The Bike Fitting Mega-Thread


#61

Crank length might be useful to know (even if you are measuring from the centre of the BB spindle, seat height should be adjusted if the crank length changes).
Looking at the still picture at the start of the videos, you do seem very high - the knee bend is minimal and you are pointing your toes - I doubt you could level your foot out without completely straightening your knee.


#62

What kind of leg pain exactly?

  • Location, sharp/dull, time it takes to occur, etc.

Rear View - Saddle Height:

  • It does seem like your saddle may be too high. There could be some hip rocking, but it is hard to judge without being there. There is always some vertical motion visible at the shorts, but some if it is often the gluteus shifting, and not an actual hip rock. That said, it could be happening.

Side View - Saddle Height:

  • From your capture, I did an angle evaluation, and the 34-35* knee angle is about right. But notice the relatively steep toe point.
  • When you watch the video, you can see a late timed dip of the foot. This is common if the saddle is too high and the body runs out of flex, it drops the foot via ankle flex to get the length needed.
  • Toe point is fine if that is what you normally do, but this looks more like the “extra-dip” that is happening a bit late in the stroke and unnaturally to me. This and the potential hip rock do point to saddle possibly being too high.
  • I think dropping the saddle about 10mm and testing again is a good starting point. You can look for the same leg extension, but watch the ankle/toe point/hip movement to see how it changes, and especially how it feels.

Side View - Saddle Fore-Aft:

  • I got a screen grab from the side video. I can’t see the crank arm, but I dropped a line from the knee down. It seems to be close to or slightly behind the pedal spindle.
  • This could be OK, but (assuming a real plumb drop shows similar) you can also try moving the saddle forward around 10mm for a test, to see how it feels.
  • NOTE: if you do this, the move effectively shortens the saddle height, so you may want to raise it 3-5mm to compensate.
  • For a plum line, anything string-like with weight on the end can work. Even an old PC mouse or anything like that will get you close.

Lets get some info on your pain, digest that with my current analysis and regroup to see what you want to try. :smiley:


#63

I was actually, thank you for your feedback. Here all this time I thought my saddle needed to go higher :laughing:

@DuncanM23 - the crank length is 170mm. Thank you very much for your feedback :smile:


#64

One of the old rules of thumb about saddle height is that you should be able to sit on the saddle and put your heel on the pedal at the point where the crank is in line with the seatpost (also, then spin backwards and do it the other side without rocking your hips). Depending on your foot/leg length ratio, this then creates the desired knee angle.
170mm = 6.6 inches, + 29 inches to BB means your seat to pedal distance is >35 inches. With a 32.5 inch inseam, even allowing for the thickness of your cleat/pedal, I think that points to you being a bit high as well.
Your arms seem quite tense - are you using them to push yourself back in the saddle? That could also point to you being too high - sliding forwards reduces the effective seat height, so your legs might be trying to achieve that, with the rest of you working to keep them where they are. Don’t worry about the arms until you’ve got the saddle location right first though. :slight_smile:


#65

Thank you @mcneese.chad this is by far and away more feedback than I was expecting. A lot to digest and work through. I will post back here the results.

To answer your question about the pain though:

On the trainer after a 60-90 minute workout there is an odd sensation on the front bottom of my kneecaps. I would not classify it as pain though. It almost feels like a tendon has been repeatedly stretched that normally is not…

On my longer outdoor rides (120-480 minutes) that is where the real pain starts. Outsides of my knee, hips, and upper legs. I would not classify it as muscle soreness but a sharp hobbling pain. My thought has been that my cleat/pedals might be the main culprit. But now after the feedback I bet saddle height/position has a large play in the pain cause(s).


#66

My arms do feel quite tired during indoor workouts, not so much outdoors though (probably due to wind resistance and more varied stances on the bikes that I do not normally utilize on the trainer).
I am looking forward to putting all this advice into use. Thank you very much :smiley:


#67

Definitely record the starting position with the charts from the Park link I shared.

Then you can start making adjustments in steps. Ride a bit and evaluate the effect (good/bad/nothing) and report back if you have more questions.

Try to make only one change at a time, and then evaluate it’s impact. Doing more than one change at a time will not allow you to identify the direct cause of the difference and can lead to confusion.

Happy experimenting, and I am excited to see if we can help you :smiley:


#68

For those looking for tri fit parameters, here is what Jesse Kropelnicki of QT2 systems and coaching recommends. He talked to us at the USAT certification clinic and gave us a good demo on tri bike fitting. I fit myself using these and am going to the STAC virtual wind tunnel to make minor adjustments to make it more aero:


#69

Isn’t tri/TT fit exactly the same as road fit but rotated forward around the bottom bracket? I’d say that you need to find a powerful and sustainable fit for road, and then for TT/tri rotate forward until you no longer can see the road in front of you - done.
This is harder than it seems, and needs to be revised periodically. For that help, with feedback from my input, I’d be willing to pay. Angles however, I’m not paying for.


#70

As a pure concept, yes… that is the basic idea.

The challenge is that it is rarely that easy.

  • For one, I don’t know of a “calculator” that allows you to input your road setup and then output a TT/Tri setup.
  • Then you have the general issue that not all TT/Tri bikes allow for all fit combinations. Variations in adjustment range for Reach and Stack can lead to limits in actually applying the precise fit desired.
  • When you include the limits in the bodies that people have, you need to go into a fit with a basic goal (as above) but be open to working within the full set of criteria (limits) that make the bike/rider combo.

#71

Google Photos

I made two changes:
1 Dropped the saddle height by 2.5cm
2 Pushed the saddle forward by 0.5cm

My knees now appear to be more inline with my pedal spindle :smile:
Google Photos

I gave this a try and it still felt a smidge hyper extended at the bottom of the pedal stroke… Looking at this video as well I think my foot is still dipping too much:

Should I ride as is to test the adjustments I have already made? Or should I drop the saddle height another 5-10cm? If I drop the saddle height will this change knee/spindle alignment?


#72

Yup. That looks like a good starting point. 2.5 cm is a big change, plus the forward shift. Ride it and see how it feels.

The remaining toe dip looks way more natural to me. I think you owe this change some saddle time to see if you like it.


#73

That looks much better. I concur with Chad - try this and see if it is better before making any further adjustments.


#74

This is the approach I use, and then fine tune from there if needed. I also check and compare the BB-saddle distance on all my bikes as another check. Seems to work Pretty well.


#75

Has anyone come across an online calculator that will calculate contact point geometry of a bike? Ie vertical and horizontal distance between each of saddle center, BB (easier to calculate + measure than pedal spindle) and handlebars (I.e at the stem)?

Something like the following, but also capturing saddle height?

http://www.bikegeo.net

I’ve used a home-created spreadsheet to do this in the past to compare bike setups - comparing an existing bike to a new bike to inform new bike frame size and setup (spacers, stem), and found it to be very useful.

I can’t find the spreadsheet I created (:triumph:) and don’t really want to have to create one again from scratch. I’m looking at buying a new gravel bike, and want to compare vs the geometry of my current mountain bike and endurance road bike.


#76

That’s a pretty cool website. I’ve used https://geometrygeeks.bike/


#77

I’ve got a bike fitting booked for tomorrow and my fitter is a little worried that there’s not a lot of adjustment range available for my seatpost height. It’s a TT/Tri bike (a BMC TimeMachine '17) and the min/max insertion for the (bespoke, aero) post is not more than a few cm. To significantly lower the saddle requires a saw and significantly raising it requires, er, a new seatpost :rofl:

I’m happy to cut it and somewhat less happy to replace it; hopefully the cost isn’t eye watering - I think I’d have to ask an LBS to order one as BMC don’t seem to have them available to order. That’s by the by though.

Do you folks reckon it would be safe to have the post out of the minimum insertion depth a little during the fit, if it needs to go there, provided that I replace it with a correctly cut version before riding it properly (e.g. in a race or training)? Or is it a really silly idea?

I’m probably overthinking it as my fit doesn’t seem like it’s way off. It’s my own fault for buying a weird bike I suppose!


#78

Fine to do that in a fit only. Just ride lightly on the bike and mount smoothly. Gotta do what you gotta do.


#79

<Image removed - see reply below :smile:>

Bike fit part 1 of 2! My weird bike made it pretty slow going but we got a better saddle position. Need to raise the front end a bit to open my hip angle up a tad. More to folllow later.


#80

:open_mouth: There is nothing at all about that position that looks even remotely comfortable to me. In fact I think I have go take an ibuprofen just looking at it