Tjaardbreeuwer profile

Have you tried it with anything attached to the saddle? I run a tube and CO2 on my saddle rails, and my 170mm E13 post has a problem reaching full extension.

For road wheels/tires Silca has a fair bit of info on their blog (from when Josh Poertner was at Zipp actually) about vertical deformation of tires and rims.

That makes perfect sense.

A slacker bike with more trail will have a longer front Centre and wheelbase(all else being equal). So you don’t need extra reach to create a long wheeelbase for stability. The same goes for over the bars, the front wheel is already further out in front, so OTB is less likely, even with a shorter reach.

Finally, the longer front center reduces weight on the front wheel, compared to a bike with the same rear center and reach, but steeper head angle.

Thanks, I get it now!

Only question I have:  When you are talking about Seat angle actual, how do you account for the offset of most seat tubes from the bottom bracket?

I have the 24x2.8 Vee crown gem on my 8 year old’s Riprock 24, and they are tubeless. Set up just fine. I used them for winter, since the knobs where (just) big enough to screw Gripstuds into.

Their website says the skinwall version is not tubeless though, which is to bad, as Id like to get a 2.6 for the rear of her bike for summer (front suspension bike with DHF on the front wheel). The only 2.6 I can find is the skinwall, but maybe the 2.6 in regular casing will come onto the market in a bit, since they are listed as “new’.

It could also be worth trying to convert the 2.6 skinwall, using plenty of sealant. It worked on the stock High roller 2.8 on that bike.

LOL, I would(and probably have done) do the exact same thing!

@AJ Barlas said: “’I find this more important than reach, at least on its own.”

I think that is the key. Too many people look at just one or two dimensions and then complain that bikes don’t fit or feel the way they though they would based on that.

Unfortunate there are no shortcuts. If you want to be able to compare all bikes, you have to use multiple dimensions.

There is no single “one and done” number that will tell you everything

What I was talking about here was bikes with taller or shorter headtubes extending down, so with the same stack height.

Imagine for a second two rigid bikes with identical stack and reach:

One with a 27.5 wheel and one with a 29er wheel. The 29er would need a shorter head tube to keep the fit the same, since the crown of the fork is higher above the ground. 

Therefor the 29er would have a longer downtube, even though fit was identical.

That’s all I meant.

If you are comparing bikes with the same travel forks and wheel sizes, then yes, (effective) downtube length is an easy number to grab and compare.

I do not recommend paying attention to (listed) effective toptube.

Here is why:

First off, everyone should have their saddle set in a fore-aft position that works best for them. Not at the place where the bike designer happened to put it.

That means that you adjust your saddle position to the same spot on every bike (for a certain use and style of riding).

Let’s take two imaginary bikes, with identical front centers (stack and reach and head angle). One has a steep seat tube angle, one has a slack seat tube angle. Effective toptube will be much longer on the second bike. But when you buy either of the two bikes, you would adjust your saddle position so it ended up the same distance behind the bottom bracket. The seated reach to the bars would be identical.

The thing that is important is effective seat tube angle. To see whether it is at all possible to get your saddle in your preferred position. Unfortunately, it is impossible to calculate effective seat tube angle at your own saddle height, based off the info in a geometry chart.