29er Crosscountry, what's the best configuration?

I’m planning on racing a little duathlon and a little triathlon this fall. Each will have 5 or 6 miles of crosscountry with a smattering of real MUni spots. (2 out of 6 miles are tricky, the rest is less technical)

I want to use my Yuni 29 cuz its faster in the flats

Nanoraptor 2.1 x 29
125 cranks
No brake

Should I put 150s on? or longer? This would make the uphills a bit easier and I think this helps on the downhills too??? Should I ride squishy, medium or hard PSI? I like squishy for 3" x 24 MUni. But the big ole MUni tire compresses evenly. The Nanoraptor tends to fold to one side…this is weird to the rider.

Any advice is appreciated. Tom.

I’ve never used 150’s on my 29-er but from what others have posted you’ll lose some speed.

On smooth trails I find that high tire pressure makes for a much better ride, but if some parts of your course are full on muni maybe it’s worth taking a pump and vary air pressure according to terrain.

Sorry I can’t be much help but at least it’ll bump the thread to the top and maybe someone with more experience can reply; I’d be interested myself in peoples experiences of 150’s on a 29-er as I’ve contemplated trying it myself.

i’d run up the pressure to about 65psi,you dont want a pinch flat in a race and on a 29er its a big possibilty since the rims are so skinny.

your tyre wont be rolling over at that pressure either,but watch for jagged rocks since the side walls are made so thin.(slice)

150’s are a good idea for offroad,and over all they are faster since its hard to maintain the top speed that 125’s give because the terrain is always changing in favor of more leverage on the wheel.(whew!)

150 is the limit i’d say anything longer would negate the advantage of the 29 inch wheel.

You’ll need to practise and find out, and you’ll need to know a bit about the course.

I ride a Coker on 150s, a 28 on 110s, and a 26 on 150s.

The Coker will roll up short hills which would stop the 26. However, if the hill’s too long for the Coker’s momentum to rush it up , then the 26 can usually plod and grind up. meanwhile, the 28 is so light that it will sometimes beat both the Coker and the 26 on a smooth hill, even though it has the shortest cranks and highest gear ratio.

So, long hills need long cranks; short hills can sometimes be ‘rushed’ with shorter cranks and more speed.

Downhill, there is no substitute for leverage. I think a good handle is worth 10% or so on your crank length.

I find 150s painfully slow on a 28. 125s are more fun, and 110s are best for general and road use. Try the 125s. There is no right answer, though, and there is no substitute for doing the miles.

Good luck.

Re: 29er Crosscountry, what’s the best configuration?

In article <jagur.sfg7o@timelimit.unicyclist.com>,
jagur <jagur.sfg7o@timelimit.unicyclist.com> wrote:
)
)i’d run up the pressure to about 65psi,you dont want a pinch flat in a
)race and on a 29er its a big possibilty since the rims are so skinny.

I don’t see why a skinny rim would be more likely to cause a pinch flat.
A pinch flat is caused when the tire pressure isn’t high enough to keep
the ground from contacting the rim–this is a function of air volume and
tire sidewall, not rim width.

At 190 pounds plus gear, I run my NanoRaptor at 40 psi off-road
without bottoming it out. When it goes below 40 I start to bottom it.
(See Nick Brazzi’s Moab video).

)150’s are a good idea for offroad,and over all they are faster since its
)hard to maintain the top speed that 125’s give because the terrain is
)always changing in favor of more leverage on the wheel.(whew!)
)
)150 is the limit i’d say anything longer would negate the advantage of
)the 29 inch wheel.

A 29er with 170s is much, much faster than a Gazz with 170s on smooth
trails and fire roads.
-Tom

Re: Re: 29er Crosscountry, what’s the best configuration?

hog wash,

take two wheels with the same psi in them,the thinner rim will drive through the middle of the tyre easier than a wider rim.

Re: 29er Crosscountry, what’s the best configuration?

In article <jagur.sfppg@timelimit.unicyclist.com>,
jagur <jagur.sfppg@timelimit.unicyclist.com> wrote:
)
)Tom Holub wrote:
)> *
)> I don’t see why a skinny rim would be more likely to cause a pinch
)> flat.
)> A pinch flat is caused when the tire pressure isn’t high enough to
)> keep
)> the ground from contacting the rim–this is a function of air volume
)> and
)> tire sidewall, not rim width.*
)hog wash,
)
)take two wheels with the same psi in them,the thinner rim will drive
)through the middle of the tyre easier than a wider rim.

Well, perhaps that’s true for fat enough tires, but you certainly don’t
have to run the NanoRaptor at 65psi to avoid pinch flats, even on Slickrock.
-Tom

I would choose 150s myself, since it’s much easier to accelerate when you’re getting pitched around on the bumps. I have used 125s offroad but it’s a lot of work trying to avoid UPDs.

You may also want to consider 150s with a 24x3 tire. I prefer that combo to anything with the 29" since it’s much better at dealing with the bumps. If you’re only going 5-6 miles the increased rolling resistance shouldn’t be a big problem.

Re: 29er Crosscountry, what’s the best configuration?

I also use a YUni 29er with Nanoraptors, KH seat (5kg/11lb). The Nanoraptor is surprising good off road even though it doesn’t look that aggressive. It’s also light and fast on road.

The 125mm is OK for smooth trails, but I find that once it starts getting bumpy, every bump that slows you down takes a lot more effort to accelerate back to speed. The 150mm allows you to power over the bumps. That said, I find that I save about about 3-4min per hour if I used the 125mm over smooth terrain. On rough (or more precisely, bumpy) terrain I may be up to 5min slower/hour on 125mm compared with the 150mm cranks because of the sluggish acceleration.

I like my presures about the same as MTB pressure- not too low as the Nanoraptor can track a little funny if it’s too soft.

In short- rough/bumpy/lumpy terrain: Go 150mm
Smooth/fast: Go 125mm

You don’t need a brake if you are racing- technical steep downhills may be just as fast to run down.

Be careful if you’re wearing baggy shorts- you can snag on the YUni fork and wipe out badly at high speed.

The 29’er is great for duathlon- I did one early this year and I must have passed half the MTBkers on the 40minute hillclimb- given the right gradient a unicycle is more efficient than a bike. Once I got to the run I was able to transition quickly because I didn’t need to change out of clipless pedals.

Keep it light and keep it fast :stuck_out_tongue:

Would 140’s gain a little more speed but offer enough torque for a some of the steeper sections?

I was surprised no one had commented on using 140’s for x-country.

Re: 29er Crosscountry, what’s the best configuration?

teachndad <teachndad.sg72l@timelimit.unicyclist.com> wrote in message news:<teachndad.sg72l@timelimit.unicyclist.com>…
> Would 140’s gain a little more speed but offer enough torque for a some
> of the steeper sections?
>
> I was surprised no one had commented on using 140’s for x-country.
>
> Rod Wylie--------------------------------------------


CUT THROUGH THE NEWSGROUP BS>>>>>>>>>>>>>JAGUR’S COMMENT
HERE------->thats because he asked about 150’s compared to 125’s…

(unicyclist.com is down so i Google)

All very good comments. Thanks.

As a result, I will likely go with 150s. The tire pressure will take some experimentation. I was surprised to hear of psi all the way up to 65. Seems like that would be quite hard. The little bumps tend to UPD me. But like I said, I will experiment with 65 (and 40) because they have been reccommended by those who have done before me.

:smiley:

I’d ride with 125s, most cross country mtb racing terrain isn’t difficult enough to warrant 150s for anything other than steep bits. If you’re racing you’ll run faster up anything you can’t ride up with 125s. Practice lots on 29er and you’ll be fine over bumpy stuff even with shorter cranks.

Don’t even think about 24x3 if you’re racing, they’re slow slow slow even if you don’t have mega cranks. 26x2.6 is okay, but a 29er really rules over all the super-fat muni tyres for almost any bike race.

Short cranks and big wheel make you much faster downhill until the point at which you don’t dare stay on, you can ride big bombholes on them and everything if you’re not a scaredycat like I am.

I think a 29er with micro cranks + brake would be good for races with sustained downhill as you can definately ride faster than you can run, but you do sometimes spin out without a brake.

Joe

Joe,

Have you ridden 29-er with both 125’s and 150’s, if so how much smoothness/speed is lost with the 150’s?

I’m quite surprised to find that I’m getting able to tackle some of the bumps and hills on my 29-er with 125’s that I was doing on the muni; my main difficulty is that I’m not happy about attempting uphill freemounts on it.

I’ve got a pair of 150’s ready to try but want to spend some more days pushing it with the 125’s so I’m just gathering opinions in the meantime.

Yep. I’ve ridden with 110s too, but I decided they were too bad for uphills and for long downhills.

Basically 150s make it like a fast muni. 125s make it like a very very fast muni with a bit less control.

I started on 110s on my 29er, so when I moved up to the 125s it felt incredibly easy to ride.

Joe

I gave it a try last night on the actual race course.

Over the years I’ve done this course many many on a MB and many times more
recently on my 24 x 3 MUni. I can MUni all but the absolute worst parts. Soft
and Smooth ride, but slow. The approx speed of a trail jogger.

I don’t have an airguage for this valve (presta I think–The non-standard US
version), so borrowed a nearby MBr’s pump/guage. I pumped up to 40 psi. Turns
out I had been riding in the mid 20s. This explains the folding tire problem
when coming off curbs or roots etc (and soft ride). At 40 psi the little bumps
were much more challenging. (And there are 1,000,000 little tufts of grass and
divots and roots and pockmarks and loopdiloos on the 6 mile course) Every
bump required concentration and recovery. I’m just not relaxed yet at that
pressure. Practice will help.

In the technical section (singletrack, switchbacks, trees, roots, up and
downhills) I must’ve UPDd 2 dozen times. Uphill rapidly becomes more and more
difficult with length of hill. All but the smallest roots took me down. (Strategy
during race is to anticipate this and hop off and run just before UPD)(UPD use
up an alarming amount of energy)

The last 40% of the race course comes out of the woods and is open
singletrack then gravel road. Here I flew. The 125s and the bigger wheel made up for
lost time. Didn’t pass any riders, but easily overtook several runners who had
passed me in the woods. (Sweet)

I was much more tired than my MUni rides because of trying to power up some
hills and slow myself on some downhills. MUCH more leg strength needed to crank
up a hill. But mostly tired from all those UPDs and remounts, I think.

However, I shaved 1/3 off my time around the course! No
question that the 29r is the choice for the race.

The 150s are ordered (from the carphone)(ain’t technology great?) and I might
try 35 psi to lessen some of the jarring. I think the 150s will give me more
torque for ups and braking torque for the downs. The 150/35 text run will be
after Monday (projected crank arrival day). I’ll let you know how it goes.

Okay. How many of us have uni.com on speed dial?:smiley:

By Jagur:

That was unpleasant.

i hate posting though the google newsgroup,but when unicyclist.com is down i have no choice.

it was unpleasant for me too.

Twice this past wknd I rode with the new 150s. System works just fine. They give me more uphill torque and more steady breaking without too much apparent loss of speed.

Even though my brain kept telling me I was going slower, the clock said I improved overall time. This must be because I stayed on the wheel longer overall. I definately had an easier time going downhill. And stayed on for all but the worst ups.

I haven’t “raced” on the thing yet. But it makes sense that I dismount at the right moment and run up the impossible spots rather than wear myself out.

I’m happy with things so far. If the course had less of the tough technical stuff, I’d probably leave the 125s on. But I think this uni now fits this course. :sunglasses: