The Bike Fitting Mega-Thread


#1

This is a primary thread to discuss Bike Fitting methods and issues.

  • I will edit this lead post with useful links for starters.
  • Feel free to post your questions and issues, and we will do our best to address them.

A bit about me:

  • My bike fit interest started back in 1997 with the Fit Kit Systems which was based in my home town at the time. I started learning about saddle setup, cleat alignment, and front end settings. I used that info to experiment with my fit and those of a few friends.
  • I am now a part-time fitter at my local bike shop. I have completed the Specialized Body Geometry Fit programs, Level 1, Level 2, and Level 3 (2014-2016).
  • I have performed around 100 fits and assisted others in around 50.
  • My personal fit philosophy is that every fit is unique.
    • The most important tools of a fitter are the Ears (listen, hear and understand what the rider says) and the Eyes (watch for every detail possible and look at the situation in total).
    • There are no rules that fit all situations or riders.
    • Every “rule” is meant to be broken, but the key is knowing when to do that.

Disclaimer: All advice provided and discussed here should be reviewed before implementation. Fitting is complex and it is not always possible to cover all the possible variables that may influence overall results.


Reference Links:

Bike Fit Measurements and Charts:

Saddle Height:

Misc:


Full length of saddle adjustment - any concerns
TT/Pursuit position critique
Let's see your paincave!
More Power in the Drops
#2

Great thread… Since I was thinking about this the other day. Back when I started riding, the conventional wisdom for MTB riding is that it was perfectly normal to have your seat lower than you would on your road bike. Now that we are in an era of dropper posts being the norm… should we be bucking this and setting the seat height as best to produce power? I’m thinking that you can always fine-tune it down, but you can not get it higher unless you initially set it up that way.


#3

Maybe…
(I need to refine this. I’m rushing to get something added, and will improve the detail in a bit.)

It depends on a several factors.

  1. Pedal Type: Flats vs Clipless

    • Flats often lead to a different foot position through the pedal stroke. It can be more level (vs toe pointing on clipless). This is done to ensure proper engagement with the pedals, but also to help in dropping the center of mass a bit (which benefits handling). As such, you may end up with a lower effective saddle height with Flats.
    • Clipless leans a bit more towards a road bike style fit, but should be considered in the context of the off-road situation.
  2. Pedal & Shoe Stack Height:

    • Pedal stack height is from the center of the spindle, to the contact platform.
    • Shoe stack height is from the bottom of the shoe to the top of the foot bed.
    • Overall stack height is the combination of the specific shoe and pedal. Each shoe and pedal combination will have a different stack height. It ends up being is the space between the bottom of the foot (in the shoes) and the center of the pedal spindle (on the cranks).
    • So it’s important to keep this in mind and not blindly apply a known saddle height from one bike to another.
  3. Crank Length:

    • MTB bikes are leaning towards shorter cranks for ground clearance. Regardless of this trend, it’s common for a MTB to have a different crank length compared to a similarly sized road bike. So be sure to factor crank length variation into your adjustments
  4. Event/Ride Type: XC, Enduro, Trail, etc.

    • I can expand a bit, but the specific discipline may lead a rider to pick a higher or lower max height, even with the presence of a dropper.

#4

What’s your take on saddle tilt?

With a hammock style saddle - curved profile - I install it absolutely level from back to front, shove it all the way forward on an inline seatpost and then lower bit by bit until my perineum is comfortable, back of knees don’t get stretched and calves don’t hurt.

Am I doing it wrong?


#5

Very detailed explanation, thanks! I usually don’t have a set height when doing saddle height on different bikes, but use the similar height as a starting point. I mostly just take my hex keys with me, and start riding around a bit… fiddle, ride a bit more, fiddle until I find what feels natural to me.

Although after reading Rappstar’s article about seat height, sounds like I shouldn’t be too concerned about making the height higher. The consequences of a seat too high are worse than the seat being a little too low.


#6

I’d love to get recommendations of bike fitters, too. By city/region. I’m in New York City, BTW.

:smiley:


#7

You experimentation is great. It’s a great way to arrive at the best solution for you. It just takes some time and being mindful, to get the best feel and prevent injury.

I know my comment was overly broad, partly because there are many considerations. But with the advent of droppers, I think we can reasonably run higher settings that we might have in the past with rigid posts. Do as you have and play around until you find what works.


#8

Each setting you mention should be considered independently, but in context of the overall fit. I will break them down.

  1. Saddle Angle:

    • Generally, start with saddles level. This can change with curved saddles as many need to be a bit higher at the tail than the nose.
    • You need to consider the shape and intended use. Try it and see if you are fighting with sliding or excessive pressure.
    • Try to limit non-level to no more than 5* up or down in most cases.
  2. Saddle Fore-Aft Position:

    • There are conflicting thoughts on this and some strong opinions. The easy and old stand by is Knee Over Pedal Spindle (KOPS).
    • KOPS = Saddle at proper height, cranks level, and a plumb line dropped from the forward part of the knee to be flush with the end of the crank arm. Older methods were dropping the plumb line just the knee cap and bisecting the center of the spindle. The new flush knee/crank end is a simple approach with the same goal.
    • Note: This setup above generally applied to road and some MTB cases. TT and Tri tend to have the knee forward of the crank around 4cm with notable adjustments to suit particular fit needs
    • KOPS is loved and hated. In either case, it should be considered a reasonable starting point and not necessarily the be all, end all solution.
    • I won’t cover the other methods right now, as they are more work to explain, but are worth consideration as well.

I won’t say you are doing anything wrong. There is not enough info to know right now.

But I will point out that your fore-aft method will be influenced by any bike you ride as the seat tube angle (and any differences from bike to bike) will directly affect your results. Particularly, if you slam the saddle forward, that will tend to lead to a position more forward and possibly in front of the Bottom Bracket.

That may be functional, but you will see different positioning on a bike with a 70* seat tube vs one with a 73* seat tube. That’s just a simple example, but depending on saddle height, that 3* may lead to a fore-aft change of a few centimeters.

So, it’s possibly problematic depending on each case.

For height, looking for excessive strain behind the knee is a good observation. That is a common sign of a problem. It may also present in calves and Achilles tendons, hip or saddle discomfort from rocking and other issues.

Sadly, there are few easy answers in fitting. But one thing that is becoming a bit of a mantra, is to make sure saddles are not too high. Seems we have tended to go that direction in search of power, and my be going too far. So some testing and evaluation is likely in order. I am experimenting on my own setup as we speak.


#9

Thanks!

I slam my seat forward because I want to get low in the front without pinching my hip angle and lose power. It also feels easier to stomp down on the pedals when at 350-400 W than to push on them in front of me. If my seat would be angled down as well, I’d have way too much pressure on my hands.

I sit something like this, but since I’m not constrained by UCI rules of saddle placement, I shove my saddle forward so that I don’t have to sit on the nose. And yes, I understand that this works better for shorter, intensive rides, and/or for people who are light and have a high ftp. Otherwise, there’s too much hand pressure.


#10

Yup, you have made a great choice and considered the context of your needs. The forward saddle position is very helpful for the long and low approach you want. It’s best for the very reason you mention.

Great application of known changes to reach your desired fit :smiley:


#11

I am looking forward to any information I can gain on this topic. I have never had a proper bike fit, I just researched what I could online and through trial and error, translated that information to my own bike.

I would like to learn how to properly fit each type of bike. BMX, MTB, Road etc. Especially for my kid’s sake. I was 27 years old by the time I had ever considered that bike size and set up was important and I had been riding BMX and MTB for most of my life.


#12

Cool. I am happy to offer my opinion and want to try and pull from many other sources, so we can have a broad range of looks at the topic.


#13

From the ISM thread - am I wrong?


#14

I need more time for a fuller reply (headed to bed). And in general I try to avoid the right/wrong type of discussion when it comes to fitting, as there are few absolutes.

You touch on several topics and make some strong statements (i.e. ISM comment). I either don’t have direct experience with some of the topics or I look at it via a different perspective.


#15

thanks @mcneese.chad to encourage me to post my planed fitting again here.

I own a Panasonic PR 2000 of size 53cm and I am 177cm tall with an inseam of about 85cm. And I bought the ISM PN 3.0. The goal was to get me in a reasonable aeroposition to train on trainerroad. I am new to cycling/triathlon and do not want to invest in a professional bikefit because maybe I do not stick with it

So I was following this youtube video and double checked if I am in the suggested angle range here

I installed a fast forward seat post to find out that it is not possible to follow the instructions. So I am looking forward to buy a regular seat post :smiley:


#16

I’m intending to go for a bike fitting for the bike I currently have on my trainer (which is also my outdoor summer bike). One problem I’ve had is persistently getting minor but annoying perineal abrasion and occasional sores.

But what I’ve noticed is that I almost always get them on the left side only. Does this suggest that there’s an imbalance present, which if fixed could make me more stable and comfortable? I’m thinking cleat shims or footbeds - something that might correct a minor difference in leg length.


#17

Leg length discrepancy? Injury on one side making that knee extend less? Other mobility imbalances? Saddle too high, which exacerbates everything?


#18

I’ve had a similar issue and I can feel Im putting more saddle pressure on my right side and my saddle seems to be straight. I also have a small amount of pain on my left knee but nothing that stops me from getting through a workout. Ive had ACL reconstruction with a hamstring graft on that left knee and noticed my left knee doesn’t have the same extension as my right knee, should I be setting my saddle height to my left knee (leg)? Should I also be extra careful about my saddle for/aft position in regards to my left knee? I am currently still working on my position on my new bike and have the saddle pushed pretty far forwards. Thanks in advance!


#19

@mcneese.chad

I am considering buying a gravel bike in the next couple of months, and as a fitter, I’d be interested in your opinion as to whether I should get a fit before buying a new bike and trying to match stack and reach, or get a fit done with my new bike.

By way of context:

  • I have never had a bike fit, but have got comfortable on my entry level road bike through trial and error.
  • I think I am one of those people that adapts fairly easily to any reasonable position.
  • I have shorter legs and a longer torso than the standard frame sizing models suggest.
  • I have no pre-existing injuries.
  • I don’t race - my target events are metric doubles (and longer) and challenging sportives.

#20

Yes, always adapt to your worse leg/side. If that causes injuries on the other sides, you’re so imbalanced (leg length discrepancy?) that you won’t be helped on a forum - you need a physiotherapist/good bike fitter.

Regarding fore/aft and knee health, I’ve never understood the reasoning. If your hip angle remains the same and you’re rotating around the bottom bracket, fore/aft doesn’t matter for your knees. If you alter the hip angle or change your effective saddle height, it matters.