Stack and reach
How high and how far forward the top of the head tube is, from the bottom bracket. They are the two numbers that decide whether a frame can be set up like yours.
BB, or bottom bracket
The axle your cranks turn on, in the middle of the frame. Every number on this site is measured from it, because it is the one point that sits in the same place on every bike.
Headset cover
The little cap on top of the head tube, under your spacers. Most makers do not publish it, so I assume 15 mm and add 6 mm to the band, which on its own is enough to hold an answer at "probably" rather than "fits".
Stem clamp, and its centre
The collar on the steerer that your stem bolts to. I need the middle of it. Where a maker gives only the height, I assume halfway up and say so on the answer.
Steerer
The tube coming up out of the fork. The cover, the spacers and the stem all sit on it, and it is the thing a mechanic cuts to length.
Bar reach
How far forward the hoods sit from the middle of the bar. Two bars on the same stem can put your hands 20 mm apart, which is why I ask.
Setback
How far your saddle sits behind the bottom bracket.
Drop
How much lower your bar is than your saddle.
Rails, and the rail centre
The two rods under your saddle, and the middle of the straight part of them. That midpoint is the point I use, because it is the one you can find with a tape.
The band
How far out I could be, in millimetres, and why. It is a straight sum of everything I had to assume rather than a clever average, so it errs wide on purpose.
wb, stand, trail
Wheelbase, standover and trail: how long the bike is, how high the top tube is where you straddle it, and how steady the steering feels. I show them against your bike, and I leave them out when the maker does not publish them.
est.
Estimated: a number I worked out rather than read off the maker's table. Anything marked this way can move if the maker publishes the real one.
Close Escape closes it. The measuring guide has the pictures. Open the measuring guide
Hongfu FM238
All-road · 5 sizes
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- Bike
- Hongfu FM238 · All-road · 5 sizes
- Geometry
- hongfu-bikes.com, fetched 29 Aug 2026, re-checked, no differences
- Cockpit
- Generic stem and bar, assumed
- Solved with
- cover 15 mm (assumed), max spacers 40 mm (assumed), stem clamp centre 20 mm (assumed), so every verdict carries ±10 mm at the bar
- Sheet
- 6 September 2026 · 210 bikes, 43 makes, 1,262 sizes in the catalogue
Geometry, every size, from the maker's table
The tinted row is the size drawn beside it. Press a size to draw it.The table runs on to the right: 6 more columns after Reach. Scroll it sideways to read them.
The M drawn to scale from the table, with no build on it. Stack and reach run from the bottom bracket to the top of the head tube; every size is solved from those two. One square is 100 mm.
The maker's cockpit
No stock cockpit I can name, so every size is solved on a generic stem and bar unless you choose one on the sheet.Generic stem and barAssumedNo bar is listed for this frame.
In the maker's words
Kept whole, as I read it off hongfu-bikes.com.SOLD AS A BARE FRAME by an OEM factory (Shenzhen Hongfu Sports Goods Co., Ltd; the page's only call to action is "I want to inquire"); no handlebar, stem or spacer kit is specified, so stock_stem_length and stock_bar_width are null and no stem angle, bar reach/drop, spacer stack or headset-cover height is published.
Cockpit and seatpost, in the maker's words · 191 words
SOLD AS A BARE FRAME by an OEM factory (Shenzhen Hongfu Sports Goods Co., Ltd; the page's only call to action is "I want to inquire"); no handlebar, stem or spacer kit is specified, so stock_stem_length and stock_bar_width are null and no stem angle, bar reach/drop, spacer stack or headset-cover height is published. integrated_cockpit is null because the cockpit is the buyer's choice: the spec block says "Compatible hidden cable routing" (the frame accepts a hidden-routing bar/stem) but names none. HEADSET: "FSA NO.55R 1-1/2 in, 1-1/2 in" (1.5 in upper and lower bearings; the HTML spec line spells it "FSA NO.55R1-1/2",1-1/2""). SEATPOST: round 27.2 mm (no post supplied or named; offset not stated; the "Previous" item on the page is the maker's separate "2024 New carbon seatpost utra light weight" listing, not tied to this frame). FORK: fork length (column E) 390 mm axle to crown and fork offset (column F) 45 mm on every size. OTHER SPEC (page and image): material T800/T1000 carbon fibre; tyre size 700C x 32C; disc size 160 mm; BB86 bottom bracket; "Universal derailleur hanger" (page: "Rear hanger: UDH"); sizes "XS, S, M, L, XL available".
SOURCE: hongfu-bikes.com is the maker's own site (HongFu Sports Equipment CO.,LTD / Shenzhen Hongfu Sports Goods Co., Ltd, Huiyang, Huizhou. Source: image_table (the maker's own product page carries the geometry only as a JPEG catalogue page embedded in the description
How I read the maker's table
OEM carbon frame factory). The product page http://www.hongfu-bikes.com/products/76.html (301 to https; the page also names itself http://www.hongfu-bikes.com/products/roadbike/76.html in og:url and http://www.hongfu-bikes.com/case/76.html in "Url for this article") is titled "2024 All road Carbon bike frame New design FM238", sits in the site's "Road bike" category, was published 2024-09-16 17:23:03 and has NO HTML table (zero <table> elements): the whole geometry is the embedded catalogue image named above; the other embedded image (https://www.hongfu-bikes.com/upload/image/20240916/1726478373384909.jpg, alt "FM238.JPG") is a photograph of the frameset with no data. MODEL YEAR: the geometry image itself is headed "2023 NEW All road frame" while the page title and the page's spec block say "2024"; recorded as 2023 from the chart that carries the numbers (the page is a 2024 re-listing of the same frame with the same chart). CATEGORY: the maker's own wording is "All road" ("ALL ROAD FM238" on the chart), recorded as all-road even though the site files it under Road bike. TABLE LEGEND (columns exactly as printed, mapped from the geometry diagram on the same image): SIZE = XS / S / M / L / XL; A = head tube length (drawn along the head tube); B = top tube, drawn HORIZONTAL from the extended seat tube axis to the head tube axis at the height of the head tube top, i.e. effective top tube; C = head tube angle (deg, printed with a degree sign); D = seat tube angle (deg, printed with a degree sign), drawn at the BB between the horizontal and the seat tube axis, 73.5 on every size; E = fork length, axle to crown along the steering axis (390 all sizes, no schema field, recorded in cockpit_options); F = fork offset (45 all sizes); G = seat tube length, BB centre to top of seat tube; H = BB drop (73 all sizes); STACK and REACH as drawn from the BB centre to the TOP OF THE HEAD TUBE (no headset cap); RC = rear centre = chainstay (415 all sizes); FC = front centre; WB = wheelbase. STACK DATUM: top of head tube; the collector's check bb_drop + (E + A) x sin(C) - F x cos(C) reproduces the printed STACK within 0.4 mm on every size (547.1 / 548.1 / 567.9 / 589.6 / 610.7 against 547 / 548 / 568 / 590 / 611), which also confirms the XS and S stacks really are only 1 mm apart (the S has a 0.5 deg slacker head angle). SEAT ANGLE CONVENTION: the column is labelled only "D" and the diagram draws it at the BB along the seat tube axis; the maker never says effective or actual, hence null. The seat tube is drawn straight and the 27.2 mm post sits on its axis, so actual and effective coincide in practice. NOT PUBLISHED (null): standover, trail, any handlebar or stem size. OTHER CHECKS by the collector (not stored as data): reach + stack / tan(D) reproduces the printed B within 1 mm on XS, M, L and XL and within 1.7 mm on S (531.3 vs 533, kept as published); the horizontal projections of RC and FC (using H as the drop) sum to the printed WB within 1 mm on every size; reach + (A + E) x cos(C) + F x sin(C) reproduces the printed FC within 1 mm, which explains why M and L share FC 588 and WB 992 (L's steeper head angle and longer head tube cancel out). No maker typos found. SIZING: the maker publishes no rider-height guide on this page.
Source: image_table (the maker's own product page carries the geometry only as a JPEG catalogue page embedded in the description, https://www.hongfu-bikes.com/upload/image/20240916/1726478457906923.jpg, 1937 x 1300 px, alt text "FM238_00.jpg", page number 8 of a Hongfu catalogue, holding a frame render, a spec block, a labelled geometry diagram and a 5 x 13 table; numbers read by eye from a 2x upscaled crop of the table; image NOT stored in the repo)