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Top-6 OPEN U.P. questions

Gerard Vroomen - 22-Apr-2015
Last week we launched the new OPEN U.P. at SeaOtter. The launch was amazing, and that is saying something coming from a guy who normally dislikes shows and expos. I'll write a bit more about the event in a future blog, but today I just wanted to cover the six questions I was asked over and over at the expo. Clearly we didn't do a good job answering these six, so here we go:

1) What are the bosses on the toptube for?
There was no contest, this was the most frequently asked question by a country-mile. 
The answer is very simple; to put a small bag or tool kit on the toptube. This is already quite common on TT bikes, and we have used the same standard so you can fit existing toptube bags from Dark Speed Works or XLAB. I am pretty sure there will be a few bigger bags available soon, from the before-mentioned companies but hopefully also from a few other bag companies I admire, such as Banjo Brothers and Revelate Designs.

And no, the bolts don't have to stick out like that, you can put a small domed bolt in when you don't use them. We just put these big ones in so everybody would see them and boy, did they ever!

2) What's the thru-axle standard?
The U.P. is designed to expand your possibilities, not limit them. So we use the omni-present 142x12mm thru-axle standard in the rear. This means you can use your thru-axle mountain bike wheels in the U.P. without any problem. This is quite handy since the U.P. accepts both 700c (29er) wheels and 650b wheels, so chances are you have a mountain bike in one of those two sizes. To be clear, it will fit a 29er wheel with a cross or road tire, not with a mountain bike tire (see #3 for more on this).

In the front the thru-axle standard is 100x15mm, again the standard mountain bike size for optimal compatibility.

Aside from compatibility, these standards also provide the best stiffness. It is also for this reason that we did not adopt the new road thru-axle standards some companies are trying to promote. We honestly hope those efforts will fail, because they are monumentally stupid. Suggesting a 10mm rear and 12mm front axle as "optimal" for road is just nuts. You may save a few grams (or not) but you also lose stiffness and more importantly, you loose all compatibility that we spoke about before. Great for the industry (in a short-term, short-sighted way) that wants to sell you yet another wheelset, not good for you, for the bike's performance, for the environment or for the long-term viability of the industry.

Same goes for the new flat-mount disc brake standard, equally idiotic. What's wrong with post mounts? The flat-mount design puts the stresses in completely the wrong area, will require all sorts of adapters and in the end serves nobody other than the narrow interest of one company. In speaking with various brake makers, they say they will now produce all their brakes in post mount and in flat mount, PLUS an adapter to put a post mount brake on a flat mount frame AND an adapter to put a flat mount brake onto a post mount frame. Can you still follow?

3) So it fits 700c (29er) wheels with cross tires, why not fit a 29er mountain bike tire?
Let's start with the numbers; below is the outside radius for various wheel/tire combos. Logically, this radius is the height of the hub off the ground, so when this radius changes, so too does how high the bike sits. Keep in mind that the radius can vary slightly depending on the rim and tire model:

341mm - 700c/29er rim with 28mm road tire
344mm - 700c/29er rim with 32mm cross tire
345mm - 700c/29er rim with 35mm cross tire
350mm - 700c/29er rim with 40mm cross tire
342mm - 650b/27.5" rim with 2.1" mountain bike tire
347mm - 650b/27.5" rim with 2.25" mountain bike tire
365mm - 700c/29er rim with 2.25" mountain bike tire
368mm - 700c/29er rim with 2.25" mountain bike tire

As you can see, all tires have a radius within 9mm of each other, except for the 29er mountain bike tires which fall way outside of that. In other words, if you use 700c for the cross and road tires and 650b for the mountain bike tires, you will hardly notice a difference in geometry for the bike. But design a bike to combine road, cross and mountain bike tires all in 700c/29er format and your handling will be a total mess. That's why we designed the bike around 700c cross tires and 650b mountain bike tires and not 700c (29er) mountain bike tires.


There is a second reason. With all these wheels being roughly the same size, we can also use a relatively short chainstay of 420mm. Actually, that's a very short chainstay for such a bike, most gravel and cross have longer chainstays than that and can't fit anywhere the same size of tire. So by using 650bx2.1", we can offer the widest possible tire will keeping the chainstays short and performance-oriented.

4) What is the exact geometry?
This topic is worth a whole blog on its own, so that's the topic of my next one.

5) When will the fully be available?
As I mentioned before, we remain committed to the full suspension frame but we don't have a date for it. Right now it's a manufacturing challenge, a very nice one, but that means we can't possibly predict when it will be ready. When we do, you will all be the first to know (that is, if you subscribe to our newsletter. If you follow us on social media, you only have a 6% chance you'll see it because Twitter and Facebook like to make sure you don't see the updates from companies you follow unless we pay them for the pleasure to reach the people who have indicated they want to hear from us, but I digress. Anyway, you can on the right side of this page, a little bit up in the orange box)

6) Will OPEN make a road frame?
No. We're having too much fun off-pavement to even consider making a road bike.

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