The Bike Fitting Mega-Thread

I wasn’t really sure what to measure on the two so I measured the distance between the imaginary parallel line from the upright portion of the hood, along the centerline of the tops, to where it intersects with the horizontal center line of the deepest part of the drop (pardon my toddler level drawing skills)

For a sram red eTap axs shifter that distance is ~4.3 cm. For an ultegra mechanical 8600 that is 3.2cm. It’s nothing official but I guess it will have to do.

Anyone have ideas / calculator to adjust seat height for different Q-Factors? Right now my road bike and Stages SB20 have the exact same position - down to my ability using the VeloAngle, saddle, and pedals, but I get knee issues on the SB20. So I’m wondering if the slightly wider Q-Factor which effectively raises the saddle could be the issue.

Do you know the measurement difference in Q-Factor?

Can you describe the type and location of the knee pain?

Have you made any lateral adjustments to your cleats or are you using the same exact shoe/cleat setup on the different Q-F setups?

Assuming a standard Ultegra crank, Q factor is 146mm and @dcrainmaker has the SB20 at 157mm.

I’d experiment by pushing the cleats outboard, to bring the feet inboard but maintain the longitudinal and rotational position.

Could also try looking down when pedalling and see if the knee when at the top of the pedal stroke is tracking further out, maybe a video from the front on both setups to confirm.

A picture of the cleats and soles of the shoe showing current position would be interesting.

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Thanks for the Q-F info. It’s a notable difference.

To the original question, even at that stance width change (assuming the same shoe and cleat position) a change in effective saddle height would probably be just a few mm’s. I can run a triangle calculation estimate later, but if we assumed a right triangle with the angled hypotenuse with just 5.5mm short line would only be a few mm longer than the other straight line, at a typical saddle height of 700mm or more. Essentially, I don’t think saddle height is the issue here.

As mentioned above, I feel the key here is stance width. If at all possible, two pairs of shoes is best. That way you can make the ones on the wide Q-F setup with the cleats set wider which places the feet narrower.

Much of this depends on the current placement of your cleats on the shoes. But considering the Q-F delta, I don’t think it makes sense to use the same shoes and cleat position on both.

Right now I have one pair of road shoes that I use both on my road bike and the SB20. I’m getting another pair of shoes, so once those are setup I can setup the cleats on the SB20 shoes in the narrow Q-Factor position.

The pain is on the outside of the knee, and starts just below the knee cap and runs up the IT band - it’s a little worse today, even with no riding.

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Also, depending on what cleat system you are using, if you need to reduce the width more than the lateral cleat adjustment allows, there are these SQLab pedals that offer a 5mm narrower stance.

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Thanks for the suggestion, but I’m on Time pedals

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I believe this info is in the pro version of BikeCad

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  • Not conclusive, but this sure can be a result of a wider stance width.

Do a simple test with your feet flat on the floor, at a “normal” standing width for you. Then slightly wiggle your feet about the same 11mm [1/2"] wider and feel what you can tell around your knees. This widening along with the still “flat fee” as we get in clipless pedals can add tension to the outer part of our legs, tendons and muscles.

All that to try and demonstrate that wider stance might be the source of your pain. It will be interesting to hear what happens with your 2nd set of shoes and cleats setup with more narrow stance. Hoping it solves the issue, but be sure to report back.

Here’s a curious saddle height starting point question.

Let’s assume we are just going to start with the Lemond method to set our initial saddle height.

Okay, what happens when you have a bike with a 74 degree seat tube and another with a 73?

My understanding is that the initial saddle height is up the seat tube to the saddle intersection.

Would you set the initial saddle in the center of the seat tube and then set the height?

Since at 73, you’ll be sitting further back than at 74.

Just curious.

For those not aware, this method:

  1. Take your inseam length (feet in socks on the floor to crotch height) and multiply by 0.833.
  2. Use that value as the set distance between the center of the bottom bracket to the top of the saddle.

I can’t find hard info on the precise location set on the saddle, so I question

  • Is that distance is to the middle of the saddle length?
  • Or is that distance regardless of saddle length fore-aft position, measured thru the center of the seat tube?

Either of those will impact the end results. I consider setback a fairly personal thing and something that would only be impacted by a seat tube change if you are unable to reach a desired value as a result of limits on saddle fore-aft range in the rails, coupled with the setback value of the seat post.

I will add, that the Lemond method ignores at least 2 large variables:

  1. Actual bike crank length is ignored or assumed to be “normal” at 172.5mm? Either way, this could be a real issue for some riders with longer or shorter than “normal” cranks.
  2. This also ignores the true range of motion that each rider has in their pedaling. Ankle angle is the most visible one and not everyone “ankles” the same, so that should not be ignored.

Essentially, this like so many other “quick” methods has some issues and anyone using it should recognize it as a start only, not an end in most cases.

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@mcneese.chad

That’s why it’s more of a starting point. I’ve seen some fitters say take the rear of the saddle and measure 120mm from there to a point toward the nose. Use that as the measuring point.

This is all a starting point.

Hump

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Some saddle manufacturers apply a marker at a particular width, typically around 75 - 80mm. Selle and Pro being two.

The theory being that the width dictates where a rider naturally sits/slides back to.
Therefore the same position can be set both in terms of height and fore and aft regardless of saddle and seat angle. Points in space from the centre of the bottom bracket.

The Lemond formula also comes from an era when KOPS was considered important.

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I’m looking for some advice of people experienced with MTB fits and the more recent geometries.

I currently own a 2017 Cube LTD SL 29 in a size 17", with a 90mm -17 deg stem.
https://archiv.cube.eu/nl/2017/814001

Which has this geometry:

Now it’s looking like if I continue riding it all through winter, I’m going to have some serious expenses. Bottom bracket bearing, chain ring, cassette and chain have already been replaced. Head set as well. Unfortunately the bearings in the wheels are basically gone and in this case that means replacing the wheels. This frame still uses quick releases and is non-boost and so on so it is very difficult to still find a replacement wheelset and on top of that, likely this bike is only worth 650-700 Euros or so so spending >450 Euros on another wheelset also does not make much sense. It’s also not very futureproof since I can’t use these wheels on a new bike I might buy in the future.

That’s why I decided to look into getting another bike.

So far two have caught my attention, I can get a very good deal on a size M Superior Team Elite 29 which is brand new (2400 Euros), FSA Afterburner wheels, Full XT 1x12, Rockshox SID Ultimate fork, carbon seatpost and frame. Or a second hand size M Orbea Alma with XTR DI2 2x11, Fox 32 Stepcast, carbon wheels with DT350 hubs, carbon seat post,… For 1500 Euros. Both for sale at bike shops about an hours drive.

These however seem to all be 30-40mm longer with regards to reach but use 60-70mm stems. So since I’m using a 90mm stem it should be close but I’d still like some confirmation. Also with regards to how the handling would be with the longer bike but short stem…

These pictures might nog say much but hopefully they indicate how my position is right now. I’m mostly a roadie/TT’er so I still have the feeling I’m more upright but it’s a comfortable position for me to climb and descend in.


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Looking at new handlebars. My current handlebars have a reach of 70mm and I use a 110mm stem. The new handlebars I’m looking at have a reach of 80mm, to keep the position equal I would need to change to a 100mm stem right?

Yup.

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Replying to this generally to get @mcneese.chad’s take on something.

While manufacturers state their reaches in their product specifications, are there any particular brands of bars that you have found inaccurate and/or unreliable in their reach numbers? If so, do you find they under or over shoot their stated reach? Also, do you find that effective reach varies wildly, given where you set up the controls on particular bars (i.e., slightly angled up, versus a “flat transition” of some sort)??

You are opening the can of worms I deliberately ignored above :stuck_out_tongue:

Handlebar measurements are a bit of a mess if I am honest. I can’t point fingers to any brands as offenders, but mention that unless they provide clear drawings with related dimensions, you are in a bit of a crap shoot.

Some measure differently with center-center (my preference), but some measure to outside dimensions. Reach in particular is interesting since the actual curve can vary. Bend shape along with reach & drop dimension differences while having the same cen-cen reach value can actually lead to different hood position even if you match all the angles. We are talking millimeters different here generally, but it can mater more to some riders and cause confusion in general during setup.

Add in the use of Flare for some bars, and the water gets even muddier when selecting your width to start, along with the potential crossover to how that affects reach to a hood position.

I don’t have any great answer here other than to say that people should research into the fine details (as much as any maker offers at least) and try to measure closely with whatever they have on hand for comparison.

Thanks for the response. In fairness, I knew I was opening a can of worms, to see if you would take the bait… :wink:

The main reason I asked this question is that I recently slapped an older 3T bar I’ve owned for a while back on my bike due to some warranty issues with a damaged Zipp bar. The stated reach numbers were only 7mm apart, so I didn’t think I would have all that big of an issue. While it wasn’t catastrophic or anything, the effective reach was VASTLY different, with the 3T’s being effectively MUCH longer than an additional 7mm. Also, with the ends of the drops clocked to the same angle (perpendicular to the floor, or vertical) the area where I ended up mounting the hoods in order to get generally the same tilt was effectively much “lower” on the bar, resulting in a bit more drop than I had before.

Just thought it was worth highlighting how much bar shape and dimensions can affect fit and the effective riding position.

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