mdilthey

Ditto. The 3.8" Surly Knard tire makes a fantastic touring tire... it's cheap for a fatbike tire, it has a fast-rolling tread, it's wide and fat, and the profile is great for those annoying paved sections. On a 65mm rim, it's fat but it's not "unreasonable."

Inertiaman

I'm not advocating that our dear friend @willibrord pursue a Pugsley for the BD, but I think this subjective debate over the "fit" of 27.5x3 wheels on a Pugs is unnecessary and misleading. The math is pretty objective. Its simply a matter of BB drop, no?

So a Pugs has a BB drop of 55mm. The "perfect" bike for the BD according to the route originators is the Advocate Hayduke, with a BB drop of 60mm. So if all else were assumed equal (same tires, same PSI), there is no geometric argument that a Pugs will suffer more pedal strikes than the holy Hayduke. In fact, its 5mm less likely.

If @willibrord is prepared/capable of riding the BD (and most of the evidence on this thread suggests otherwise) but faces the sole obstacle of lacking a suitable bike, there are multiple sub-$1000 options out there that would likely see him through just fine. The Growler Charlie at Performancebike.com for example: $799 w/ 27.5x3 and a Rockshox suspension fork. Needs some tweaks before embarking (tubeless conversion) but would probably last the trip. Or the Charge Cooker Midi series. Or leftover Marin Pine Mountain 1 models.

Inertiaman

Also worth noting that Surly's dedicated 27.5+ bike, the new 2017 Karate Monkey, has the exact same 55mm BB drop as the Pugsley.

The 2017 KM would be a good inexpensive choice for the BD but unfortunately not available until early February in shops.

nickw

This makes sense to me. I'm lost though, isn't an old pugsley 26"? If 27.5 wheels are used, you increasing BB height no? What am I missing?

Also, 55mm is fairly high, even for MTB. The new Cannondale mtb's are 62mm FWIW.

Leebo

The 26 x4" and a 27.5 x 3" rim/tires are similar in diameter.

Inertiaman

Pugsley is 26" yes, but 26x4 not 26x2.4, so a lower BB than typical 26" bikes due to larger effective wheel diameter. If you look at something like a Surly 1x1 (nominally for 26x2.4) it has 40mm BB drop.

chrisx

How high is the top of the tire from the ground? If a 27.5 tire stands 27.5 inches tall, and a 29 inch tire stands 29 inchs tall, than switching wheel size makes the tire bottom bracket closer to the ground. The bb still has a 55 mm drop. That drop is from axle to axle. Draw a straight line from the front axle to the back axle, measure the distance from the center of the bb to the line, and get the bb drop. Put on taller tires the bb gets higher off the ground. Put on shorter tires the bb and the pedals get closer to the ground. BB drop remains the same, distance from the ground changes with the tires. Google Baja 1,000 on youtube. How much clearance do you need down there. Why is the Baja 1,000 the place where they test the latest and greatest shocks?

UPS tracker shows my new tires out for delivery. My measurements say I can fit a 2.8 ranger on the front. They were out. So I ordered a 3.0 ranger and a 2.4 ardent. One tire or the other I am out of here. I have a 2.3 on the back. It is not the perfect Baja bike, I will make it anyway.

For our dear old friend @willibrord. Go for it. It is not a good adventure unless a guy in a funny hat tells you to turn back.

Inertiaman

Since we're all at a place called bike forums, I hope most of us already understand how BB drop is defined.

27.5 wheels aren't necessarily 27.5 in diameter. The tire cross section has a substantial impact. 27.5 is the approx. diameter of a nominal 27.5x2.1-ish tire. But on this thread we are primarily talking about 27.5x3 tires, which coincidentally are pretty close to 29x2.2 in outside diameter. So switching the wheels as you note above may not impact BB height at all. Indeed, this is the premise behind the wave of new bikes that are "27.5+/29 compatible."

For reference, some radius figures (approx. dimensions, as exact dims depend on specific tire brand/model and pressures):
-29x3 is ~385mm radius
-29x2.3 is ~365mm radius
-27.5x3 is ~ 360mm radius
-26x4 is ~ 365mm radius

My main point was to quantify the discussion of viability of 27.5x3 wheels/tires on a frame originally intended for 26x4 wheels/tires. As you can see from the dimensions above, the radius is nearly the same, so effective BB height is essentially unchanged. The slightly larger radius of 26x4 is typically cancelled by the slightly lower pressures typical of 4" tires (and hence higher compression of the tire cross section) such that the effective outer diameters are, for practical purposes, equal. Practically speaking, differences in specific tires and pressures will yield more distinctions than the generic dimensions will.

What BB height is "needed" in Baja? Now that is a subjective discussion. My point is that the BB height of a Pugsley with 27.5x3 is objectively 5mm higher than an Advocate Hayduke with the same wheels/tires. So categorically dismissing the viability of a Pugsley running 27.5x3 is subjective hyperbole contradicted by the objective math.

chrisx

The talk has been talked.
The typing has been typed.
Now it is time to ride the ride.

send back a few photos ayy?

willibrord

Wait, what?
The resident bike forum experts were wrong?
Will wonders never cease?

mstateglfr 

I havent figured out if you are just trolling or are overly opinionated while also being ignorant. I think its the second, but will enjoy figuring it out if you keep posting. Your posts are entertaining for sure.

willibrord

I might be opinionated but I don't attack the motives of those who presume to give me advice. Really I appreciate most of it but it is hard to sort through the contradictions.

chrisx

Baja is the place to excape all opinionated contradictions.
I am attempting to sort out a few last details. I found a slit in my stan´s rim tape, and need to find a new roll of it. My etrex is acting funny, or I did not press the right button, something. Maybe read the instructions.

Tubeless is important. With tubes I get about 4 punctures a day in Baja. Tubeless I get about 0 punctures a month down there. My 3.0 tire did not fit the fork. 2.8 would fit, but they are out of sock. So I am going 2.4 on the front and 2.3 on the back. I will be much happier when I get on the road, and away from the opinionated contradictions.

music from mexicali baja californis norte

mdilthey

I'll buy that, but math and tires are two words that never go together. The sidewall height of many of the 27.5+ tires is not all that high, and width and volume are similarly all over the map. There are 3.25 tires that measure out to 2.7 (I'm looking at you, Vee Rubber).

So, yes, the math works. Whether this translates to a practical bike is not something I am convinced of, since the 27.5+ topic came up three times in the last year and a half on MTBR.com and all three times, people were not happy with the conversion.

Maybe the strongest evidence is the utter lack of examples of anyone running a Pugsley like this.

I'll also concede that maybe I'm wrong, and maybe willibrod will be the first person to successfully drill a 27.5+ rim for the Pugsley offset, lace it up, successfully manage the BB height through tire choice and roll 2,000 miles to the end of the Baja Divide. I honestly hope this is the outcome if he wants to do that.

I don't have any agenda here other than to offer my best advice, and since I own a Pugsley, I can tell you my plans do not include 27.5+ conversions.

Inertiaman

As I stated in my original post, I'm not advocating that willibrod pursue the Pugsley. There is a long list of reasons not to, the offset/asym challenge among them, and more generally its sort of putting good money after bad. Better ways to spend money toward the objective.

I also made a disclaimer in my follow-up post that specific rim/tire combos will vary from the general radius figures I noted.

But you seem to be ignoring (or missing?) my main point, which is that the BB height is objectively *not* among the many reasons that willibord should avoid the 27.5+ Pugsley "solution", as you suggested in your earlier post. I'm simply pointing out that the BB drop on a Pugsley is identical to Surly's dedicated 27.5+ trail bike (2017 Karate Monkey), and actually 5mm higher than a widely well reviewed Hayduke, so the Pugsley BB height is not unsuited to 27.5+. This "math" is not influenced by the variability of real world tires sizes: for any given 27.5+ rim/tire, the Pugs BB will be identical in height to a 2017 KM with the same wheels.

Increased rock strike on a Pugsley may be due, in part, to the wider stance of the pedals given the wider BB and larger Q factor.

willibrord

Inertiaman is wise.

chrisx

Math or on the ground experience?
I will take on the ground experience.

The Katy trail is to frozen cold this time of year. That is why people are headed for Baja.

fietsbob

Things cool off at altitude there, like every where else, stay near sea Level..

mdilthey

Confirmation Bias

willibrord

You, I'm not so sure about.

DropBarFan

Perhaps though I'd reckon that folks stout enough to take on the Baja Divide trip probably can handle handle some cold temps too. BTW just now I'm a bit surprised to see that current sunlight length in Baja is only ~10% more than mid-latitude USA. Do riders use lights?

chrisx

How were you going to recharge the lights?

Daylight Hours Explorer

baja california january 2009




nov 2014

willibrord

Which is harder, Katy in winter or the Baja Divide?

chrisx

katy in January is colder than baja, much colder.
Above photos are at higher elevation than the offical route. I neglected to read the rules about finding my own route.
BCS is warm in winter

closer to the route

DropBarFan

Wow, didn't know it snowed in Baja. But for folks who can't manage a big trip down south, winter might be a good time to do local region trails if they don't have snow/ice. No worries about car traffic & more scenic/distant rides can be saved for warmer months.