[email protected] wrote:
>
> What this bike needs to do:
> 1.) Go very, very far on paved roads or smooth dirt roads, comfortably
> (29" wheels, fattish tires)
> 2.) Go up steep, steep hills (27-speed gearing)
> 3.) Resist awful torque from me standing up in the saddle
> (stupid-strong bracket and cranks)
> 4.) Be fun to ride
>
> What it doesn't need to do:
> 1.) Win races
> 2.) Win beauty contests
> 3.) Disappoint me in the long or short term
>
> I'm thinking Surly Karate Monkey (22 or 24" size?), rigid KM fork,
> tough 29" wheels handbuilt at LBS.
>
> What do y'all recommend for drivetrain, brakes, other components?
>
> Budget for complete Bike ~$2K-$2.5K
If you don't want to use 700x50 tires or larger, don't get a Karate
Monkey. It's too compromised in too many respects to warrant owning,
if not for the ability to use giant tires. To me, "fattish tires"
means something less than what the KM is designed for. If you intend
to use tires smaller than 700x45, then a Surly Cross-Check or Long Haul
Trucker will handle better. (The structural weak point of all these
bikes is most likely the fork steerer; all of them have the same size
steerer, but the KM has a substantially longer lever with which to bend
it.)
If you /do/ want to use true 29er tires, then use Schwalbe Big Apple
700x60 slicks.
Also consider Kris Holm 29" mountain unicycle rims:
http://www.unicycle.com/shopping/shopexd.asp?id=805 These huge rims
allow fat tires to assume a much better, stabler shape than when they
are mounted on rims intended for tires half as wide. Even a guy your
size could probably run 700x60 Big Apples on these rims at 35psi with
no problems. However, if you use a 38mm wide rim like this, it will
rule out the use of tires narrower than about 700x40.
A distant second strongest rim for 700c is probably the Sun Rhyno Lite,
and you can use tires as narrow as 32mm on it. Rhyno Lites are
available in 48 hole versions, and that would be a very good idea for a
rear wheel for you. Diatech make a good 48 hole disc brake cassette
hub that doesn't cost too much. Keep in mind that 26" wheels are
stronger than 29" simply by virtue of their smaller diameter. The
bigger wheel must be made from stronger components if it is to equal
the strength of the smaller wheel.
8- or 9-speed rear gearing is a mixed blessing to big fellas like us (I
measure 6'8" and about 375 lbs.) On one hand it allows us to climb
terrible grades without trashing our knees or pooping out partway up.
On the other hand, it requires radical dishing of the rear wheel,
undermining the wheel's strength when it should be as strong as
possible for our purposes. Disc brake hubs tend to be less dished than
non-disc hubs, so this is a good thing to seek out even if you don't
intend to use disc brakes. 7-speed freewheel hubs are an improvement
if you get one with a beefy axle, like Bullseye or Phil Wood.
Internally geared hubs are best; all modern gearhubs are dishless or
nearly so.
Rohloff's Speedhub 14 is the best gearhub, and offers overall range
equal to 24- or 27-speed MTBs-- but it is expensive at roughly $1000.
You can get it with a disc brake. The other drawback of the Rohloff
hub is that it only comes with 32 hole drilling. Rohloff claim that 32
spokes on a dishless hub make a stronger wheel than 48 spokes on a
dished hub, and they are probably right-- but when strength is
paramount, higher spoke count is better, all else equal. I retrofitted
my Rohloff for 48 spokes in a crow's foot lacing pattern, but such
machining is beyond the ability of a normal bike shop.
SRAM and Shimano offer 7,8,and 9-speed gearhubs for much less money
(like $200 and up), but they would require some front gearing to get
the range you're after. The anti-torque washers that come with SRAM
and Shimano hubs are not really suitable for a 300-pounder riding hard
on 29" wheels. That's sort of a worst-case scenario with regard to
drivertrain torque. It would be a good idea to use two tabbed washers,
one on each side of the axle.
I highly recommend BMX 3-piece cranks (e.g. Odyssey Wombolt, Redline
Flight, Primo Powerbite) with a triple adapter spider if necessary.
They are an order of magnitude stiffer and quite a bit stronger than
MTB cranks from Shimano, Race Face, FSA, etc. BMX cranks are usually
adjustable for chainline and tread width, whereas road and MTB cranks
almost never are. Shimano Saint cranks seem like a decent option from
a structural standpoint, but they are corny-looking to my eyes.
Chalo Colina
