rumors of a lighter / fewer geared rohloff that have been floating around for a while...
 

joe99

Chimp
Jul 7, 2006
13
0
I worked on the trigger with Kalle and it was intended for both GCON boxes. I loved the shifter when I finished but i dont know how much it will change up until the point of production
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
Bike builders:
- Lahar www.laharbikes.com
- Honda www.honda.com
- GT www.gtbicycles.com
- B1 www.beone-bikes.com
- Nicolai www.nicolai.net
- BCD www.bcdracing.com
- Orange www.orangebikes.co.uk
- Nox cycles www.noxcycles.com
- Alutech www.alutech-bikes.com
- Solid bikes www.solidbikes.de
- MBK
- MSC www.mscbikes.com
- Racebike www.racebike.cz
- Ellsworth www.ellsworthbikes.com
- Richi-engineering www.richi-engineering.de/images/gallery/71.jpg
- BikeSchrott
- Centurion
- Diamondback www.diamondback.com
- Kelly's bicycles
- Devilwork cycles www.dw-cycles.com
- James Dodds - ex Keewee top10 pro (Dh derinbox, onboard diskbr)
- Rob Metz -Ex Avanti/Keewee designer (all mountain derinbox)
- Krutor www.krutor.cz/bikes/hrotor/cz.htm

Gearbox web resources:
G-BOXX.ORG www.g-boxx.org

Gearbox makers:
- Suntour www.srsuntour-cycling.com
- Universal Transmissions www.g-boxx.com
- Hayes www.hayesdiscbrake.com
- Rohloff www.Rohloff.de

Hub makers:
- Shimano www.shimano.com
- SRAM www.sram.com
- Rohloff
- Sturmey-Archer www.sturmey-archer.com
- Fallbrook Technologies www.fallbrooktech.com
- Nupace www.freeridehubs.com

Rumors:
Rocky Mountain? Specialized?, Santacruz? Evil?

Are we going to include transmissions on rigid bikes?
Evil a rumor? Thats funny!

http://www.evil-bikes.com/structures_2013.htm

I personally did all of the design work for the first GBOXX "standard", Karl Nicolai welded the front triangle on the Evil 2013i frame for Evil and built 2 Nicolai branded bikes of his own also. They were shown at Interbike 2003. I am sure there are pictures and info online in some archives.

Dave
 

dante

Unabomber
Feb 13, 2004
8,807
9
looking for classic NE singletrack
Evil a rumor? Thats funny!

http://www.evil-bikes.com/structures_2013.htm

I personally did all of the design work for the first GBOXX "standard", Karl Nicolai welded the front triangle on the Evil 2013i frame for Evil and built 2 Nicolai branded bikes of his own also. They were shown at Interbike 2003. I am sure there are pictures and info online in some archives.

Dave
sweet, only 6 more years till we see the preproduction GBOXX Evil at Interbike!!! :cheers:
 

EVRAC

Monkey
Jun 21, 2004
757
19
Port Coquitlam, B.C., Canada
Evil a rumor? Thats funny!

http://www.evil-bikes.com/structures_2013.htm

I personally did all of the design work for the first GBOXX "standard", Karl Nicolai welded the front triangle on the Evil 2013i frame for Evil and built 2 Nicolai branded bikes of his own also. They were shown at Interbike 2003. I am sure there are pictures and info online in some archives.

Dave
Sorry Dave, of course we all know of this bike, but we also heard the project had been shelved. If there is no hope of it ever making it to production, why list it.

The rumor I was refering to was the "Superbox".
 

no skid marks

Monkey
Jan 15, 2006
2,511
29
ACT Australia
Centered weight between legs. Makes the bike more controllable and the rear much more controllable.Also better for accelerating and breaking,and bump control/feel.Also all the bennefits of no deraileur to get smashed off etc.
That hardtail Evil is so cool.
 

JohnnyC

Monkey
Feb 10, 2006
399
1
Rotorua, New Zealand
James Dodds - ex Keewee top10 pro (Dh derinbox, onboard diskbr)

i would like to see the inboard disc brake.

the first gearbox bike i made i braked thru the chain to a onboard disc. it didn't work to good for me. what have you done?

I think I saw it outside the N-ZO tent in Rotorua?? Looked pretty sweet, I'd be keen to see how the onboard disc goes in action
 

EVRAC

Monkey
Jun 21, 2004
757
19
Port Coquitlam, B.C., Canada
I'd be a little concerned about running brake torque through the chain. I would wager the loads are a lot higher that what a human can dish out pedaling, just look at the difference in diameter of a rear cog compared to a 203mm rotor. One can decelerate much faster than accelerate if traction is good, further increasing the loads. I forsee lots of broken chains.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
I'd be a little concerned about running brake torque through the chain. I would wager the loads are a lot higher that what a human can dish out pedaling, just look at the difference in diameter of a rear cog compared to a 203mm rotor. One can decelerate much faster than accelerate if traction is good, further increasing the loads. I forsee lots of broken chains.
Could be right. energy transfer is high. Though less and less on the back as deceleration increases due to weight transfer. Chains can take a lot , especially when they are permanent mesh nicely tensioned and lined up, and your rear sprocket is large.

The tension on a chain from a granny gear with all the weight on the rear climbing with a standing hammering style most probably is more.
 

thaflyinfatman

Turbo Monkey
Jul 20, 2002
1,577
0
Victoria
I'd be a little concerned about running brake torque through the chain. I would wager the loads are a lot higher that what a human can dish out pedaling, just look at the difference in diameter of a rear cog compared to a 203mm rotor. One can decelerate much faster than accelerate if traction is good, further increasing the loads. I forsee lots of broken chains.
Possible, but I doubt it. The braking loads from the rear end alone are relatively low, and when you're using the front brake as well, nearly all your weight is on the front wheel so rear end traction is fairly limited. There is more potential for shock loading though.

Hey Aaron, is Dodds' bike using a positive or negative output gearing? Because if it's a negative gearing, he could actually multiply the braking power... and obviously if it's a positive gearing, the reverse is true.
 

Cave Dweller

Monkey
May 6, 2003
993
0
I reckon it would be fine, if you needed to you could always use a BMX chain.

I reckon that would be a sweet idea, bring as much weight into the middle of the bike, reducing unsprung mass and rotational inertia effects. You could probably use a smaller rotor as well depending on the ratio of the cogs.

You could also build a fully dishless wheel without a stupidly wide hub spacing

I wanna see a pic :cheers:
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Possible, but I doubt it. The braking loads from the rear end alone are relatively low, and when you're using the front brake as well, nearly all your weight is on the front wheel so rear end traction is fairly limited. There is more potential for shock loading though.

Hey Aaron, is Dodds' bike using a positive or negative output gearing? Because if it's a negative gearing, he could actually multiply the braking power... and obviously if it's a positive gearing, the reverse is true.
Power is force x distance squared, so more power is produced or should I say dissapated by a geared up disk, even a smaller diameter one.
 

ÆX

Turbo Monkey
Sep 8, 2001
4,920
17
NM
i did break some chains and also b/c my pivot was concentric got a lot of brake induced sag, like 1/3 of my travel.
 

Downhiller

Turbo Monkey
Sep 20, 2004
1,498
0
CROATIA....europe....CROATIA
dont know if someone put this..

and yes so g-boxx is future ?

what about weight of g-boxx bikes ?!

what is BAD feuters of G-bxx ?!
we all know good but what about bad ??
nothing is perfect so bring it on..


thx sicklines



RB (Race Bikes) definitely aren’t afraid to show off their wares. This billet master piece called the Dragster, was seen by a few at Fort William, earlier in the year. Heck it still has it’s number plate and highland mud all over it. The Perspex side panels seem to show a similar style gear box to the Honda system which was revealed after all the secrecy last year. Basically it’s a cassette and derailleur enclosed in a box…the difference from the G-Boxx system is that the pivot is part of the frame and not an integral part of the gear box.





Suntour are another of the major players when it comes to gear box’s. In fact they even had their own frame made to show it off. However it was the fact that Orange had a “Strange”* prototype downhill bike with one of the 5 Suntour V-Boxx’s, in existence, fitted that attracted most attention…will next years DH bikes come with this option…don’t hold you breathe. The Suntour V-Boxx (7 Speed) looks the more petite of the two main offerings to bike manufactures (See the comparison shot below) …that’s a big old difference on the Q Factor but does that make any odds with downhill, especially with the trend now towards big wide flat pedals? Just what the hell is inside it?











Suntour's Own Bike to show the V-Boxx
ha ha marzocchi on suntour bike, why they ddint put their fork ?!, its pure **** haha














Universal Transmission’s (UT), one of the first developers of the gear box system, produce the now infamous G-Boxx system (approaching it’s 3rd generation of development). First introduced to the mainstream public mounted on Nicolai bikes back in 1998, the G-Boxx has seen major evolution over the last few years. Development work has gained pace with the increased demand for gear box driven bikes, so much so that standard mounting patterns and patent have all been applied for hence UT also have been working closely with other gear box manufacturers (Suntour) to help develop and ensure growth for these new innovative products.







Seen here fitted to another Orange Strange Prototype Freeride bike, is the G-Boxx 2 (14 Speed). The difference from the original G-Boxx system is the drive side has switched to the more traditional right side, leaving the brake back on the left side, where standards have already been set by the brake manufacturers. Inside we know it’s using Rohloff’s technology and expertise it has gained in producing it’s own Speedhub.





So why all the fuss…well it’s like this, gear box’s will continue to be developed, as getting away from the traditional gear changing derailleur and coming up with a bomb proof design is no doubt a mission for most downhill/freeride bike manufacturers…the only thing is chain length, it has to be constant or at least fitted some sort of chain tensioner when the pivot isn’t centred on the drive wheel. The V-Boxx and G-Boxx systems both use the drive wheel centre as the pivot centre.…as for the other multi pivot manufacturers, well it could mean that the drawing board will be coming back to them very soon.




G-Boxx 2 14 Speed (above) V-Boxx 7 Speed (Below)

 

SuspectDevice

Turbo Monkey
Aug 23, 2002
4,180
393
Roanoke, VA
Chains are more efficent for lower power, lower torque loads (like climbing or plain old pedaling) but for the type of pedaling that actually occurs in DH (several short 5-8 second sprints and a few 20 second sprints on a bad course) the efficeny of a gear system is about the same, studies that I have read put the efficency even with a chain driven system above 800 watts. Except for pedaling over to the lift I doubt I have ever done less work than that while pedaling my dh bike.
 

SuspectDevice

Turbo Monkey
Aug 23, 2002
4,180
393
Roanoke, VA
Anyone else notice the v-box orange proto isn't heat treated yet? Must have been a pretty last minute additon to their show lineup, probally due to the scarcity of the suntour trannies.
 

thaflyinfatman

Turbo Monkey
Jul 20, 2002
1,577
0
Victoria
Chains are more efficent for lower power, lower torque loads (like climbing or plain old pedaling) but for the type of pedaling that actually occurs in DH (several short 5-8 second sprints and a few 20 second sprints on a bad course) the efficeny of a gear system is about the same, studies that I have read put the efficency even with a chain driven system above 800 watts. Except for pedaling over to the lift I doubt I have ever done less work than that while pedaling my dh bike.
Just so you know, when you're working HARD (peak power output for most people) you can only put out about 800-900W. If you're particularly fit, it might be up to 1100W or so for about 5 seconds. For most common practical situations on a bike, geared systems are not QUITE as efficient as chains.

I've ridden a couple of Rohloff bikes (plus the Lahar which uses one as the gearbox) and they all have a slight but noticeable sensation of drag when you pedal (seems worse in the first 7 gears too for some reason). It's not a big deal though, and for all intents and purposes (especially considering you can have a more efficient single-chainline suspension system with a gearbox) I think the overall efficiency of the bike is going to be extremely similar.
 

SuspectDevice

Turbo Monkey
Aug 23, 2002
4,180
393
Roanoke, VA
Just so you know, when you're working HARD (peak power output for most people) you can only put out about 800-900W. If you're particularly fit, it might be up to 1100W or so for about 5 seconds. For most common practical situations on a bike, geared systems are not QUITE as efficient as chains.

We aren't talking about a "common practical situation" though, we are talking about DH racing, the drivetrain is pretty much superflous on a DH bike to begin with, and when you DO pedal a DH bike, it is solely sprinting. Any fit racing cyclist can sprint for 5-8 seconds at 800 watts indefinetly (as far as the time duration we are talking about 3-8 minutes) as long as they have 10-15 seconds between efforts.

A good road sprinter, bmx racer or track rider (as in almost any a-pro or above bmxer or cat 2 and above road rider) should be able to put out at least 19watts per KG of body weight, which adds up to about 1300 watts for your average weight Dh racer. I know from first hand testing and exentisve experience working with athletes that you are really underestimating what sort of peak power outputs riders create, and the duration over which they can sustain the effort.

I work with at least 3 kids who are under the age of 22 that put out over 22 watts/kg for a 10 seconds. That is what the kids call Pull, and at that sort of power output, and power outputs significantly lower than that, there is functionally no efficency difference, and there likely can be increases in efficency with mesh gears, but the subject has never been thorougly enough explored with actual elite or even fit cyclists. No one with any decent sort of sprint trusts chains... for a reason.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Top sprinting athletes can achieve 1800w+ in 1 km sprints.
the rohloff efficiency drops from 98%(except for gear11 which is 100%) to 96% in the lower 7 speeds because it has a low ratio mode for gears 1-7 with an extra set of cogs in series transmitting the drive. There is noise in gears 1-7 and a gritty sensation at the pedal that is absent in 8-14, the ratios used for racing. 8-14 feel very smooth and efficient and no perceptable change in this between direct drive 11th and the others.
 

SOil

Chimp
Jun 24, 2005
82
0
Are there any efficiency figures for either the G-boxx (similar to rohloff?) or the V-Boxx?
 

Binaural

Chimp
Feb 19, 2006
29
0
Sydney Australia
Are there any efficiency figures for either the G-boxx (similar to rohloff?) or the V-Boxx?
I read a figure of 96% in a Nicholai catalogue for the G-boxx, and this page confirms it as being between 96 and 98%.

Top sprinting athletes can achieve 1800w+ in 1 km sprints.
the rohloff efficiency drops from 98%(except for gear11 which is 100%) to 96% in the lower 7 speeds because it has a low ratio mode for gears 1-7 with an extra set of cogs in series transmitting the drive. There is noise in gears 1-7 and a gritty sensation at the pedal that is absent in 8-14, the ratios used for racing. 8-14 feel very smooth and efficient and no perceptable change in this between direct drive 11th and the others.
Eh? No such thing as an 100% efficient gear. Otherwise those figures sound identical to the G-Boxx, which is to be expected. To be honest I'd like to see both figures independently confirmed - a gearbox efficiency above 95% is something to be a bit suspicious of, even for low-power high-precision applications.
 

thaflyinfatman

Turbo Monkey
Jul 20, 2002
1,577
0
Victoria
I read a figure of 96% in a Nicholai catalogue for the G-boxx, and this page confirms it as being between 96 and 98%.



Eh? No such thing as an 100% efficient gear. Otherwise those figures sound identical to the G-Boxx, which is to be expected. To be honest I'd like to see both figures independently confirmed - a gearbox efficiency above 95% is something to be a bit suspicious of, even for low-power high-precision applications.

I think you'll find that gear 11 is a 1:1 transmission, and that there are no moving parts between the input shaft and the output shell at that point.
 

LaharDesign

Monkey
Jun 16, 2006
159
0
Thanks FLYFM, of course you can assume 2% losses from the two chains provided they are reasonably clean, lubed and not worn out.
Heres some pics of Dodzy's bike, Rob Metz's in the works and some history. pics courtesy of Metzy.:cheers:
 

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xy9ine

Turbo Monkey
Mar 22, 2004
2,940
353
vancouver eastside
the inboard brake is rad. talk about low unsprung weight. i love seeing more independant builders / designers coming out of the woodwork with advanced designs. seems the big companies are playing catchup now. that whip drive looks neat as well. good to see some big brains working out there!