Frame Sizing Confusion!

[Yogidave]

I can't be the only one here... I am shopping for a new road disc frame. I'm awesome with spreadsheets and looking for something more on the "endurance road" geometry.

To me, this means a relatively HIGH value to Stack/Reach. for instance, if you want an endurance fit with a reach of 395, and endurance ratio could be like 1.48. This gives a Stack of 585. (it's the MATHS!)

I'm 182cm tall with a 87cm inseam.

So, in many of the brands discussed here (Yoeleo, Miracle, Elves, OG-EVKIN, Carbonda, etc). buts me in either a "56" or a "59", neither of which is consistent across, or even WITHIN a brand. And, if you go by their sizing recommendations, I'd be riding a 53!

I've been riding and racing longer than most of these companies have existed.

So, how is everyone else picking their size on their CHINER frames?

Thanks,
Dave

[jannmayer]

I picked my road and gravel bikes by looking at the stack and reach numbers and comparing them to my old bike. I accounted for the shorter stem on my gravel bike and tried to match the handlebar location, not just the stack and reach. (Before I replaced my old bike, I played around with the stem length and height until I was happy with the fit, then I replicated that. )

The actual frame size numbers used to be comparable across brands, but when they went to sloping top tibes the seat tube length no longer made any sense. The size numbers and descriptions don't line up very well between brands so I don't pay attention to them.

Luckily, almost all brands, large and small, publish detailed geometry for the frames. Those numbers are measured consistently so it is easy to compare by geometry. Reach and steal work well for road bikes since the seat tube angle are fairly consistent. Mountain bikes are a bit more difficult.

[patliean1]

I've been riding and racing longer than most of these companies have existed.

Good lord.

And hello to you as well. Welcome to the forum.

1. Advertised frame "sizes" are mostly meaningless these days. Referencing the actual frame geometry of each size and comparing it to your current/previous frame geometry is more important.

2. Since you've raced longer than these brands existed, you will appreciate that people's frame size choice is based on numerous factors: Flexibility, riding style, body composition...you get the point.

3. It's possible that none of these CHINER brands offer a frame that fits your magical endurance ratio of 1.48. And that's perfectly okay. Folks these days are usually riding aero, climbing, or gravel bikes anyway. Even the big brands are struggling to reinvent their endurance frames.

[Velovelo]

I can't be the only one here... I am shopping for a new road disc frame. I'm awesome with spreadsheets and looking for something more on the "endurance road" geometry.

To me, this means a relatively HIGH value to Stack/Reach. for instance, if you want an endurance fit with a reach of 395, and endurance ratio could be like 1.48. This gives a Stack of 585. (it's the MATHS!)

I'm 182cm tall with a 87cm inseam.

So, in many of the brands discussed here (Yoeleo, Miracle, Elves, OG-EVKIN, Carbonda, etc). buts me in either a "56" or a "59", neither of which is consistent across, or even WITHIN a brand. And, if you go by their sizing recommendations, I'd be riding a 53!

I've been riding and racing longer than most of these companies have existed.

So, how is everyone else picking their size on their CHINER frames?

Thanks,
Dave

Interesting.

What is your current road bike frame and size?

Have you compared your current frame and the Chinese frames discussed in this forum using a tool like https://geometrygeeks.bike/

[Yogidave]

I currently ride a Masi CXRC size "57", which is technically a Cross/Gravel bike. However, Prior to that, I had a Willier Izoard XP size "XL/58".

I currently have a spreadsheet with some 60 possible frames worth of "data" and find that depending on the brand, I'm a "56" or a "59".  In a lot of cases, the stack/reach can be very similar across bikes. I wrote a few simple algorithms in XL to score the "fit" of these based on some specific criteria and then sorted by score and eliminated frames or sizes that, on paper, are clearly far away from a good fit for me.

For instance, within Yoeleo, I am considering the R11 in size "59" and the R12 in size "56". accept fo rht estack (and what would result in stem spacers to nearly match bar height), these are "equivalent".

I have absolutely used geometry geeks - it's an invaluable resource.

I'm just wondering if anyone has any wisdom to share about how they analyzed the mountain of geometry data as it relates to Chinese Carbon Fames.

It's almost time to spend money, so I'm doing all my diligence. 

[jannmayer]

I'm just wondering if anyone has any wisdom to share about how they analyzed the mountain of geometry data as it relates to Chinese Carbon Fames.

My approach was also to build a spreadsheet. I calculated the handlebar position for each frame, including the stem length and height, and played around with that to get my desired fit. Fit ultimately is where the handlebars are, and you can get the same fit on different frames with different stems and spacer.


This method let me know what frames would work for me with a reasonable stem and spacer combination. There were a number of frames that would have worked, so I was able to use other criteria to chose between them.

[Velovelo]

I currently have a spreadsheet with some 60 possible frames worth of "data" and find that depending on the brand, I'm a "56" or a "59".

Wow... "60 possible frames worth of "data"" ...this is cool. I wonder if this is available publicly for others to play around with?
How was this data collected?

For me I go with the stack, effective top tube length, seat angle and seat post setback (my expensive mistake was to leave out the seat post setback one time).
I compare these with my best fitting bike frame, spacers, stem + handlebar setup.
Come to think of it I don't really look at the reach values.



 

[Yogidave]

Methodology:
1. Over time.... looking at geometry charts on websites.
2. I started with straight up comparison of "stack/Reach" but that wasn't giving me the detail I felt I needed.... So... I built some equations that use trigonometry to precisely calculate stem and spacer impacts, saddle position, etc to fit. (bikes are all triangles, so this is basic middle/high school maths). Thank you Pythagoras! Make an functional equation once, and then copy it to 60 other rows to get the same metric for each frame. Basically, I calculated an "imaginary" stack and reach at the same STACK point in imaginary space and compared ALL frames to that (I did this to figure out which frames, stem lengths and stem spacers would match). This is EXTREMELY precise to the millimeter and compensates for differences in seat and headtube angles.
3. Defined algorithms to calculate a "fit" ranking (based on geometry vs current/past bikes I've owned) and a "value" ranking (based on cost, warranty, weight, etc). This is very personal. For instance, I de-prioritized weight over fit since i'm not racing and am, myself, 182cm and 86kg. I'm going to sweat out more than 100gr on a warm 60 minute ride.
4. Defined an "overall" ranking based on some math I tweaked several times to aggregate the FIT and VALUE ranking.
5. Sort, group and filter. Shockingly, the tool works very well to group into "top choices" , "maybes" and "no-go" groupings.
6. This is all pretty important since a lot of frames are now coming with one-piece integrated bar units that can't easily be swapped. You need to get it right BEFORE you spend $1000USD! For instance, My highest scoring frame, Tideace FM-R053-D that includes an integrated bar, needed a 100mm stem length x 44 CM bar width to fit, but the DO NOT offer that.. only 110mm x 44cm. The next size would have needed 60mm of spacers under the stem, so this one is OUT.
7. Communicate with Manufacturers ... turns out some frames the show on their sites are not available for various reasons. This further prunes the list.

And, lastly........

8. I'm a total dork and I realize this.

Sharing? it started in XL, but since I use a mishmash of PC and Mac, I moved it to Google sheets so I can access it from anywhere. It's sharable, so I guess I could..... I'm happy to if there's a safe way to do this.

[FHS]

Methodology:
1. Over time....
.
.
.
8. I'm a total dork and I realize this.

Um, yeah.

I don't mean this as a criticism in any way, but you've probably done more "due diligence" than 99% of the posters here who went out and built up a Chinese frame. I just don't think you're ever going to resolve your sizing issue to your satisfaction by just crunching data. It'll get you in the ballpark but, clearly, no one seller has exactly what you need. Even if you purchase all of the parts, relevant to sizing, piece by piece from multiple sellers to try to get exactly what you want, you're more than likely going to find that actual measurements don't have the accuracy you're looking for either.

This ain't archery, it's more like playing golf. Take your best swing, buy the frameset you think is going to get you closest to your fit, then make your adjustments. Luckily, you're not purchasing pieces that cost thousands of dollars, or even hundreds of dollars, for the most part.

If you think purchasing the frame is fun, wait til you start building it.

[jonathanf2]

This is the rare instance where I'm glad I'm short with a proportionate build. I don't have any of the issues that taller riders have when buying Chinese carbon framesets. In specific sizing cases like yours, I think you'd be better off buying in-person at an LBS.

[Velovelo]

First decide the kind of frame you are actually looking for.
The kind of frameset (i.e aero, endurance, all-rounder) will determine what reach and stack you'll have to compromise and settle for given the nature of the riding style of the frameset category.

I think you have done more than enough analysis to know what you are looking for.
Just compare all geometry parameters with your current bike geometry data and that is more than enough already to know what you can get. Don't over think or analyse it.
In my case for example, + or - 2cm I find is okay compromise on stack or reach, which can be compensated for with spacers and stem length respectively (with a zero setback seat post I must add).
For your case I compared your Masi CXGRc 2019* size 57 to the VeloBuild VB-R-099 size 56.
I find that you can definitely ride the VB-R-099 in size 56 with very slight adjustment with spacers and stem length + their zero setback seat post option. (This is just an example. I have stopped recommending any frame to anyone given the inconsistency of these dealers).

Since this is your first Chinese frame project you will need the ability and flexibility to change things both at the back and front of the bike overtime. Hence...;

- Go for a frame with a none proprietary seat post so you have options with seat post setback. Or get a frame with proprietary seat post but with a zero setback so you only deal with saddle fore aft position.
- Use a flexible headset system like the FSA NO.69 SRS so you can further adjust stack & reach using the regular cheaper spacers, stem and handlebars to your satisfaction before locking it down with a fixed cockpit system.
- Be ready to get your hands dirty because even after your analysis and due diligence, the seller may send you stuff that is way below your expectations. Then you will have to get creative to make the best out of the situation.




All the best with your project.



 

[Takiyaki]

I just look at geometry data. Sizes aren't even consistent in one brand. I have a Dengfu FM208 in size 54. I'm looking at an R06. Geometry indicates I should get a size 56 to keep similar stack/reach. It is what it is.

[Yogidave]

Done!

Pulled the trigger and ordered a Yoeleo R11 size 59. They have zero offset posts available and will provide an assortment of spacers. Their integrated bar/stem sizing works. Semicustom painting without an upcharge!

Great communication and they offered me a 15% off coupon!