fietsbob

RTFM it said 13.6% increase where did your data come from ?

FBinNY 

I believe that he wasn't challenging the number, just the math implied when you equated going up and down by that amount. It's a classic numerator/denominator error, and happens every day.

For example, start at 100, subtract 10% and you're at 90, now add 10% an you're at 99. Where did the difference go?

So in bike tech, you need to be clear whether you're talking about percent increase steps going up, or percentage decrease stapes going down. Of course, since the steps are rarely uniform, the 13.6% figure may only be an average of steps that deviate from that on either side anyway.

fietsbob

Suppose get the gear tooth count for each if the 6 gear combinations* in the hub, are needed to really get anal about the math.

add the low range drop gear and calculate the sets again .. enjoy 1

* one combination directly drives the hub shell .

Banzai

Alright, re-ran the cable, continuous housing. So far, (just 3 miles of VERY easy riding), it is doing alright. A tiny bit of noise...could just a little bit of whatever the issue was before have already trashed the internals?

The cable housing might not have been the issue. It also seemed like the cable was snagging/catching on a little piece down at the hub.

For something marketed as bulletproof/reliable, even if this works from now on, it is definitely a VERY finicky system. I don't know that I would actually recommend it to anyone, but I'll keep riding it because of the cost and labor sunk into it. To do it again, at least right now, I would have kept my derailer system on there.

We'll see how it holds up on the next commute.

Reynolds 

OP, maybe you got a bad specimen. My Nexus 8 has 14000km trouble free kms on it, ran OK from day one.

Mark Kelly 

13th root of 5.26.

FB is right, I was just pointing out that your arithmetic was wrong.

Shahmatt

Unlike derailleurs, internal gear hubs operate on cable tension and so are very sensitive to it.

As mentioned before, my 7 speed hub had the same trouble, but I'd already done about 200km before fixing the problem. Since that time I've now done more than 1500km with no trouble at all. So IMO the Alfine, being the better quality hub, would likely be quite difficult to trash even if poorly calibrated. The noise may be because the hub is still new and some bits need to be broken in.

Glad the problem seems to be sorted. Enjoy the hub! Once you figure out the advantages it will change the way you ride, hopefully for the better.

Banzai

Er...cable tension is exactly how derailers operate. Except for Di2.

Shahmatt

Sorry you are right. I'd forgotten that a rear derailleur would cause the chain to slip to the smallest cog if tension was lost. IGHs do the same but are perhaps more sensitive to the tension.

fietsbob

Single Cable shift hubs are just like your indexed derailleurs/ lever detent spacing on the front .. the action of the gear change ib the back.

a Spring pulls the cable tension back the other way

2 cable , the other cable pulls back .. a broken cable does not force a gear change, then.
(8mm wrench directly on the end of the shaft , in R'off hubs is the back up shifter)

fietsbob

Originally Posted by fietsbob
RTFM it said 13.6% increase where did your data come from ?



I have no idea how you got there, or what that means... show your work.

tooth counts for all gear combinations would be a base.


yes not a math whiz . nor in the IT biz . at 67, I can figure out simple mechanics without seeing a video.

Wilfred Laurier

Actually, neither operate on cable tension. They both require precise cable position. The cable tension is determined by the return spring in the derailleur/hub, and could be higher or lower with no change in performance.

As for the OP's problems, I also think it is a bit premature to blame the product when he himself says he has no experience with it, and never got it to perform adequately from new. There have been a few reports of problems with these hubs, but they don't match the OP's description of the troubles. So either he has a unit with an uncommon defect (in a product where defects of any sort are quite rare), or he made (a) mistake(S) when installing it.

Mark Kelly 

I did, but I'll do it again for your sake, with supplementary notes:

5.26 is Rohloff's stated gear range, the thirteenth root is a necessary consequence of having 14 gears.

5.26 [SUP] 1/13 [/SUP] = 1.136 and 5.26 [SUP] -1/13 [/SUP] = 0.880, or 88%, not 86.4%

FBinNY 

I think my explanation and example were easier.

For Bob,

When comparing steps going up to steps going down, you can't simply subtract. When you're going up you're always multiplying from the lower step, each gear is 1.136% of the one below it.

But when going down. you're multiplying by a larger step, so if the step height is the same (as it has to be), the multiplier is smaller. Ie. each gear step is 12% lower or 88% of the one above.

So, if you start from which ever is direct drive, which we'll call a ratio of 1, the next step from that would be 1.136. However now that we're at 1.136, we can't subtract the same multiple because it'll be too much (1.136 x 1, and 1.136 x 1.136 obviously aren't equal), so we subtract 12% of 1.136 to get back to 1.

dbg

I've had excellent reliability from a half dozen nexus-7 builds (originally used by my kids, now distributed around the neighborhood). I commuted on a nexus-7 for several years until I noticed some freeze-up tendencies below minus 10. Probably cable related, but I switched to a nexus-4 and have never again experienced that freeze-up in 7 years. Nexus-4 was discontinued a while ago but I occasionally pick one up on ebay (Yo, stay away!). I find the nexus-4 to be perfect for my needs as a commuter. My wife has been using a nexus-8 for years. She complains of shifting problems when climbing -but I don't have any such problems. Pretty sure she's trying to shift under heavy load.

digibud

Friends of mine Road Alfine from southern tip of South America to Alaska. That's the limit of my knowledge .

Banzai

It would appear that the little corner that the cable had caught on might have been the issue. Barely perceptible; cable routing and wrap looked clean. Or it could have been the lack of full-length housing. Since I didn't control for variables, I'll never know. Aside from the noise - very subtle, but present nonetheless - it appears to be functioning.

Another point to consider; when calculating the weight that this system adds to your bike, don't forget to add in the weight for the 15mm wrench. I have a small Craftsman crescent wrench occupying room in the saddle bag on that bike now. Required, in the event of a flat.

Reynolds 

Weight in itself isn't too much, what I don't like is it's all concentrated at the rear hub.

Banzai

Very true. When the wheel was built, it was a bit surprising what a boat anchor that wheel felt like when holding it at the rim. Very dense concentration of weight.

Wilfred Laurier

Ironically, weight concentrated at the hub has less of the inertial effect of weight at the rim... the benefits of removing rotating weight are far greater at the rim than at the hub.

Reynolds 

It's not the inertial effect, the handling and feel are different than those of a derailleur bike. Still I like IGHs.

spectastic

yeah I can see how a bike would behave differently when you have most of your groupset concentrated in a 5 lbs rear wheel. maybe this can be mitigated by using a smaller frame and a longer stem, so that you can distribute your weight further forward. I can see this being a help for touring bikes that are rear heavy.

spectastic

it was mentioned that alfine 8 is not for the performance oriented riders. I am very much performance oriented, but I don't plan on racing on the alfine, just a little commuting, touring, maybe mountain biking. I've got the hub, but haven't put it together yet.

I've researched that the igh is about 5-8% less efficient than a clean derailleur system. this seems significant. how does it feel when it's broken in?

Reynolds 

Mine didn't need break in, always worked OK. As said before, I wouldn't use it for sport riding due to weight, handling and uneven gear spacing. It's Ok for commuting though, maybe the gear range is a bit short for super steep grades.

spectastic

but it's not that much heavier than a full derailleur drive train. it's just distributed differently in weight