The Bike Fitting Mega-Thread

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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Yup, it can be a proper mess. Mixing / swapping between old and new is a problem I have dealt with more than once. Many of the older bars were designed with the upper part of the drop bar to be level or downward pointing, while newer bars are flat to upward pointing generally speaking.

Using the lower part of the hood to match will commonly cause the issue you described, since the bars had different intentions and were aimed at different brake hood shapes as well. Mixing old/new bars/hoods can give some odd results and sounds similar to what you hit on.

Does anyone know of any open source spinscan software?

Cheers

No but it’s an intriguing question.

Spinscan was Computrainers/Racermate pedal efficiency visualisation software and can probably still be found online. There are similar visualisations in the Tacx Neo, Wattbike, bikefitting.com, Garmin pedalling dynamics etc software.

What hardware do you have that is capable of outputting this info that doesn’t already have it’s own proprietary version of Spinscan or metrics that indicate the pedalling efficiency?

Just trying to understand what you’d like to see and how you want to use it.

I have a wahoo kickr, various power meters, left and right side - Would like to see the monkey nut diagram really - trying to assess my power imbalances and torque/power effectiveness after injury. I want to compare between legs.

Well the Kickr doesn’t. What are the various power meters you have?

Also, if you didn’t test before your injury, how do you know any imbalance wasn’t already there ?

I’ve got my spinscan data from a bike fit before.

I have wahoo powerlinks, dual sided. 4iiii dual sided. and Quark.

If you can find someone with a Computrainer who would loan it to you or a bike fitter that uses it that would be the direct comparison. I have a couple, where are you based?

Failing that the 4iiii will have torque effectiveness, smoothness and balance giving you some insight or maybe go to a gym with a Wattbike and look at their PES.

Was hoping to get some input on my bike fit. Have never really found a saddle that I can sit on for 5+ hours without getting a saddle sore, so I wonder if it has something to do with my fit. In my most recent change, I’ve moved my saddle further back, and slightly up, in an attempt to get closer to a 30* knee angle. I’m wondering if I should move from 175mm cranks to 170mm to help keep my hips more open.

Ultimate goal with my fit is to get in the most powerful/efficient position, but also be comfortable enough to ride for 6hrs (biggest issue is saddle). I’m 6’4 and riding a Canyon Ultimate, XL frame size. After moving my saddle back, I feel like I barely have any weight on my hands. I felt stronger with my saddle slammed forward, but feel “smoother” with my saddle back like this.

Link to Video:

Thanks for the advice!!

What’s the best way to find a local bike fitter? I’ve tried Googling it but haven’t really found much. I have 3 shops that all do fittings, with prices from $125/hr to $200 per session. But hard to say which, if any, are worth it? Also curious what people thought about apps like My Velo Fit. Much cheaper so in my mind, much less of a gamble if it doesn’t work for me.

  • I’d suggest starting with a conversation directly with each fitter to understand their process and just get a feel for them.
  • Either from that fitter or by asking in your area, see if any local riders had fit and ask about their experience. Good, bad, worth it or not and such to see what people with live experience say.

The remote fit tools are interesting and I still need to give them a go. I think they hold a good chance of getting people close, but there are limits to what it can offer vs an in-person fit. Might be parallel to considering something like TR vs a real coach. There are interaction differences and potential depth of coverage of any issues.

As far as a gamble, mention that with each fitter and see how they handle any follow-up fits and adjustments. I offer at least one appointment after the initial one to rehash as needed. There are differences when fitting inside on a static setup vs real outside riding. Not to mention the magnitude of difference in setup can lead to things feeling odd for a while when heading outside. So a follow-up is good if included to address that type of issue.

An example of a coach/fitter that has a comprehensive set of services:

Includes a follow up and he will review outside on the bike if you join him on the warmup for one of his coached group rides.

Quick question, shopping for a tribike, i did a retul fit in september.
I’m 5’8"+ and ride a medium cannondale supersix evo (2015 model)
I have a short torso but long everything else (wink wink hello ladies) including a long femur

The fit put me on a small frame according to the fitter. With about (obviously i have a slew of other numbers)
Frame Stack 550 mm
Frame Reach 354 mm
They didn’t have models /brands i wanted so i started just looking at classifieds and lazily looking at new bikes that were out of my budget

Fast forward to december where i’ve been shopping a bit more actively to spend my xmas bonus on a new tribike
I find a small 2020 Argon18 e-117 frame at an LBS that has a big tri focus (half the bikes on the floor are tri bikes) put a deposit on it after seeing it in person but they “won’t let me pay fully or take the bike until i get a fit” which is totally fine. Come the day of the fit, the fitter changes a few things on the small frame and doesn’t like what he sees, low clearance of the knee to elbow pads and to reach the stack height a lot of spacers would have to be added and the seat would have to be pretty high, near max height, etc. Just a lot less options to “play” with the position
They didn’t have a medium frame, BUT they had a large 2021 frame in the same spec at the exact same price. He said, we can give it a try and worst case scenario go back to small.

The fit feels good and i end up going with that.
I’ve only ridden it on my rollers so far and it feels alright but can’t ride in aero on those yet as that’s a skill in itself , in your experience have you seen such jumps in sizes work in the long run?
I still haven’t put it on my DD trainer as i have to degrease/wax the chain before i do so.

TT/Tri bike sizing is a different beast compared to typical road bikes. The key elements are the Pad X/Y as measured from the bottom bracket. Slow Twitch has a great article on the topic.

Essentially, assuming you know your desired Pad X/Y, you then cross check that against the geo charts of any bike/size of interest. They should offer data that defines a “box” of adjustment option for max pad reach (X), and pad height (Y). Find the bikes that fit that range to your numbers.

In reality, some bikes will lead to people “fitting” into two size options. The difference comes from understanding where your size is within each of the sizes adjustment ranges. Some will me middle-ish, while others may be more towards a limit. Considering where you are now and where you might want to go in the future for possible changes can help select between a smaller or larger options.

Beyond that, simple considerations like wheelbase and related handling can come into play. All else equal, a longer bike will be more stable than a shorter one. So you may have a preference from that angle.


Related: I did a Google Sheet to look at sizing for one customer. I couldn’t get nice “blocks” to show, but this is essentially two sizes of the same bike (red & green rectangles), and two possible fits (remaining two points as pad x/y). He was considering a great deal on the Small, but it was not ideal for his needs, so I saved him tons of money from buying the wrong size bike.

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