I suspect that one of the reasons the SA 8 speed works well with small wheels is that they allow use of a sprocket input ratio that lowers the torque input level to the hub. With a normal 26" or 700C wheel the input ratio that would be used by many, large input sprocket and small chainring, subjects the hub to very high input torque levels.

Prior to the takeover of SA by Sunrace all SA gear hubs whose manuals I have downloaded listed a minimum input ratio of 2 to 1, that is the chainwheel with twice the teeth of the input sprocket. With standard size wheels, if followed with the SA 8 speed, this would give a low gear of 50+ gear inches and a high of 150+ gear inches, not satisfactory for normal uses.

Typical gearing on old 3 speed Raleighs was closer to 3 to 1, lowering input torque substantially. This, in part, might be one reason for the SA 3 speed hubs reputation for excellent reliability. Rohloff, SRAM and NuVinci still list minimum input ratios for their hubs. Rohloff is adamant about their recommendations, I presume due to it being marketed to strong athletic riders for MTB use as well as tandem riders. Most other gear hubs marketing seems aimed at casual and urban riders and bikes generally speaking.

Both my Swobo Dixon and Civia Hyland Rohloff came with the factories with gear ratios substantially above manufacturer listed minimums for the hubs. The iM9 has a factory suggested minimum input ratio of 1.73 to 1 while it is delivered with 19/38 gearing, giving a 2 to 1 ratio. The Rohloff has a minimum input ratio listed as 2.35 to 1 and the Civia comes with 16/45 gearing, giving a 2.81 to 1 input ratio. I thus expect both hubs to last a long time. In building my gear hub bikes I also follow recommended input ratio minimums when available.

Xcelite makes all kinds of tools. Your link is to a set of flush cutters. Yes, I imagine it would be easy to get the wheel off by cutting the shift cable, but I imagine maybe you had a different tool in mind.

What kind of tool did you have in mind?

I think he was being funny...

That said, if you don't have a roller or coaster brake on your Nexus, I've never understood the people that say they have a hard time with it.

Removing a coaster brake wheel isn't even that bad. It's the roller brake (more-so even than the competing drum brake hubs) that makes wheel removal take forever.

The first time for will always be tricky. And putting it back is also tricky the first time.

I think most of these things are actually advantages.
-Direct drive in low gear is good because it allows you to use a larger rear cog, which is more efficient and longer wearing. At the same time you can use a much smaller chainring, which is safer for your pants.
-If you have a hilly commute then the lower gears are the ones you will be in the most not the least. So you want it to be more efficient towards the bottom.
-The big jumps at the top and bottom are perfect because you usually only need the highest and lowest gears briefly for extreme situations; So there's no point having the second to lowest or second to highest gears be so close.

I'll give you that the shifting isn't ideal, but still way better and smoother than a derailleur. However, as mine has broken in over the years the shifting niggles have seemed to go away.

Overall I'm very happy with mine and if it were to break I'd buy a replacement instead of another hub like the nexus.

It is not that you can use a smaller chain ring, it is that you have no choice but to with this poorly designed hub that will only take an 23 and 25T cog. With other IGHs you are free to play with many combos of cog and CR.

If you live in a hilly area then you would especially want the low gears not to have big jumps. Ideally, you would want the gears to be spaced out evenly throughout and direct drive to be in the middle or upper middle. A 30% jump from 1st to 2nd and 7th to 8th is terrible since it wouldn't allow you to set up a good gear range on your bike. For example if you wanted to set up a bike for a hilly area you would choose a cog and CR combo that would give you around 80 odd gear inches for the top gear and 20 odd at the bottom and on a full sized bike that would be impossible to do with this hub unless you get a cog and CR that have about the same amount of teeth. And if you live in a hilly area than this is the worst hub since you have to stop pedaling to shift while going up hill and down. I know, I live in a hilly area.


Shifting is not better than a dérailleur since you with a dérailleur you can and actually can only shift while pedaling.


You get what you pay for. There is a reason why the SA XRF8 is much less expensive than other 8 (and 7) speed IGHs. If they were good then you would see them everywhere but instead of just on less expensive bike.

If you're happy with it than good for you. You are probably on a folder I assume.

I note that the Nexus7 appears to currently be a best buy. Bikeparts.com lists it for $136 + shipping and Niagara has it listed on Amazon for only a few bucks more. The listings indicate that it is a full kit with everything except the shifter & optional roller brake. Looks like a reasonably good buy to me. Both listings note it is the SG-7R46 model, roller brake compatible. A check of the Shimano Europe web site shows that this is the current model that they list.

That hub is pretty good. Always remember that if you are putting that hub on a bike with vertical drop outs you must use special shimano ant-rotational washers.

That is the one used on the Redline R530...which I just happen to have They must have been aiming for a price point. So far no complaints with the hub or much else on the bike.

Aaron

The gearing actually makes a fair amount of sense. The middle 6 gears are spaced closely together, 1st is bailout for climbing, and as it is direct drive, it is most efficient. 8th is for downhills or tailwinds.

If the XRK8W corrects the prior hub's issues with adjustment sensitivity, seals, and robustness, it should be an overall winner.

And again, as mentioned earlier, a 19t sprocket is also available, but not in a dished variant.

If the new (W) version is as good as it needs to be, coupled with 30t cranksets for 700c and 33t cranksets for 26" wheels, it could be a decent hub with the 25t sprocket.

BTW, it looks like the new (W) series is about 30% more expensive, so some of the cost advantage is going away.

Use of an IGH with vertical dropouts also normally requires use of a chain tensioner too, the reason I do not personally favor choosing such a frame for gear hub installation. The exception is a frame such as the Civia Hyland which has bolt on semi vertical dropouts but tensions the chain via horizontal dropout adjustment. Another option for chain tensioning with vertical dropouts is an eccentric bottom bracket as is done by Thorn cycles in England. I believe the frame needs to be specifically designed to take advantage of that method however.

The Civia offers 3 interchangeable bolt on dropout designs; one for the Rohloff IGH, one for the Shimano Alfine IGH and one for rear derailleur mounting. SRAM now lists anti rotation washers to fit the Rohloff standard dropout angle too for use with the iM9.

Decent maybe but not as good as a Shimano or Sram that has way more gearing possibilities and if you still have completely stop pedaling with the new model then there is no point.

So what if you live in a place with no hills or much wind? It is better not to have to settle for a hub with a bailout gear just for climbing and one just for tailwinds. It is better to have more evenly spaced gears that makes sense for any environment or situation.

There is no point in fitting a 19T cog since the 25 already makes the gearing too high for anything but a folding bike.

If they are going to make it the price competitive with Shimano and Sram then lower-end bike companies will start selling their bikes with Shimano and Sram hubs which are better known and better respected brands.

tatfiend,

Another option if you upgrading a bike with vertical dropouts is to use the original rear dérailleur as the chain tensioner as I did with mine.

Notice that even with the current Sturmey 8, you don't have to stop pedaling to shift. As with most IGH hubs, you just reduce pressure on the pedals a bit. Shifts on a properly adjusted Sturmey 8 are an improvement over Sram 5/7 and Sturmey/Sram/Shimano 3. It is not quite as smooth-shifting as Nexus 8 or especially Alfine, but then again, nothing is smoother shifting than Alfine.

What Sturmey has as an advantage is its performance for small wheel bikes and that the gears that matter in hillier areas (bottom gears) are the most efficient. Yes, to get the gearing right, the use of a small front chainring is necessary with normal sized wheels. The Nexus is backwards in that the bottom gears are least efficient and gears 5-7 are the most efficient.

Both hubs have their place in the market. Sturmey really did have some flaws with the first 8 speed hub, no doubt, which made the hub "not ready" for nearly all users. If they are fixed with the new model, the design itself is has legitimate benefits.

Maybe you can somehow magically make it shift while pedaling, I sure can't. If you read other reviews of that hub here you will see that seems to be the biggest issue. Even the owners manual specifically says that in order to shift you have to completely stop pedaling.

You do not have to ease up on the pressure to shift a Shimano Nexus or Alfine.

If you're happy with this hub then I am happy for you. I however, do not recommend this hub after riding on it for over a year.

[QUOTE=NEXUS;8363076]tatfiend,

Another option if you upgrading a bike with vertical dropouts is to use the original rear dérailleur as the chain tensioner as I did with mine.QUOTE]

I was thinking of a chain tensioner or derailleur used as a tensioner when I wrote the post, just did not mention the derailleur used as a tensioner option.

I personally prefer to avoid using frames which require a chain tensioner of any kind for IGH installation as I do not care for the appearance.

The springs in the XRF-8 hub push it into 8th gear; the shifter cable pulls it down to the gear you want. Since it's the hub spring that does the work in an upshift, upshifts under load can be unpredictable, especially in the lower part of the range (it may slip into 1st momentarily, or it may not shift at all until you relax a bit, or it may work fine). This tends not to be a problem for me because I only upshift when I need a higher gear, which happens when I'm spinning my pedals very fast and therefore can't put a whole lot of pressure on them. Downshifting under load, where the shift cable does the work, is much more predictable, though it will be harder to turn the shifter.

Remember, my point was that the XRF-8 hub is best suited to small wheels, i.e. 16" (and yes, you nailed it: I ride a Downtube Mini, among other things). Perhaps this harmonious match of hub to wheel size, promoting efficient high-cadence pedaling, is the very magic that makes mine shift better than yours.

True; and though I'm sure there is a reason for that, I should point out there are numerous errors in that manual, especially in the section about disassembling and reassembling the hub.

I agree that Nexus shifting is more comfortable in the hand; it takes less strength to move the shifter. But mine often slips when I'm downshifting, which is annoying because it can mean losing precious momentum at precisely the wrong moment.

In my experience, all IG hubs shift best under no load. Under hard pedalling, both Nexus Inter-4 and Nexus inter-88, as well as AW and XRF-8 can slip; Rohloff can jam momentarily; and the NuVinci shifter is hard to move. I can't say whether Nexus 8 or XRF-8 is better in this regard.

Yes, thanks, I think we've understood that.

I've given it some consideration and decided I'm changing my old Vitus road frame over to an IGH.

I took it to Rain City Bikes for the work.

here's what it looked like when I took it in



and when I get it back, I'll post the change.

The SA 3 speed has had an incredibly long production run that continues to this day and Sun has addressed the issue of the hub to slip into neutral between 2nd and 3rd and has eliminated the hubs propensity to skip under hard loads.

The SA AW hubs of the late 40's and 50's were exceptional and after that their quality dropped off but even then, an SA AW will easily run for tens of thousands of miles with no complaints and this is their greatest virtue.

The Nexus 8 has not impressed me due to it's sealing issues and word from some shops is that their service life has been 10,000 miles and thattheir performance deteriorates long before this mileage is reached. The Girl just had a get a new rear wheel for her bike as the Nexus 8 had reached the end of it's life at perhaps 10,000 miles.

I know one shop here that discourages using the Nexus 8 as a choice for custom built wheels due to their problems.

I have seen few issues with the Nexus 7 hubs and the Alfine is much improved.

I plan on setting up another SA AW with a dual drive as this offers a very nice gear range, moderate jumps, and is still simple and bombproof.

After that... a Nuvinci is high on my wish list.

I got it back. Here's what it looks like



I went with a Nexus 8. I had to switch to a flat bar because I couldn't get a shifter to fit my drops. I also switched to a single chainring crank and am trying a different set of fenders.

Can't wait to take it for a ride.

closetbiker;

Unless your drops were an oddball size the Jtek bar end shifter should have been a useable option. I have one on a Nitto Randonneur bar on my Alfine hub drop bar bike and it works very well. The Jtek fits over the end of standard diameter road drop bars so will fit even the thick walled ones.

Yeah, I know there are several options out there and I even sent in an email from a site that had what looked to me a pretty good set-up



but in the end, the mechanic said he had a hard time finding a supplier to provide him with these options and truth be be told, I don't really have anything against straight bars and I like the grip shift.



The bars, shifters and brake levers were extremely reasonable and if I find that I really prefer drops, I can always track down these shifters and switch back.

here's a question.

How often do the bearings on a Nexus hub have to be regreased (if they have to be greased at all)?

My old hubs had a re-packing about once a year, but aren't the Nexus bearings sealed and do not require annual re-packing?

I have one of the later Nexus hubs, the 8R35. It is very well sealed, I used it all winter long in Chicago. Rode through the slop, hosed it down, still worked at -18*F after all night cold soak. I think the latest Nexus hubs are very nice, same guys as the Alfine.

If you have an older, lower number Nexus, I'd run the oil bath and flush it once a year if it gets lots of bad weather miles. Every 2K~3K miles should be enough it it's a fair-weather bike.