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  #1  
Old 06-18-2022, 08:17 PM
PortlyPuncheur PortlyPuncheur is offline
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Not enough setback?

Hi all, enjoy learning from all of you, thanks for reading my first post.

I may be up against a saddle setback issue and hoping for some advice.

My regular road steed has a 73 degree seat tube angle, and I run the saddle pretty far back (not quite all the way) with a 25mm offset seatpost. I'm now setting up a new gravel frame with a 73.8 degree seat tube angle and realizing I may not have enough saddle rail to replicate the fit!

By my calculations, 0.8 degrees over 715mm (current saddle height) equals a 10mm difference in setback. I'm also running 160mm cranks, which perhaps exacerbates the issue.

I might be able to get it close enough, or just adapt over time, but curious if you have suggestions. Do some saddles have longer rails with more adjustment range? Current saddle is a Specialized Romin Evo 142 width.
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  #2  
Old 06-18-2022, 08:36 PM
Peter P. Peter P. is offline
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I'd say your problem is the short cranks.
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  #3  
Old 06-18-2022, 09:39 PM
PortlyPuncheur PortlyPuncheur is offline
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Quote:
Originally Posted by Peter P. View Post
I'd say your problem is the short cranks.
Unfortunately, they've got to stay. I've got hip impingement issues and going down to shorter cranks has saved my cycling life.
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  #4  
Old 06-19-2022, 02:27 AM
David Benson David Benson is offline
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A 30mm setback Vélo Orange seatpost would get you halfway there
https://velo-orange.com/collections/...t-long-setback
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  #5  
Old 06-19-2022, 09:45 AM
Peter P. Peter P. is offline
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Slide your cleats full forward on your shoe.

That's an option.

Because of that hip issue you have, and those short cranks, maybe it's time to get a custom frame so you can use more commonly available parts.
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  #6  
Old 06-20-2022, 05:45 AM
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rice rocket rice rocket is online now
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Exclamation

Excessive setback is also known to cause hip impingement, maybe your previous fitter created more issues by treating the wrong cause.
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  #7  
Old 06-22-2022, 11:39 PM
sheepdog84 sheepdog84 is offline
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it sounds like a different seatpost will get you roughly in the ballpark, if you want the rear end to be exactly the same as your Road bike.

Or even running a slightly longer cranks like 165’s?

Also quite interesting that your gravel frame had a steeper STA than your road frame - would you mind sharing the models of each?

When you sized down to 160mm cranks, what size were you on before?

Sorry - lots of variables here that more info would help!

Ok - personal anecdote time - i really enjoy discussing bike fit, so feel free to ignore the below, if you so choose.
_______________
As some one who has a road bike and gravel bike, and has considered this kind of situation, i’ll share my experience/advice:

Replicating exact fit measurements between bikes that have quite different variations in geometries, is usually a fruitless endeavor - especially when scrutinizing over millimeters.

For example, the front end of my road bike (STA 72.8) is probably a good 30-50mm lower than my gravel bike (STA 71.5) and my setback is less on my road bike, for that reason.

I know this distinctly about my bikes because the front end of my gravel bike basically has a “fixed” stem, where the spacer stack height was built into the base of the stem. No adjustment of the handlebars in relation to the saddle.

If these bikes had the same exact seat tube angles, the gravel bike would be near impossible for me to ride because the reach would be way way way too short. Likewise, if you lowered the front end of the gravel bike to match the road bike, but left the saddle in the same place, it’d be way too long and i’d basically be folding myself in half to try and ride it.

Point being, the gravel bike has my weight distributed more upright, and over the rear of the bike to provide traction to the rear wheel, in loose conditions.

Whereas my road bike shifts my weight a bit more on the front to provide more responsive handling in fast corners and decents (which the gravel bike definitely doesn’t have)

(This YT video further illustrates this point: https://youtu.be/Y3FTEgY5kAo )

So either my fit is wildly off and should be re-examined by a fitter that will tell me I’m objectively wrong, or I’m in the relative ball park of my fit because I ride both bikes with regularity and comfort



All this to say, 10mm isn’t too unreasonable of a window for getting a fit roughly correct. Hopefully this helps fill in the gaps or spurs the convo forward.
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  #8  
Old 06-23-2022, 12:07 PM
PortlyPuncheur PortlyPuncheur is offline
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Thanks for the post sheepdog, I also enjoy nerding out over bike fit...

Wow, your road vs. gravel positions are dramatically different then! I can see the rationale. Inadvertently, I'm ending up in almost the opposite situation.

About me:
175lbs 45yo male
Height: 69 in / 175 cm
Wingspan: 69.5 in / 176.5 cm
Inseam: 30.5 in / 77.5 cm
Sitbones: 115mm (? this is always a fuzzy measurement to me)
Slightly top heavy, usually wear medium bottoms and large tops.

Diagnosed with FAI (femoral-acetabular impingement) in 2021 and have improved since working with a PT and moving to the shorter cranks (170mm to 160mm). I don't think the FAI is cycling-caused, but may have been cycling exacerbated. Probably stems from a youth spent playing too much soccer, ultimate frisbee and various activities involving over-ambitious descents from height (snowboarding, kitesurfing, rock-climbing). I'm trying to delay total hip replacement, which is probably where I'm headed eventually.

My riding is typically not very racy, but what we (tongue-in-cheek) call "epic rides" that range from mostly paved to 50/50 mix of paved/gravel for 4-6 hour excursions. I've been riding to some extent for life (enthusiastic commuter) but only consistently doing 100mile weeks since 2019.

I started with a 2019 Cervelo C5 and still LOVE this bike. Endurance road geometry and can ride many of the above rides with 30-32mm tires.

The new gravel/CX bike is a Vitus Frameset was ordered from Chain Reaction and built up by me. Still early days. The goal was to pretty much duplicate the fit, since I will be riding both bikes pretty similarly, the choice dictate only by how chunky the gravel is going to get. I'm now realizing I looked too closely at reach/stack and didn't consider seat tube angle.

At present I've gotten pretty close, after switching to same saddle (Romin Evo, lower spec model with steel rails) and pushing it ALL the way back on the rails. I found online an FSA seat post that has 32mm setback. I may give that a go just to have the saddle in a more reassuring position on the rails.

I also realize that adapting to a further forward saddle position might have some benefits, such as opening my hip angle further or enabling me to bump back up to 165mm cranks. But whenever I try it seems I have excess pressure and numbness in the hands.

Sorry for the ramble! I'll try to attach some geo pics below.
Attached Images
File Type: jpg C5 Frame Pic.JPG (35.8 KB, 49 views)
File Type: jpg C5 Geometry.jpg (86.9 KB, 50 views)
File Type: jpg Vitus Frameset Pic.JPG (45.9 KB, 50 views)
File Type: jpg Vitus Geometry.JPG (66.3 KB, 50 views)
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  #9  
Old 06-23-2022, 01:50 PM
sheepdog84 sheepdog84 is offline
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Yeah, a focus on stack and reach really only tells part of the story of the geo, unfortunately.

Bikes can have the same exact stack and reach, but the fit can vary dramatically based on STA, how many spacers are applied, handlebar width, etc.. that's where the "you can always make a small frameset 'bigger', but cannot make a large frameset 'smaller'" saying comes in.

So, the Vitus stack and reach are shorter and lower than the Cervelo, comparatively. I'm not super familiar with Vitus, but this frameset is advertised as a CX Race bike, with race geo, and comparing it to your endurance geo Cervelo is going to result in an objectively different fit between the bikes (somewhat similar to what I was alluding to in my previous post)

That Vitus is most likely designed for short Cyclocross race efforts on tight, nimble courses (or maybe even gravel races). To your detriment, the sizing jump on that Vitus frame set is quite substantial, unlike Cervelo's sizing which is a bit more incremental.

So running seat post with more setback might be your only option to get that Vitus frameset to "fit" right. That model of Vitus might "fit" you then, but you'll want to take your intended use case into consideration as well. A CX Race geometry bike is not going to be nearly as comfortable on your long epic 4+ hour rides on gravel, as something more endurance oriented.

Have you checked out their "Substance", model? The ST on a size "M" frame is 73 degrees, and the front end stack height will be higher as well than the Energie Evo.

If not, There are literally tons of other options out there for gravel bikes with more endurance oriented geometries, rather than CX Race.

Let me know your thoughts.
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  #10  
Old 06-23-2022, 02:40 PM
PortlyPuncheur PortlyPuncheur is offline
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Do you have much experience with saddles that can achieve more reward position? I.e. long and forward-placed rails?

Totally agree, you make some good points about the different geometries, and perhaps this was a poor choice. I tend to be drawn to a racy feeling frames, despite not being much of a racer. The Cervelo feels pretty racy for an endurance frame, and the Vitus is (obviously) racy for gravel. With 15mm of spacers and a 20mm shorter stem it comes pretty close to nailing the fit of my Cervelo, apart from this setback issue.

The "gravel bike" it's replacing was a full on Ridley CX bike, so I was drawn by the potential overlap with cx. But let's be honest, a big part of what sucked me in was the price!

Who knows. As said it is still early days. Will put a few more miles on and see how I'm getting on with it, but maybe I'll end up frame shopping again.

In any case, it's probably time to have my "fitter" over for a few beers!
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  #11  
Old 06-23-2022, 04:10 PM
sheepdog84 sheepdog84 is offline
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You could check out some leather saddles such as Brooks or Selle Anatomica - they typically tend to have longer rails because they're effectively supporting a leather "hammock" seating mechanism, rather than just a rigid/static piece of plastic & carbon.

I run a Specialized S-Works Toupe 155mm on my road bike, and it's rails are a bit shorter than a Brooks C15 (IIRC), which I ran on my gravel bike. I recently switched to a Berthoud saddle, and those were surprisingly shorter than any other I had used previously - where the saddle is nearly fully aft.

YMMV!
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