Chalo wrote:
> Sheldon Brown wrote:
>
>>Chalo wrote:
>>
>>
>>>Confound it. True to clueless form, Shimano have dished up a
>>>heaping helping of asymmetrical flange offset on a hub that
>>>didn't need to have any.
>>
>>2.7 mm is a "heaping helping" of asymmetry? Most non-flip-flop
>>
>>>hubs have at least this much asymmetry.
>
>
> Ah, I looked at your photo of the hub without the roller brake or its
> fixing nut, and I saw a bunch of offset. But as installed, the offset
> is pretty reasonable.
>
> It does make me wonder why they wouldn't make it genuinely symmetrical
> for ease of wheelbuilding, though.
>
> I continue to be completely vexed by the Sturmey Archer gearhubs that
> build into dished wheels. I reckoned Shimano had given us another such
> abomination, but I was wrong.
>
>
>>>Another nugget on the towering mountain of reasons not to buy their
>>>****-- like I really needed another one.
>>
>>"****?" This is the best multi-speed hub you can buy for less than
>>$700! Sounds like predjudice to me.
>
>
> I beg to differ-- I have owned both Sachs/SRAM 7 speed hubs and Shimano
> 7-speed hubs, and the difference is astounding. SRAM S7 hubs give a
> wider range of gears
A bike with an Alivio group will have a wider range than a bike with
Dura-Ace. Does that mean Alivio is better than Dura-Ace?
The Sram 7-speed and the Nexus 8 speed have the same range.
Sram 39/16 gives 37.5 - 114.5 inches
Nexus 8 42/16 gives 37.4 - 114.5 inches with the same wheel size.
See:
http://sheldonbrown.com/gears/internal.html
The Sram is afflicted with some excessively large jumps in the middle
of its range. 4 - 5 is a whopping 24% jump, 65.8 to 81.6 inches in the
example shown. 3 - 4 isn't much better, 23.5% (53.3 to 65.8 inches)
The jumps on the Sram 7-speed, from bottom to top are:
19.3%, 19.1%, 23.5%, 24.0%, 19.4%, 17.6%
The worst jump on the Shimano is 5 - 6, 22.3% (70.0 - 86.7 in the
example listed.)
The jumps in the Nexus 8 are:
22.2%, 16.1%, 13.8%, 17.5% 22.3% 16.0% and 13.8%
These seem a lot friendlier to me.
> and a *much* smaller amount of drag,
That is not a universally held opinion. In any case, the 8-speed Nexus
is touted to be rather more efficient than the 7-speed.
I do own a Nexus 7, replaced a Sturmey-Archer FM 4 speed, and the Nexus
seemed noticeably easier rolling than the Sturmey.
> while seeming
> generally more rugged.
Some parts are, some parts aren't. Shimano's sheltered shift linkage
is very much less prone to damage than Sram's "clickbox" hanging off the
end of the axle.
I personally see no clear winner between the two 7-speed models, but 8
trumps 7.
> I have never heard of someone wearing out or
> overloading a Sachs or SRAM 7-speed hub, but I have heard direct
> accounts of Nexus hub failures (requiring gear body replacement) from
> local shop mechanics. My two Nexus 7 hubs are on small-wheeled art
> bikes that doesn't get very many miles, so I've not laid waste to them
> yet.
>
> When I ride my Nexus-7-hubbed bikes, I feel like I'm losing a whole
> gear ratio to system inefficiency.
On the "small wheeled art bikes?" Doesn't sound to me like a
particularly valid basis for comparison.
> Admittedly this is a tough thing to
> quantify, but I don't find my SRAM hubs to display any more noticeable
> drag than my derailleur bikes. They seem to drive at least as freely
> as my Rohloff hub.
>
> The Nexus 8 hub is going to have to be a *whole lot better* than the
> Nexus 7 before it can be considered equal to or better than the SRAM
> S7.
From what I hear, it is. Not only more efficient, but with better
shifting under load, and combining the nice gear spacing of the Shimano
7 with the overall range of the Sram 7.
> It doesn't have a wider overall range than the SRAM S7, and it
> obviously uses more sets of plantaries. The presence of a true 1:1
> ratio in the new Nexus hub bodes well, but I suspect that in the field
> it will prove to be a lesser product than the SRAM.
There are actually quite a few of them in the field...what's new is the
availability of loose hubs. The ones on the road came on complete
bikes...we sell several models with this hub. Everybody I've spoken to
who has bought one loves it.
I think you're a bit too quick to condemn a product that you evidently
haven't even tried, just on the basis of what you "suspect."
Sheldon "Hope To Get Mine On The Road Soon" Brown
+--------------------------------------------+
| Opinions founded on prejudice are always |
| sustained with the greatest violence. |
| --Hebrew Proverb |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
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