irclean

So... I bought my new Alfine-equipped, belt-driven bike in late July. For the most part it has functioned flawlessly (as any $1000+ bicycle should, IMHO). The belt did slip off the cog while mashing up a hill shortly after purchase (see post #69 on page 3 of this thread if interested) and after a few adjustments it seemed that I'd solved the problem. Since the adjustment, however, I have been concerned that my belt tension was too tight despite assurances from the LBS that it was fine.

After reading a post from another Ceres owner I decided to back off the tension a smidge. After the first adjustment and test ride I noticed that the belt was starting to move off-track. I made another small adjustment and seemed to dial it in. Then came the acid test... I started to mash the pedals. Everything was fine for the first couple of tries, but on the third try the pedals gave way under my feet. I figured the belt had slipped off the cog again but when I looked down the belt line was fine. I tried pedaling again and, although there was some resistance, the hub wouldn't engage... nada through all the gears.

I took the bike inside and looked over the hub. The little yellow lines lined up in 4th gear as they should and I couldn't see anything obviously wrong with the hub, except for the fact that when I spun the crank, the rear cog also spun forward while the hub did not. Having no experience with IGH before this bike I am reluctant to touch anything on the hub and I am returning it to the LBS asap. Unfortunately, I have to work a 12-hour shift tomorrow and the LBS is closed Sundays and Mondays. Even worse, this is the week that they take off for Interbike in Vegas. It looks as if my nice, new bike may be sitting idle for a week or more while I wait for my LBS to accommodate me.

Anyway... are there any other Alfine users out there who have experienced a similar problem? If so, I'd sure like to hear from you. In the meantime I will be riding my Schwinn and thanking the Cycling Gods for N+1 (while cursing them under my breath at the same time).

canyoneagle

Bummer!
Please keep us posted. You might pop a message to the Yahoo IGH group (several members of that group are active in BF as well).

https://groups.yahoo.com/group/Geared_hub_bikes/

irclean

Well, I finally got my bike looked at by my LBS and it appears that I sheared off the rear cog's "tangs"; the little tabs that interface with the Alfine hub. Unlike my hybrid and MTB cassettes, there aren't 9 strong splines interfacing with the hub. Apparently my 295 lb. frame can generate enough torque to shear the aluminum tangs right off of the cog when hammering on the pedals.

The good news is that the bike is under warranty, so for one year I can go through as many cogs as needed. Better news is that there is nothing wrong with the pricey hub itself. The bad news, of course, is that the design is flawed and I may go through more cogs. In the meantime I guess I'll have to remain mindful of how much torque I generate. That's really gonna suck if I want to get out of the saddle for climbing or some quick acceleration; things I used to take for granted before my new bike.

In any case I still think I got the title of this thread right; this is a failure of the hub's design rather than the belt drive system. Hopefully the soon-to-be-released Alfine 11-speed has improved on this design. My LBS owner informed me that, while in Vegas for Interbike, he found out that someone (Phil Wood?) is working on a stronger replacement part for the Alfine 8. Hopefully it arrives before my warranty expires. Also at Interbike, Gates unveiled their next-generation belt drive system:

https://www.ecovelo.info/2010/09/15/gates-centertrack/
https://www.dirtragmag.com/images/int...80%94web-37-45

Arcanum

To be fair, I'm not sure a part failure when a 300 lb man is mashing the pedals on an up-slope is really a sign of a design flaw.

electrik

I have heard some whisperings about broken cogs and snapped belts... good news is that if you get annoyed you can just switch back to a chain.

Wiggles_dad

A good design should be able to handle this kind of torque.

soho2009

Might want your LBS talk to CERES or Gates and order the steel rear sprocket rather than the aluminum alloy. Plus the steel stop ring, and, if necessary, a compatible belt.

Its the new CDC system.

irclean

Granted... but I'm sure there are guys as big as or larger than me mashing pedals as we speak without suffering similar problems. In fact, there's an entire sub-forum here that's dedicated to them. Not to mention fully loaded touring rigs that are called upon to climb hills all day long. I don't know what to call it other than a design flaw. After all... no other bike that I'm currently riding, or that I've ever ridden, has displayed the same problem. BTW the cog failed while mashing on level ground in front of my house and I wasn't asking the cog to do anything I wouldn't ask any of the components on any of my bikes to do.

I'm not ready to give up just yet; I've read way more positive testimonials about belt drive than I have negative. Like many new technologies there are going to be some bugs to sort out. I'm sure the designers of the original dérailleurs also faced many hurdles getting their design to work.

irclean

Where did you glean that information? I see on the Gates Website that there are both CDX and CDC sprockets. I cannot find, however, what either acronym stands for nor what materials are used in their manufacture.

My LBS owner did talk to Norco (Ceres is the model name, BTW) and the rep he talked to warned that I might keep having this problem, being a bigger guy. I assume from that discussion that the replacement part they were planning to ship is an aluminum one. I was not aware that steel versions were available... thank you very much; I will be sure to mention this to the LBS tomorrow.

The LBS owner did mention that there may be a stronger cog available, but he could not remember if it was a Phil Wood rep he had talked to, or someone else. Perhaps he was referring to this. The website declares that the cog is machined out of steel and is available for the Nexus/Alfine hub.

Edit: I found some info on the CDC here. Like you said, the CDC system offers steel cogs. If I can secure one I'd say it's worth a shot, especially considering the fact that I'm far from a weight weenie who's concerned about a few extra grams. One other interesting fact from that article - apparently there are now 90 models from 24 different manufacturers using the Gates Carbon Belt Drive system. Looks like it's more than just a flash in the pan.

canyoneagle

Thanks for the update on this. I am no fan of the "3 spline" design for the alfine cog mounting.
I haven't encountered any issues with my drivetrain yet (other than your previously identified sensitivity of the belt-line to rear wheel alignment angle).

So far, I've been very impressed with the performance of the belt drive + Alfine combo, and I'll be sure to report here if anything does come up.

Thanks again for the update!

Mr IGH

I've never seen a 3 spline sprocket made of aluminum, interesting someone tried a belt cog in Al. The classic 3 spline is old but I've never seen a spline failure with the steel chain sprockets. The only issue I've seen is the c-clip coming loose, I always verify the clip is seated, grit can get in there and keep it from seating. I'm 50lbs lighter than OP, I run an Alfine on a mountain bike with 32x23 and climb hills until I stall out.

irclean

I just called my LBS and put in an order for the new CDC (steel) cog. Hopefully it stands up to abuse better than the CDX (aluminum) one. I guess I'm gonna have to treat it with some rustproofing to protect it from the elements, because it will see snow and ice duty this winter.

hartsu

No, Gates failure. And they already chance Alfine rear cog's design. Tabs are now steel.
I just install 22t rear sprocket and it looks like this.
Aluminum cog and steel insert.

Almost all coaster brake and Internally geared hubs use 3-tab spline pattern without problems.

ItsJustMe

I certainly do. Any mechanical part that can't take at least twice the expected maximum conditions is badly designed. Especially one that's likely to get someone KILLED. You could easily sheer the tangs off when hammering to try to get out of the way of a truck.

tcs

Yep. This 3-tab interface (in steel and for chains) has been an industry standard for over 60 years. Amazingly, Sturmey 1, 2, 3, 4, 5 & 7-spd, Shimano 1, 3, 4, 7 & 8-spd and SRAM (F&S) 1, 2, 3, 5 & 7-spd hubs all use these same cogs.

It would seem Gates erred when they blithely substituted aluminum for steel in their cog design.

modernjess

No problems so far with my Alfine 8, but it's a good old fashioned chain drive. I guess I could do a thread search for opinions or promotional information, but I don't get the allure of the belt drive.

electrik

Well, snapped chains and belts might be expected, but these are newer parts that are failing. More information to come i'm sure!

irclean

...And I don't get the resistance; it's almost as if some (not you, modernjess ) are hoping for it to fail so they can say their "I-told-you-sos". For me, a 2-minute test ride is all it took, and I was hooked. Same goes for the Alfine hub. I'm not naive enough to think that belt drive or IGH are going to faze out chains and dérailleurs anytime soon (or at all, for that matter), but I do believe we'll see more and more similar setups in the coming years, especially as the bugs get ironed out. I just makes sense; less mess, less maintenance, and less noise (which offsets the extra dough, but like any new technology it is likely to become cheaper as the years go by). Those who don't get it never will, and those of us who do don't care if they get it or not.

tatfiend 

The three tangs on the standard chain IGH cogs from all makers are steel as IMO they should be on the belt pulley that failed for the OP. The tangs are pretty small and thin to stand up to the cyclic torque of a rider, particularly a 295 pound one, if made of aluminum. I find it interesting that there have apparently been enough problems that Gates has changed the cog design per one post here but I am not surprised.

I do not call this a hub failure that can be blamed on Shimano but a case of an after market accessory that was inadequately engineered in the first place.

soho2009

Number of threads in this forum highlight the benefits/drawbacks of belt drive. So no need to tread the same path.

Then you get days like today where the rain/wind take moisture/particulate/large interfering particulate/road debris/tree parts to places chain drive bikes hate with a passion.

Meanwhile, I rode home within 5 minutes of my average time, parked the bike in the garage, and went in to the house for the night. I know that tomorrow, I will get out of bed and take a Saturday commute to the office with just a tire check.

No chain/derailleur clean up and relube, no brake adjustments.

As to the cog material - all you have to do is follow the path of the technology and you will see that aluminum cog made complete sense up to the point where Gates started getting feedback from their production runs for hub equipped computer bikes. There would be little to no chance that their research and life testing on the hub equipped commuter bikes would be "loaded" with large folks and their panniers going up hills mashing down and stressing the rear cog to the point where it failed.

Switching to steel is an appropriate and timely evolution of the technology as it crosses bicycle use into the commuter market.

soho2009

The steel is coated (I think) or galvanized. Its black and shows no sign that the elements will be an issue.

Hopefully this solves the problem(s). Just note, though, if you are regularing out of your saddle on hills then you might want to consider replacing the low gear or gears on the nexus 8 with gears that will get you up the hill in the saddle. Or you can wait a year when the alfine 11 comes to market and swap out the nexus 8 which I plan to do 2 years from now after Shimano has some production experience with make the alfine 11.

electrik

This sounds like your narrative only. What gates did or didn't do, as the case may be, is speculation. What is clear though is that they should have tested the cog and rated it for various loads - this cog system was designed for MTB use also, some of those riders are able to put large torque #s in. Though i haven't seen how the cog attaches in single-speed format, which is what is more common offroad, if that cog was changed good practices would have required new testing.

ItsJustMe

To me the allure of the belt drive is lack of maintenance. Lubricating and changing the chain is really the only thing I ever do to my bike on a regular basis. Other than that, I change the brake pads every fall, and switch to studded tires and back at either end of winter. And replace tires every few years. Chains are the only thing I have to deal with weekly. Belts have the promise of eliminating by far the most labor-intensive maintenance item.

And they're not greasy.

electrik

Indeed, the only reason i'm even interested in this is because the belt won't rust itself apart in the winter.... Saying that, the problem of the special frame and costs may keep me from switching. That and the teething troubles.

canyoneagle

+1
Belt drive on bicycles is a new application of a pretty solid technology (motorcycles, namely), and, as with any new application, there will be a few years of learning before they become more accepted/proven/refined. The aluminum cog tang issue is a great example of the learning process.
As the system becomes more refined and more common, I expect the "operating costs" (taking into account replacement over time) will fall more into line with conventional chain drive. I certainly do not see the belt replacing the chain, but it is a very appealing alternative for those of us who deal with snow, slush, mud and grit.

I'm one of the early adopters and am very pleased thus far - I do believe that the belt drive with an IGH offers a solid alternative to a chain drive with a fully enclosed chain case (and a superior option to an exposed drivetrain in the conditions mentioned above), particularly for commuting duty. I know I'm taking a risk by adopting so early on, and am now part of the experiment in progress.