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Best internal gear hub?

Posted: Feb 14 2010 3:55pm
by Drunkskunk
Who makes the best internal geared hub for putting motor power through?

I know Sturmey-Archer, Nexus, and SRAM all make 7 and 8 speed hubs, and I've red reviews on them from a cyclist's standpoint, but whats best when dumping a couple thousand watts through? Would a Nuvinci be better or worse at high torque?

Re: Best internal gear hub?

Posted: Feb 14 2010 6:39pm
by spinningmagnets
liveforphysics wrote:

"...The Nexus 3-spd hubs are proven to hold up with excellent reliability against the guys using them with Etek-powered trikes. They don't look much different inside than any of the other 3-spd hubs that break, but apparently they didn't cheap-out on the metallurgy and tempering, hardening, tooth profile, etc like the cheapo hubs seem to have done..."

Dug out from my files. I don't have info on the 5-8 speed hubs (so don't assume anything good or bad about them), but the Nexus-3 is tough. Someone else said the same thing, can't remember who right now. Whether for pedaling or E-power, a pedi-cab forum would also have real-world info on high-milage much-abused gear-hubs.

Re: Best internal gear hub?

Posted: Feb 14 2010 6:57pm
by John in CR
I'm one of the ones who has passed that Nexus 3 info on, as has Mitch, but I don't remember the source. I tried a few google search for more info recently, due to fears my still idle pair Nexus 3's may suffer the same result others have had here with high power and geared hubs.

While LFP is here, we may have to just go for the gusto and try to break one. They were incredibly cheap old stock sitting on a shelf at a local LBS, so it's time to offer one of mine up and get to the bottom of it to make sure we're not just passing along hearsay.

John

Re: Best internal gear hub?

Posted: Feb 14 2010 8:11pm
by rkosiorek
i have had a little experience with the NuVinci and more with the Nexus.

sturdy as the Nexus hubs are i think that the NuVinci will handle more torque reliably. now it comes down to price. Nexus is well undet $200. and the NuVinci is near double that.

rick

Re: Best internal gear hub?

Posted: Feb 14 2010 8:19pm
by MitchJi
Hi,

The best is the Rohloff.

This Velo Vision Review/Comparison from March 2008 of Nuvinci, Rohloff, Nexus Alfine 8 and SRAM iMotion 9 Geared Hubs has some useful information: :
http://www.velovision.com/mag/issue29/vv29hubgears.pdf
There’s a common link between the bikes we’ve reviewed so far this issue: they all use internal hub gears – and not just any hub gears, but the newest and latest from Shimano, Rohloff and NuVinci. As I’d also fitted the new SRAM 9-speed to my town bike, the stage was set for a four-way shoot-out.
Yedal likes his Nuvinci.

The Rohloff and Nuvinci have the highest torque rating. The SRAM Cargo 5 is rated for Tandem and Pedicab use.

Gary has a friend who builds cruisers with Eteks. Gary posted the following:
I'm sure the Nexus hubs can handle the power. There's a guy with a bike shop down in San Diego (Rusty Spokes, in Pacific Beach...) who custom builds chopper-style motor bikes, using Etek and Mars motors. He uses these same Nexus 3-speed hubs with these beasts, and they have worked flawlessly, even pumping 15 hp through them. Instead of chain, hoever, his bikes are belt driven, using regular toothless v-belts. There's a little bit of "slippage" when starting out, which is like a clutch. Works great, he says, and these things can hit close to 60 in just 2nd gear. Anyway, he's never had a single problem with any of the Nexus hubs.
I sent the owner of Rusty Spokes an email about the Nexus 8. He said he has never had any problems with the Nexus 3 or Nexus 7. He has never used the Nexus 8 but thinks it would be the same. BTW in my email to the owner of RS he seemed offended :) when I mistakenly stated that Gary said his bikes topped out at around 50 mph in 1st.

Gary posted someplace the opinion based on reviews by DH Mtn bikers the Nexus 8 is stronger than the Nexus 3.

Some useful information here:
http://endless-sphere.com/forums/viewto ... 28&t=15216

Pay attention to this and the following discussion:
Image

Re: Best internal gear hub?

Posted: Feb 14 2010 9:28pm
by swbluto
My most significant concern for the "best internal hub" would be durability. It seemed like "torque limit" was a pretty good rating for this, but this seems to be the input torque and doesn't tell me much about the output torque. Can someone tell me how to calculate the maximum output torque from the data given?

If the "lowest gear" ratio offered is .66 for example, does that make the maximum output torque input_torque_limit*.66 or input_torque_limit/.66 or is it the highest gear ratio offered that matters (And is it multiplied or divided into the input_torque_limit)?

Just wondering what kind of acceleration and thrust is possible from these input hubs. It'd be nice if it was well above what I want. :mrgreen:

Re: Best internal gear hub?

Posted: Feb 15 2010 5:27pm
by Miles
The output torque would be the input torque divided by 0.66, minus the losses. So, if the max. input torque was 100Nm, the max. output torque would be 151.5 Nm less about 5% = 144 Nm [for 3:2 ratio: 150 Nm - losses]

Re: Best internal gear hub?

Posted: Feb 15 2010 7:47pm
by swbluto
Miles wrote:The output torque would be the input torque divided by 0.66, minus the losses. So, if the max. input torque was 100Nm, the max. output torque would be 151.5 Nm less about 5% = 144 Nm [for 3:2 ratio: 150 Nm - losses]
So if the max output torque of a Rohloff is 144 N.M., then the thrust on a 20 inch wheel would be 144 N.M./.508meters = 283 newtons. My scooter puts out like 250 newtons at 6 mph and it doesn't wheelie (just somewhat brisk acceleration), so that seems to be kind of weak for the highly-costly "high quality" Rohloff. :| I wonder how the oft-talked about nexus-3 compares?

Re: Best internal gear hub?

Posted: Feb 16 2010 1:14am
by Miles
How did you get to 144 Nm for the max. output torque of the Rohloff???

100Nm / 0.279 (lowest ratio) = 358Nm

Re: Best internal gear hub?

Posted: Feb 16 2010 2:34am
by swbluto
http://www.velovision.com/mag/issue29/vv29hubgears.pdf

I glanced through it and the side column in the chart said "lowest ratio", but I just now noticed it said "crank turns : wheel turns" in 'fine print' below it(well, not really fine print, but it was "out of the way" in a way). That's probably not the rohloff's gear ratio, heh heh.

Ok, dude, I totally need to find out the nexus-3's lowest gear ratio and its torque limit rating. Well, according to MitchJi, it appears the Nexus 8 was "better" than the nexus 3 according to some mtbr reviews so this inquiry may be inappropriate.

Re: Best internal gear hub?

Posted: Feb 16 2010 3:24am
by swbluto
I started reading reviews at http://hubstripping.wordpress.com/inter ... ub-review/. I thought the "cargo / tandem bike" hubs would be more appropriate for high torque applications. Curiously enough, the Rohloff was listed as one of them.

I looked up the SRAM P5 cargo as it was listed as a cargo hub and they specifically mention the torque limit (And they don't mention it for the regular one, lol) and the gear ratios at http://www.sram.com/_media/pdf/sram/dea ... MY05_E.pdf. It was 85 N.M. and it seems the lowest gear ratio was .67, so the output torque limit would be something like 120 N.M. rounding.

So, eh, I guess this wouldn't be suitable for wheelie like acceleration which makes me lose faith in affordable durable internal gear hubs. If only they made them a little bigger?(Assuming that's the problem with the relatively low torque limits?)

Re: Best internal gear hub?

Posted: Feb 16 2010 3:30am
by MitchJi
Hi,
swbluto wrote:That's probably not the rohloff's gear ratio, heh heh.

Ok, dude, I totally need to find out the nexus-3's lowest gear ratio
You can get the ratios for every hub or almost every hub here:
http://www.sheldonbrown.com/gears/internal.html

Re: Best internal gear hub?

Posted: Feb 16 2010 4:25am
by Miles
I think the low gear on the Nexus 3 is 0.64.

I should imagine the Rohloff is conservatively rated. I doubt the Nexus 3 is tougher.... :P

Re: Best internal gear hub?

Posted: Feb 16 2010 9:25am
by John in CR
rkosiorek wrote:i have had a little experience with the NuVinci and more with the Nexus.

sturdy as the Nexus hubs are i think that the NuVinci will handle more torque reliably. now it comes down to price. Nexus is well undet $200. and the NuVinci is near double that.

rick
I guess I got the best internal geared hub for the money, since I paid only $25 or $30 for my Nexus 3's. I just love finding old stock here, because most places don't adjust their inventory prices for devaluation of local currency which runs 10-15%/year.

Re: Best internal gear hub?

Posted: Feb 16 2010 11:04am
by 12p3phPMDC
Miles wrote:I think the low gear on the Nexus 3 is 0.64.

I should imagine the Rohloff is conservatively rated. I doubt the Nexus 3 is tougher.... :P

The NEXUS 3 has the following ratios: (edit Specifically, the SG-3D55, NEXUS INTER-3 DISC BRAKE HUB, "new" model)
(older hubs may be different, I dunno??)

0.73
1.00
1.36

whereas the Sturmey AW3 and SRF3
0.75
1.00
1.33


pretty close to each other....

Re: Best internal gear hub?

Posted: Feb 16 2010 11:51am
by swbluto
Thanks mitchJi for the calculator!

It appears the lowest gear ratio of the nexus 3 is .73.
The lowest gear ratio of the nexus 7 is .632.
The lowest gear ratio of the nexus 8 is .527.

Assuming the "metallurgical durability", or whatever, of each is pretty comparable, it seems the nexus 8 has the highest output torque rating. It looks like it's about .73/.527 = 1.38 or 38% better than the nexus 3 (85/.527 = 161 *.95%efficiency = 153 NM output torque) which would support the suggestion from whatever mountain-biking forum that the nexus 8 was better than the nexus 3. Still not comfortable enough for me to do power wheelies, but it looks like it may be the best for builds that don't need neck-breaking acceleration.

I was hoping since the nexus 3 would've likely devoted "more space" to each gear than the nexus 8, it would actually have significantly better durability but this doesn't seem to be the case.

Re: Best internal gear hub?

Posted: Feb 17 2010 12:44am
by Toorbough ULL-Zeveigh
while Shimano Alfine has been mentioned previously, not sure why it's been left off this thread?
the SG-S700 has more gears, more evenly spaced & lighter than it's 8-speed predecessor with a range second only to Rohloff.
marketed towards MTB's with helical cogs, i should think stronger too; what's not to like?

(all-fine? el-feen-eh???)

Re: Best internal gear hub?

Posted: Feb 17 2010 12:51am
by swbluto
Considering that specs for the 8-speed are findable while the 11 is currently not, I found the alfine's gear ratio specs at http://www.bikeradar.com/gear/category/ ... -hub-31670 .

With a lowest gear ratio of .53 and an input torque limit of, what, 90 NM(?) and 95% efficiency, that would imply a maximum output torque of ~160 NM. That's pretty much the same as the Nexus 8, though it might have better metallurgy.

I was looking for information on the nuvinci and I found a relevant data sheet at http://www.fallbrooktech.com/docs/DevKit_Datasheet.pdf .

It appears the input torque limit is 130 NM while the lowest gear ratio is .5 and it appears popular concensus online seems to think somewhere in the 80% range (let's take 85%), so the maximum output torque would be around .85*130/.5 = 221 NM. That seems to be somewhat better than the nexus, though not particularly close to the rohloff. Maybe that's getting close to power wheelie territory?

Re: Best internal gear hub?

Posted: Feb 17 2010 2:10am
by Toorbough ULL-Zeveigh
11 Speed Alfine IGH Specs: wrote:jumps: 2 x 17% and 8 x 13%
i think it reasonable to assume probably one of the 3 additional gears will be added to the bottom & not all at the top.
also assume the bottom has the bigger jump.
extrapolating from ur list of lowest gear ratios they certainly seem to decrease by roughly 17%.
wouldn't that make the 11-speed Afine lowest ratio .437 with max torque 195Nm?
half price of a rohloff to boot.

Re: Best internal gear hub?

Posted: Feb 17 2010 10:28pm
by rkosiorek
NuVinci has the following comparison chart as part of it's sale brochure. it gives a visual comparison of some of the hubs being discussed here.
640001.jpg
teaser picture
640001.jpg (73.18 KiB) Viewed 15245 times
the "dual input" NuVinci is one that uses a conventional dual chainring up front.

rick

Re: Best internal gear hub?

Posted: Feb 17 2010 10:54pm
by swbluto
Just thought I'd offer some comparisons to hub motors.

A 100V 100A 5302 crystalyte motor would put out a starting torque in the 170-180 NM region, and a 100V 100A 5305 would put out the highest starting torque at 220-230 NM among the 530x crystalytes. Approximately.

Compared to small hub motors, a 407 motor powered with 48V and 20 amps would put out something like 50 NM at startup.

Re: Best internal gear hub?

Posted: Feb 18 2010 12:30am
by Toorbough ULL-Zeveigh
is there anything preventing the other IGH from stacking the deck in there favour the same way with a double chainring or a hammerschmidt/schlumpf?
don't think i've never seen it done by an oem although i'm sure someone must have.

Re: Best internal gear hub?

Posted: Feb 18 2010 11:58am
by Drunkskunk
Toorbough ULL-Zeveigh wrote:is there anything preventing the other IGH from stacking the deck in there favour the same way with a double chainring or a hammerschmidt/schlumpf?
don't think i've never seen it done by an oem although i'm sure someone must have.
I lose some respect for NuVinci for doing that. They could have left it to stand on it's own merits and been fine.
I also notice they compared it to the SRAM and Nexus 8, but not the Sturmey Archer 8 or which has a range around 360% or something like that.

I love the Idea of the Nexus 8, 308% gear range is better than the 177% 3 speed, But I've also been looking at 5 speed hubs. Strumey archer 5 speed has a 256% range. less than Ideal, but close to the 8 speed range. My theory is the gearing may be stronger since fewer gears are packed into the limited space.

Re: Best internal gear hub?

Posted: Feb 18 2010 6:04pm
by MitchJi
Hi,

This is the quote I mentioned earlier (all quotes from this thread):
http://endless-sphere.com/forums/viewto ... 45#p179900
GGoodrum wrote: I think the strongest Nexus hub is either the "red stripe" Nexus-8, or the newer Alfine, which is also an 8-speed hub. From what I've read, these are the ones the DH guys and other "heavy users" have used. The Alfine has a disc brake mount, which I'm guessing is, or should be important to you.…
swbluto wrote: I was hoping since the nexus 3 would've likely devoted "more space" to each gear than the nexus 8, it would actually have significantly better durability but this doesn't seem to be the case.
liveforphysics wrote: The engineer side of me struggles to see how an 8spd hub could could come near the torque holding ability of a 3spd hub, assuming both designs try to make use of available space in the hub for he gearing. But, if you say it's the toughest, I will get it…
GGoodrum wrote:The 8-speed hubs are about twice the diameter, so from what I understand, the parts are beefier, even with 8 speeds.
GGoodrum wrote:Which 3220 wind do you have? With my 7-turn, it has a kV in wye mode of 97. Assuming you are running a 12s LiPo setup, and 12t/100t gearing with a 20" wheel, what I get with the S-A and/or the Nexus-3, is a top speed of 20 in 1st, 27 in 2nd and 37 in 3rd. With a 26" wheel, the numbers go up to 27/38/48, respectively.

I can also tell you that with my setup (20"/3220-7t/11t-94t/12s3p Turnigy LiPo...), it has enough low-end torque in first that it flips me right off the back end, with no problem. :)

-- Gary
Is that a wheelie?

Re: Best internal gear hub?

Posted: Aug 05 2010 12:17am
by johnrobholmes
Im looking to build up a bike with some gears in the rear or on a jackshaft. Leaning towards the Alfine 8 for now, although the weight penalty of installing it is making me cringe. Anybody else planning to use this hub?