Nexus 8 Questions...
 

So I rode out to the LBS today and low and behold met the coolest guy in town. I thought the coolest guy in town was me :D . Well, this guy works at the shop only on Saturdays and rides a Surly Pacer. Beautiful bike btw. We were discussing a few things and he started talking about the Nexus 8 internal hub. He said I should consider it. Well we were talking about axle space and so forth. He stated that the hub should be able to fit my Ibex Corrida CT. I am not sure if it will or not. Does anyone here know if it would are would not. You can check out the Geometry at http://www.ibexbikes.com . Also, what is the general opinion of this hub? I like the fact that nothing is really exposed but how do you keep it maintained? Is the gearing ratio good for commuter riding in town and around small hills? I would like something durable, dependable, geared right, and easy to maintain. Let me know your opinions for putting this on my bike.

You can put your present gearing sizes into Sheldon Brown's gear calculator. Check for gear inches. Then, after that put in for the Nexus 8 hub (Sheldon's already has the Nexus 8 selection for you, so it's easy) to note the difference. As far as the operation of the hub I think it would definitely be an upgrade. :)

I added a Nexus 8 to an old road frame and really like it. I get eight very usable gears and while the weight is a bit more than my other derailer equipped bike, it is a great commuter. See this link for a couple of pics. Please feel free to ask me any questions.

http://www.bikeforums.net/showthread.php?t=273172

I went ahead and put the numbers in myself. ;)

Your Ibex Corrida ST has the following specs:

Truvative ISO-Flow Triple with chainrings: 48 38 28
Cassette Sram PG-850 with sprockets 11 - 32
Tire size 700 x 28 - 622

170 mm cranklenght (Best guess)

Same setup with the Nexus 8 hub with a 18 tooth sprocket

If you use an 18 tooth sprocket the gearing is almost identical as you have now. You could use a 19 tooth to make the gearing a little lighter.

Here are the gear inches for both:

So georgiaboy, does that mean the Nexus 8 will fit my bike? Thanks for the info so far.

Every Formula Alloy hub I found was for a 135mm rear axle. The Nexus 8 hubs I found on Harris Cyclery measured to 130mm.

How to put a 130mm in a 135mm space is a mechanics question I am not sure about.

It may be just a matter of adding spacers. Does anyone know?

Bingo! Actually these hubs can be set up anywhere from 126 to 135 (if you leave off the not very good Roller brake.) I have one of mine at 126.

Sheldon "Nexi" Brown

http://sheldonbrown.org/raleigh-inte...int-nexus1.jpg
Click for details

http://sheldonbrown.org/iro/584/images/11.jpg
Click for details

Sheldon "Neck's Us" Brown

The mechanic should be able to confirm the fit. I've seen a variety of spacers for different drop out types, so I would expect it can be done easily.

I bought a bike with a stock Nexus8, and have been commuting on it daily since October/November. Here's my $0.02:

• Maintenance is a matter of changing the oil/fluid once a year, and infrequent adjustments to the cable. The hub has some yellow lines that must be aligned while in 4th gear for all to work well. Takes about 3 minutes with no tools. It's almost dangerous to ride it out of adjustment, as the cranks can spin free or hit a higher/lower gear randomly.
• Even when all is adjusted correctly, shifting to a lower gear is delayed when under a load and you have to let off for the hub to let go of the higher gear and down shift. You kind of get used to it. For normal, flat riding, it works really well. Climbing hills is where things act up.
• In cold weather (<20F), the shift arm on the hub sticks and won't go below about 3rd or 4th gear. The cable will slack up, but the shift arm needs a push to go lower. Since mine has a full chain guard and the arm is covered, I just hammer up the hills in 3rd, 4th, or whatever I can get.
• It is an event to take the rear wheel off. You get faster at it, but the other day I just rode my summer bike instead of putting a new tube in the rear after a valve problem. I put Mr. Tuffy tire liners under my studded tires to over-insure for winter flats, cause I'd probably die of hypothermia before I'd get it changed on the road.
• It is heavy. Not really a problem when you're riding, especially commuting with a load anyway, but when you try to hang it on the garage wall, you notice.
• There is a little drag in the hub compared to a chainwheel/cog combo. It's like a little auto transmission inside, so there are more intermediate gears and more friction. I often found 5th gear preferable to 4th because it seems to be more of a direct drive. This issue has either decreased with use, or I just got stronger and don't notice any more.

All that said, I wouldn't give it up, because it's caked with salt and I don't care. No cleaning. Just a bi-weekly removal of the chain case and lube with wet. All the perks advertised are true (shift while stopped, low maintenance, same or better gear ratios than most derailleur setups, etc.), and the premium (aka red band) Nexus8 might just fix some of my complaints. In your situation, I'd say a Nexus8 makes a lot of sense. Maybe add some flat protection to the rear, and enjoy.

I'm not even going to try to comment on the technical aspects of the Nexus hub, conversions, etc. I have a Breezer with the premium (red band) Nexus 8, which did not come with a coaster brake, and I love it. I do not own a car, and this is my only bike. I use it for daily commuting and utility cycling in an area with many moderate and a few evil hills. It's fine in all the conditions I have encountered. In the 11 months I have had the bike, I've only had to have it adjusted once. I don't know how to do that myself yet, but I'm working on it. :o I find it frustrating that there is very little in the common general bike repair manuals about Nexus hubs, but the wonderful Sheldon Brown has as much about them on his website as can be found. Someone once told me that in many ways you can just follow the general maintenance advice that is available for single speeds.

I tried out bikes with the premium Nexus 8 and the regular, and I found there was a noticable difference between the 2. The premium seemed smoother when shifting - just a nicer ride overall. I'm sure someone with more technical knowledge than I could explain why. As to the gearing, I have an 18T rear cog, and in nearly a year of daily riding, I haven't yet "outgrown" it. It's nice to know that I have other cog options if I do find my physical ability surpassing the current gear ratio.

It has been pleasant in this PNW winter to not have to do much drivetrain cleaning and maintenance. My poor housemate is always doing something to her derailleur. I think I cleaned mine maybe 3 times between October and two weeks ago. :D

Drivetrain Cleaning? Whatz dat?
Oh, I know, Spring rains. And a squirt of Silicone spray every other month or so.
I change the chain about once a year on my regular commuter with Sachs 7 speed hub, estimated 5,000 miles. Costs about $5. Seems a lot easier and cleaner than frequently monkeying around with a dirty chain.

The nexus 8 speed hubs do not run in a oil or fluid bath. Therefore you do not change the oil/fluid. They operate with a coating off grease slathed on them. The hub has to be dismantled, cleaned, regreased with fresh grease, then reassembled. They might need to be serviced more than once a year especially if operated in a cold or wet climate. When moving the bike from a warm house or garage to the outside when it is cold will cause water to condensate inside the hub. Which will erode the greases ability to lubricate thus creating the need to service more often.

I know, ILTB, but remember these 3 things:

1) I'm a girl. I like to see my bike pretty and shiny sometimes. :D

2) I take that pretty bike into offices not my own when I have to go to meetings. I do not want any of my sister office managers frowning at me bringing a dirty bike into their space. I'm the only one who rides to meetings at our agency, and I want to pave a smooth path for others. :)

3) When there's snow and ice, they "sand" the roads here. The sand is actually this coarse gravelly stuff that even affected the shifting of my Nexus 8. At the very least, it is a good idea around here to do a thorough cleaning of the drivetrain after they sweep the gravel up. I did check the chain to see if it was ready for replacement before I cleaned, but it's still in really good shape. I'm on my bike every day, but not the kind of high mileage that you do. Most of the places I need to go are close together. I suspect I'll be getting a lot of life out of my chains unless I start working someplace farther away.

Online service manual for nexus 8 from Sheldon's site.

http://www.sheldonbrown.com/nexus8/index.htm

I have seen a video of the teardown/reassemble procedure on the net, but I can't find it today.

Well the first two items do not apply to me. I leave my bike outside at work and for shopping, and in my garage at home.
The road crews use sand and God knows what else for the roads here, but it does beat riding on ice. if I ignore it it will go away eventually or when I change the chain, whichever comes first.

Tell the truth. When did you ever see a prettier bike than this?

#1--how do you guys stand to have dirty drivetrains? Shiny and pretty is good!
#3--that's why the stuff is called 'grit' in the UK. There's no sanders in the UK, but there are gritters :D .

Nasty stuff. Don't know about Portland, but King County has been rather lax at cleaning up the mountains of the stuff on my local roads :mad: .

Oh sorry! I didn't mean to hijack...

East Hill

My Nexus 7 has never needed to be disassembled or serviced in any way in the four years I've owned it. Nor have any of the Sachs 3, 5 and 7 speed hubs on my fleet in six or seven years of use. All are Coaster brake models.

Chainguards are good!

:D . Good point.

East Hill

i've have a nexus8 on my flatbar crosscheck commuter for 3 months now and am very pleased with it. Legot hit on all the weaknesses of the hub but one: sometimes i want a gear jump that is more gradual than the nexux provides. that's a small weakness.
All of those minor annoyances aside, i am very pleased with the the hub and will not be changing it any time soon.

One thing to think about: with the crosscheck, i get sliding dropouts, does the ibex have this option or must you use a chain tensioner?

I am still new to a lot of this stuff. Sliding dropouts? I am not sure exactly what that means. Chain tensioner? Not sure on that either. Sorry. Hopefully someone here can help me.

I am not a technical expert, but in order to put an internal gearing hub on a bike frame, the dropouts have to be a certain kind, I think it's horizontal. This is because of chain tension. One workaround on a frame without horizontal dropouts is a "chain tensioner". This is about all I am capable of explaining. Hopefully, some more mechanically oriented poster will stop by this thread. :o

It's a lovely bike, really it is. I do prefer your daughter's red one, though. (I also know I'm not seeing any closeups of the grunge.) What can I say, I'm a girl... :)

That bike is amazing! What I like is the small enhancements you added. The frontwheel light setup is great for using the hub on more than one bike. You have an Ipod. Do you recommend headphones while riding? Has anyone ever done a century with the Nexus 8? Your bike is setup to do so. :rolleyes:

Dropouts are where the axle of the rear wheel attaches to the bike frame proper.
They come in several verities. Chain Tensioners, Horizontal dropouts, Sliding dropouts, Eccentric bottom brackets, all solve the same problem, they take up chain slack.
Vertical dropouts, the most common verity, do not allow the rear wheel to be moved aft. Chain slack must be dealt with a chain tensioner.

http://www.sheldonbrown.com/images/dropf-vert.gif
Vertical Dropout (dropout images from Sheldon Brown's web site, check out his definition here

Horizontal dropouts allow the rear wheel to be moved aft.
http://www.sheldonbrown.com/images/dropf-short.gif
Horizontal Dropout

Like a Horizontal, a sliding dropout allows the rear wheel aft movement, however it also has disk brake mounts, allowing the disk brake to stay aligned to its rotor.
http://www.silverfish-uk.com/cms-fil...doc_slider.jpg
Sliding dropout {image from silverfish-uk.com}

An EBB (eccentric bottom bracket) instead of moving the rear wheel aft, it moves the cranks forward.
http://www.tetcycles.com/Specials/tetss3.jpg
Eccentric Bottom Bracket {Tom Teesdale}


http://homepage.mac.com/awcg/.Pictur...Chain-line.jpg
Sorry about the crappy image, used my phone for the camera.
The chain tensioner I use is a little different than the norm. Mine has only one wheel. It functions fine for an internal hub or single speed, but would not work with a derailleur.

Another kind of dropout you may encounter is called a track dropout. http://www.sheldonbrown.com/images/dropf-sub.gif Technically they are referred to as "Track bike fork ends" and not dropouts.

http://www.w-racing.se/web-content/P...r-rl-2_new.jpg
The more common verity of chain tensioner.

Hope this is of some help,

--A

I am very proud of the headlight mount, glad you like it.

Do I recommend using an iPod while cycling? No, but I use mine all the time ;-)

I will mention that when I could still ride a bike, I rode with a very good rear-view mirror on my helmet.

Now that I'm on the trike, I don't wear a helmet anymore, but there's a built in mirror on the trike. I definitely wouldn't use the iPod without a mirror.

Sheldon "Cycling And Russian Opera Go So Well Together" Brown