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  #16  
Old 03-03-2023, 09:24 AM
Road Fan Road Fan is offline
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Originally Posted by PortlyPuncheur View Post
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.
First, stack and reach are characteristics of a bike frame, not of a bicycle. Neither of those dimenions says any thing about saddle setback. I think they were invented by a time trials bike specialist, where saddles are slammed forward, if anything, not conceived for "standard roadies." I do think stack is a good target.

I'm 5'6", 81.5 cm pbh, and I like 53 cm c-c as a seat tube size. I also like setback, and have been happiest with saddle setback equivalent to about 71 degrees STA. Your Cervelo "pick" looks too big, given your pbh of 77-something cm. But finding a 53 cm frame with a shallow seat tube will be a long search.

I would say get a good builder/fitter to make you a custom frame, or find a frame builder to teach you how to do it yourself. Doug Fattic here in Michigan comes to mind.

If you don't want to go that way you can make yourself a test bik just by going to a deep-setback post like a Nitto S-84, AND a saddle with very long rails like a Selle AnAtomica X with their steel rails, or maybe a Specialized Toupe, which also has very long rails.

I would keep the aspects of your fit that you think are appropriate, like the foot position, and from there try refinements, like butt position and then bar reach and height.

From what you learn you can spec out a custom frame.
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  #17  
Old 03-03-2023, 02:31 PM
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fourflys fourflys is offline
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Quote:
Originally Posted by Road Fan View Post
I'm 5'6", 81.5 cm pbh, and I like 53 cm c-c as a seat tube size. I also like setback, and have been happiest with saddle setback equivalent to about 71 degrees STA. Your Cervelo "pick" looks too big, given your pbh of 77-something cm. But finding a 53 cm frame with a shallow seat tube will be a long search.
I could be wrong here, but a 81.5cm pbh on someone that's 5'6" is long legs.. so it makes sense you would like a lot of setback (longer femers and all).. my pbh is more inline with the OP (and at 5'9", I have short lets for my height)..

I find it curious you think the Cervelo is too big.. the standover height is 755mm, which sounds like, while it may be a bit tight, should allow enough standover for a road bike, no?

I guess my question is what do you find too big? genuinely curious as that's the size I would pick as well (being of similar proportions to the OP)..
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  #18  
Old 03-03-2023, 05:15 PM
Road Fan Road Fan is offline
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Originally Posted by fourflys View Post
I could be wrong here, but a 81.5cm pbh on someone that's 5'6" is long legs.. so it makes sense you would like a lot of setback (longer femers and all).. my pbh is more inline with the OP (and at 5'9", I have short lets for my height)..

I find it curious you think the Cervelo is too big.. the standover height is 755mm, which sounds like, while it may be a bit tight, should allow enough standover for a road bike, no?

I guess my question is what do you find too big? genuinely curious as that's the size I would pick as well (being of similar proportions to the OP)..
The seat tube length struck me as pretty tall, considering how its working out for me. I'm going through working out the Lemond Method "Complete book of Bicycling" by Kurt Gordis and Greg LeMond. That process, and nearly all the others I've looked at and used over the years, do not consider standover height. I'm recommended to have a 53 cm c-c frame. The standover in that case can be calculated from seat tube combined with TT diameter, seat tube angle, and the BB height. The bike in question has adequate SOH for me, but I don't have all those specs written to be able to use them now.

When you consider what SOH is all about, you do not want it tight. But if I have a frame with good STL, I haven't had standover problems. I have one bike which is too tall in the crotch, and it is also a 56 cm. I don't ride it much, despite the great tubing.

But as much as I play with the numbers, I'm not a pro or expert.
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  #19  
Old 03-03-2023, 11:10 PM
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fourflys fourflys is offline
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guess what I was saying is I didn't see a ST measurement in the Cervelo specs.. I don't usually size a bike by SOH, but that was the only number they gave for that parameter that I saw..
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