Guru bike fit gone wrong?

The Nine Hammers Tavern - General Chat
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I’ve had a guru bike fit done from a reputable local bike shop. I’ve had to go back 4 times because something isn’t quite right. I suspected it was either the cleats, or a biomechanical issue (i.e. me/old injuries, lack of flexibility etc). Either way, after long endurance rides I had numb hands, the outside edge of my right leg was unbearably painful and my seat bones were sore, and don’t get me started on the perineum.

I started talking to a pro cyclist and sent videos of me riding - based on their advice I made a few changes and I can now do 4-4.5 hours with a sore rear end, but altogether it isn’t too bad compared to how it was. Main issue that seemed to help was my cleat adjustments, but I’m on my 4th set of bib shorts and my 3rd seat.

I’m almost fit enough to consider getting a new bike for gran fondos in the future - but the pandemic and lack of supply means I probably can’t ride one for the foreseeable future. So I started internet shopping trying to narrow it down a bit to pass time.

Here’s where it gets interesting. I use my guru bike fit data to compare against the specs. Now I know I won’t get a perfect fit bike, but I can’t even find a bike that is close to being in the right range. e.g. I need a medium/large 54/56 frame, but when I use my stack and reach from the guru fit data all the bike web sites would require me adding an additional 50-70mm to the stem to get close to the reach. Some websites reject my numbers and tell me they are incorrect, and others tell me they don’t make bikes that I can safely ride.

I do have short legs and a long body. But I didn’t think I was that freakish looking. :slight_smile:

I’ve tried contacting a few other places for bike fits, but none have responded because I don’t have a bike to be fitted to.

Is my bike fit bad? Any suggestions?

Martin

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What were you riding before the Guru bike fit?

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A cyclocross bike.

But I had the guru fit done for my wahoo kickr bike in an endurance position, knowing I would get an endurance bike soon. The wahoo kickr bike can be adjusted to almost anything.

Martin

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Check this out.
You can check your desired stack and reach numbers there, as well as compare bikes with what you already have.

Regarding bikes and granfondos, I would say get a gravel bike.
The have more stack for the same reach.

If you use road tires, it is just as fast.

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Were you doing 4.5hrs rides on the cyclocross bike?

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No, I wasnt doing long rides on cyclocross bike.

But I have done hundreds of 8+ hour rides in the past. And for the bike fit, I had them do a bike fit for an endurance bike amd then set the wahoo kickr up to match the bike fit.

Martin

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That geometry web site looks like it might be helpful for some research. Thank you.

I dont think I will get another bike fit done just yet, but will wait until bikes are more readily available and get it done then.

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Well, most bike fit recommendations that I’ve heard about are to make small adjustments because the body takes time to adapt to a new position.

I’ve always been more inclined to get the fit right first and then build up to longer durations in the new position. This still gives my body the time it needs, but it’s adapting to the optimal position and not some point, or multiple ones, in between.

That said, would you share your data, as others here would have the knowledge to determine if your fitter screwed up or if it’s just an issue with your body adapting to it.

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That’s the fit data from the guru fit. I’ve cut out the name of the company - it could well be me that is wrong here as I don’t know what I am doing.

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Height and inseam as well.

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181cm height, feet together.
72cm inseam. Taken with feet a few inches apart.

Martin

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One more question, what is the length of your crank arms?

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There are a number of methods to determine a “proper” saddle height. I find none of them get me completely comfortable with my position, thus my other topic on crank length.

With that caveat, the old standby is heel on pedal. That results in a saddle height that is a bit low, so I raise my saddle a few mm when using that method.

There is the Lemond method which is inseam in mm x 0.883. In your case this would result in a suggested saddle height of 635mm, measured from the bottom bracket to the top of your saddle. There are several downsides to this method though, among them that it doesn’t account for crank length or cleat stack height.

Another method measures from the pedal at bdc (farthest away and aligned with seatpost angle) to the top of the seat. This calculation uses 1.09 x inseam. In your case, it results in a saddle height of 748 (as measured). Assuming a crank length of 170mm that would put your saddle at 614mm from the center of your bottom bracket.

There are other saddle height formulas as well, so take these with a grain of salt.

Lastly, don’t be afraid to adjust your saddle height or fore-aft position. Just make sure to keep track of your existing position as a reference point that you can revert to.

EDIT: with 172.5 cranks, you’ll be at a saddle height of 612.5mm from your bottom bracket using the 1.09 factor.

That’s a discrepancy of 106mm compared to the values on your guru bit fit! Something’s not right there. I would expect to see values within a cm or 2, but 10cm seems way off.

Now, I’m no expert on this, and I’m hoping someone else will chime in here who is. That said, I have a 30” (76.2cm) inseam, and my saddle height from the center of my bottom bracket is 685, and that’s with 170mm crank arms.

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172.5

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See my edit above

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It doesnt look right does it!?!?

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If it were me, I’d start with heel on pedal and raise it from there until it feels comfortable.

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I called into a LBS that does bike fits. They looked at the numbers on the guru fit and said they looked very wrong. They threw me on one of the few bikes they had in stock (Specialized Aethos) 56 and 58 size and we settled on a 56 size. It’s not the bike for me, but at least I know it’s the guru fit that is wildly wrong.

I definitely can’t see myself getting a race bike. Great bike, just not the right bike for me.

Endurance or road/light gravel/forest trails/fire trails focused gravel bike I think it is.

Martin

1 Like
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Get a bike the right size then change the stem

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Yes - but the problem with my guru data is that when I get the right size bike, I need a stem that needs to be 7-9cm longer than the ones that come on the bike - in some cases, so big that manufacturers tell me that they don’t sell a bike to fit my dimensions safely.

The guru bike fit data is simply put, wrong.

Martin