simonsez

I keep reading that Stack & Reach measurements are a good barometer of how a bike will fit. I was curious about Head Tube length, it seems that this measurement is included in the Stack. So my question: are there any reasons I should pay attention to that measurement when comparing bikes?

I'm looking for the most upright position hence why I'm paying attention to the Stack.

Thanks!

Plainsman

In my experience, don't worry about the head tube height if you are going by stack anyway (unless you think a super tall head tube looks bad and are concerned about that). Something that is a little misleading about stack and reach though - make sure you are accurately factoring the head tube angle, number of spacers, and length of the stem. I think the Bar X and Y is every bit as important as stack and reach. You could have two bikes with identical stack, but one with a short stem/low rise and the other with a long stem and high rise. This can still greatly impact your contact points. Velologic has a good tool that allows you to compare frames and factor in spacers and stem length as well as angle.

Iride01 

Stack alone isn't the only thing to look at. You have to figure out where your hands are going to be on the bars when your butt is in the saddle. Not easy to do by the geometry specs given by some.

And don't rule out low stack altogether if you are able to try them in person. Some bikes come new with a lot of spacers under the stem just for those that don't want to be as low as can be. So one might have some shorter top tube, stem length, bar reach and seat tube angle that might let you sit more comfortably than a bike with higher stack.

tyrion

More or less. If you know the stack, head tube length doesn't give you much more useful information.

AnthonyG

Stack and Reach are standardised measurements within the cycling industry that are measured from the centre of the bottom bracket which removes a range of variables which makes a direct comparison possible.
Two bicycles could have exactly the same head tube length yet different bottom bracket heights, different head tube angles, different fork lengths and different wheels sizes that could lead to different Stack heights.

If what you want to do is compare two bikes fits to each other then this is where you do use Stack and you do also ignore head tube lengths.

tangerineowl

Yes; that is why comparing different bikes, the stack tells you the front end frame height.

Ideally you want to find a frame with enough stack so you don't have to run a bunch of spacers e.g. 30mm below the stem.

Stack and reach is the best place to start. From there you get into other things like bb drop, chainstay, trail, seat tube angle etc.

simonsez

Thank you for all who replied, your feedback definitely cleared up a few things for me.

So just so I'm clear, I understand that I can always play with stem lengths and angles when it comes to reaching the handlebars but the only way to "artificially raise" the Stack would be to use spacers correct?

AnthonyG

More or less correct. Nominally Stack and Reach are referring to the frames Stack and Reach which is measured from the centre of the BB to the centre of the top head tube race. You can then talk about handlebar Stack and Reach and I've even seen the point where the stem clamps on to the steerer tube being specified as a Stack and Reach point. Yes you can raise the Stack by using an adapter (or if you haven't cut the steerer tube you can leave it long and use a bunch of spacers) but take note that when you do this you will also be reducing the Reach because of the geometry involved. You can of course correct for this with a longer stem.

Iride01 

I just bought a Specialized Tarmac. When it came in and was built up, they put 30 mm of spacers under the stem. So that effectively makes takes it back into the realm of upright seating. At least for me it did. I've split the difference so far and have 15mm under the stem and 15mm over the stem. Might go lower yet. It's a comfortable bike... for me.

At some point in the future, when I'm certain of where I want the stem to be cut, it'll no longer be something that can be adjusted by stem height. There are adapters, I've never seen them first hand. I'd think a better way would be to buy a stem that has more rise or angle to it that will also give you higher handlebar position.

All my first post was trying to convey to you is if you can try a bike out in person, you shouldn't ignore any just based on stack. They might feel better for reasons other than stack. And because initially they have so many spacers under the stem, the factory spec for stack doesn't tell you anything for certain except how low you can go. Not how low it is.

If you do buy a new bike from a local shop, you might want to tell them to leave as much steerer tube as reasonable and safe. I don't know how standard the practice is of leaving a lot of space under the stem. Some might wack it to minimum when they build it out after it's shipped to them. I don't know though...... I just got my first new bike in 41 years a couple months ago.

fietsbob

Traditionally, for mechanics, the headset stack is the total height of all the headset parts,

excluding the parts of the cups that go inside the frames headtube.


Perhaps you want a new fork with an un cut steering tube?
On modern bikes that means a good sized collection of Spacers under the stem..
that can be done..




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