Trademarks other than those owned by BSn used throughout this manual belong to the owners and are used here in a purely editorial fashion.
Road Bicycle (6.6 cm hanger drop, 270 mm. "bottom bracket height") | |
Model | Frame Height (c-c) |
---|---|
Cycling Science | 55.3-56.2 cm |
Merlin | 57.1 (c-t) 55.6 (c-c) |
"Abfahren/VSF" variant (Table) | 82.0-82.3 cm (standover) 56-60 cm. (c-t) [typ. ~56 cm. (56.0) c-c, ETRO 622 tires] |
Height based | (min)55.1 - 59.0(max) (56.2 average) cm. |
Gary Klein's (Height based table) | 59 cm. (c-t), ~57 (c-c) |
A simple rule is thumb: The frame height (c-c) is the length J. Attributed in Hinault's book to Merckx's mechanic, this model is both easy to measure and seems to produce reasonable values for frame height: although the frame height is generally given as proportional to the measure of inseam (E) or, the more difficult to (correctly) measure "trochantric height", outseam (O), a longer, resp. shorter femur relative to tibia, viz. the ratio "C/J", implies that the seat should be more pushed back, resp. raised, from the normative base position. While the femur length also contributes to saddle height, in series frame production, the larger the frame, the more laid back the seat tube and the more one can push the saddle back behind the bottom bracket. The longer the femur w.r.t. the length of the tibia, the flatter the seat-tube angle that is appropriate. Also the longer the cranks (dependent upon femur length), the less the required saddle height (above the bottom bracket) whence the smaller the requirements on frame height.
Summary: To increase rigidity, reduce weight and afford a lower Cw the trend is to select the smallest possible frame that affords a proper seat position, reach (top-tube length and handlebar-seat rise) and response (stem-length). A slightly smaller frame, in general, can be compensated by other parameters such as stem and seat post length variations but a larger frame (less stability, more weight, poorer aerodynamics of the rider/bicycle unit), in particular a too long top-tube (less control) leaves much to be desired. The main constraint on seat-post height selection (as alias for frame-height) is the length of the stem quill. The use of a positive stem instead of a "7"-stem, as was common practice for mountain bikes, can afford more height-- a technique followed by some of the road products of Klein and Giant-- at the cost of traditional aesthetics. Cyclist with morphologies substantially variant from the norm (some women and a very small percentage of men) will need to seek the advise of an experienced custom framebuilder. |
Frame Builder | Height (c-c) | Top-Tube length (c-c) | Seat Tube Angle |
---|---|---|---|
Cinelli | 550 mm | 550 mm | 73.0 ° |
Cinelli | 560 mm | 560 mm | 73.0 ° |
Colnago | 555 mm | 553 mm | 73.0 ° |
Colnago | 565 mm | 561 mm | 73.0 ° |
DeKerf | 555 mm | 570 mm | 74.0 ° |
DeKerf | 575 mm | 585 mm | 74.0 ° |
DeRosa | 550 mm | 550 mm | 73.5 ° |
DeRosa | 560 mm | 560 mm | 73.0 ° |
Fondriest | 550 mm | 560 mm | 73.0 ° |
Fondriest | 560 mm | 565 mm | 72.5 ° |
Habanero Ti | 545 mm | 560 mm | 73.5 ° |
Habanero Ti | 565 mm | 570 mm | 73.5 ° |
Independant Fabrications | 550 mm | 560 mm | 73.0 ° |
Independant Fabrications | 560 mm | 570 mm | 72.5 ° |
LeMond | 550 mm | 565 mm | 73.0 ° |
LeMond | 570 mm | 575 mm | 72.5 ° |
Litespeed Classic | 555 mm | 565 mm | 73.0 ° |
Litespeed Classic | 575 mm | 575 mm | 73.0 ° |
Litespeed Ultimate | 555 mm | 565 mm | 73.0 ° |
Litespeed Ultimate | 565 mm | 570 mm | 73.0 ° |
Merckx | 550 mm | 555 mm | 73.0 ° |
Merckx | 560 mm | 560 mm | 72.9 ° |
Merlin | 555 mm | 565 mm | 73.0 ° |
Merlin | 565 mm | 571 mm | 73.0 ° |
Marinoni | 550 mm | 555 mm | 74.0 ° |
Marinoni | 560 mm | 560 mm | 74.0 ° |
Richey | 540 mm | 540 mm | 73.5 ° |
Richey | 560 mm | 560 mm | 73.5 ° |
Serotta | 550 mm | 555 mm | 73.0 ° |
Serotta | 560 mm | 560 mm | 73.0 ° |
Torelli | 540 mm | 545 mm | 74.5 ° |
Torelli | 560 mm | 560 mm | 74.0 ° |
The above builders [ed: submit complete data for inclusion in this list to edz@bsn.com] and the frame sizes shown are for the basis of comparison. The builders were selected as representative of popular frame kits that each illustrate a different philosophy and perception of their average "customer". (Overly) Simplified:
One should select, in general, on the basis of power, stability, ergonomics (comfort) and use. |
Crank Length | |||
Typically cranks are 170, 172.5, 175.0, 177.5 or 180 mm in length. The "standard" crank length is 170 mm for road and 175 mm for mountain bikes. Despite vast differences in femur and inseam/outseam length among professional cyclists, most professional cyclists traditionally select cranks in the range of 170 to 175 mm--- and at most between 2.5 and 5.0mm longer in mountain and time-trial stages. | |||
Model | Length (G) | G/C | Circ/E |
---|---|---|---|
C-proportional | 177.50 (177.3) mm. | 28.4 (1.3) % | 1.288 |
LE (1.0250×E+86) | 174.6 mm | 28.0% | 1.269 |
LE (1.4300×C+86) | 175.2 mm | 28.1% | 1.273 |
Kirby Palm (2.16×E) | 186.8 mm | 29.9% | 1.357 |
Palm derivate (2.99×C) | 186.8 mm | 29.9% | 1.357 |
Ed(mund) Burke (Height based table) | 172.5 mm | 27.6% | 1.253 |
Burke derived (inseam based) | 172.5 mm | 27.6% | 1.253 |
Roger Marquis (Height based table) | 172.5 mm | 27.6% | 1.253 |
MarquisE derivate (inseam based) | 172.5 mm | 27.6% | 1.253 |
MarquisC derivate (C based) | 172.5 mm | 27.6% | 1.253 |
U.S. OTC (~K/2 + 82.5) | 175.0 (174.5) mm | 28.0% | 1.271 |
OTCE variant (1.06*E + 82.5) | 175.0 (174.2) mm | 27.9% | 1.265 |
OTCC variant (1.47*C + 82.5) | 175.0 (174.2) mm | 27.9% | 1.266 |
Hinault (Conventional) | 175.00 mm | 28.0% | 1.271 |
ConventionalC | 175.00 mm | 28.0% | 1.271 |
Hinault's 2nd table (Competition) | 177.50 mm | 28.4% | 1.290 |
CompetitionC | 177.50 mm | 28.4% | 1.290 |
The selection of crank length is theme that more resembles religion than bio-mechanics. While it is commonly accepted that too long cranks can create undue stress on the knee the issue of optimum length is little, if not at all, understood. Although the "170mm cranks fits-all" viewpoint, dominant though the 50s and into the 60s, is no longer widely accepted, what little empirical research has been conducted has delivered inconclusive and often contradictory results: Some leading to very short (130 mm) and others to very long cranks.
|
Seat Height (Hs) | |||
The maximal seat height is proportional E, resp. O, and J. It is measured to the surface where the "sit bones" rest. | |||
Model | Height | Comments | |
---|---|---|---|
Amsterdam/Gregor/Rugg (1.090×E) [Pedal to Seat Model] | 94.3 cm. | pedal to seat | |
76.5 cm. | mid bottom-bracket to seat | ||
New Amsterdam (104-106% of E) | 89.9-91.7 | pedal to seat | |
French (0.883×E) | 93.6 cm. | pedal to seat | |
76.4 cm. | mid bottom-bracket to seat | ||
French Variant | 76.1 cm | mid bottom-bracket to seat | |
Hügi (0.885×E) | 93.8 cm. | pedal to seat | |
Hu=76.6 cm. | mid bottom-bracket to seat | ||
Mark Minting (1.0568×E) | 91.4 cm | Pedal to seat | |
Typical Mass (175.0 mm cranks, 12 mm shoe sole and 15 mm pedal height) | |||
The models based on factors to determine the pedal to seat, except explicitly the Minting model, have been found to assume a specific length of crank.
There are many other models. Some are based upon sprinting backwards with ones heals (and then raising the seat between 5 and 15 mm.), and others upon static joint angles (so-called Goniometer Method). In later method, popular in Triathlon, one is seated on the saddle, foot in the pedal at 6 o'clock position and the saddle is raised/lowered to form an angle of around 30o in the knees. Both these paradigms seems to be based on Voodoo but produce reasonable starting measures that are, perhaps, no worse than the anthropometric measures above. All these methods tend to produce a range of values within a few cm. of one another. Foot size, technique and other factors also contribute to differences in personal saddle height. Higher, resp. lower, seat positions tend also to contribute a tendency to pedal toe-down (Pedaling with the balls, e.g. Hinault), resp. heel-down (e.g. Merckx), and in some cases "to ankle": dropping ones heels at the top of the stroke [ed: one should lower the seat and try to adopt a flatter more heeled foot position]. On the other hand, the seat height depends also upon the (preferred) pedaling style and horizontal position. A style with lowered heels will also require a lower seat height. Start with the lowest acceptable height and slowly raise the saddle, over a longer period, in increments of 5 mm. to try to find the optimal height. Note: Its better to be 1 cm sub-optimal than to set the seat-post too high. While the former can at most marginally reduce performance, the latter can be unhealthful. |
Saddle Tilt | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Most saddles should be installed to have the seating surface level. Traditional tensioned (kern) leather saddles such as the Brooks, by contrast, should be positioned (by design) so that rear portion is very slightly higher than the neck and nose. Tilting the nose of the saddle down places more weight on the "sit bones " while raising the nose shifts more weight to the perineal region. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Measure | Value | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Seat Position | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Seat-tip behind bottom bracket | (R) = 7-9 (7.1 - 8.1) cm. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Seat-tip to handlebars | (S) = 56 - 60 [57.1] (56.4 - 57.4) cm.(typ.) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Saddle projection | 6.2 cm. [p=13.3 cm, f=7.1 cm, t56.4= 634.8 mm] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The view is that the saddle should be positioned "up and back". The longer the tibia and foot (measured to ball), the higher the saddle and the longer the femur, the more it should be "pushed back". First position the height and then the horizontal position. One should use a plumb line dropped from the tip of the saddle to measure the position, as specified above, behind the bottom bracket. As a simple check, with average morphology, one can drop a plumb line from the knee-cap and it should be on or behind the pedal axis. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stem Requirements (length/quill) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stem-seat proj. | (S-L) = <53 mm. [560 mm. top-tube 72.9o frame] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stem length (l) | 116 - 140 mm (top-tube model) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
100 - 130 mm. (seat height Model) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
120 mm. (Neutral) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Handlebar under Seat | (D) = 8-9cm (10.9 height). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Dmax = 10.5 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Aerobar-pads under Seat | (Daero) = 12.5 ±1.5 cm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The above fit guidelines have assumed the average upper-body mass of European elite cyclists. Many cyclists (esp. Americans) tend to have (not to mention those that lift weights) more weight in their upper-body and should tend towards slightly longer top-tubes and shorter stems than those recommended here.
Alongside the above models there are several other popular methods for the determination of stem length from the basis of a correctly adjusted saddle position:
The stem length and height are not just related to the build of the rider and geometry of the bicycle but to condition, training and other individual factors. They also depend upon the form, reach and drop of the handlebar. Nitto #185, Cinelli #64 and #66 have, for instance, drops of, resp., 140mm, 145mm and 156mm and reaches of, resp., 87mm, 80mm and 87 mm. The requirements on stem length for a given position "on the hoods" or "in the drops" between a Cinelli #64, #66, Nitto #185, Modolo Q-Even, ITM Italia Pro or a 3TTT Merckx can vary by as much as ½ to 1 cm! [ed: So much for the folklore of "eyeballing the hub" even with average morphology]. Deep drops (e.g. the Cinelli #66) are, in general, for larger cyclists and, in particular, those with relatively longer upper-arms and/or shorter torsos. [ed: Some models specify the drop, by contrast, on the basis of the handwidth: that the hand should be at least as wide as the H(see below)-60, e.g. >9 cm. for deep and < 7-9 cm for medium.].
If ones arms hurt on longer rides it can well be that the stem is too long. If the neck and shoulders or wrists hurt, then the culprit could be a too short a stem [ed: Or a saddle tilted nose-down placing too much weight on ones hands]. In general, the stem should be no lower than the above (Handlebar under Seat) value. A lower stem will do little to improve aerodynamics. Holding the handlebar in the drops with elbows bent at 110° ones back should be nearly flat. If ones legs make chest contact then the stem is way too low. Traditional (hot) forged Italian stems (e.g. Cinelli) have cone expansion and 135mm quills. The, increasingly popular, TIG-welded stems (CrMo and Ti) tend to use wedges and have 125mm (or shorter) quills. The maximum height is determined by where the head-set threads are located. This is determined by the bicycle fork and not the markings on the stem. The MAX HEIGHT markings are a guide and are primarily provided for product liability and CSPC requirements. The expansion or top-of-wedge, to prevent severe damage, must be below the threads. Up untill a few years ago the wedge was a hallmark of low cost, sub-standard, stems since they are easier to make and are production tolerant. Over the last few years the wedge has advanced in status and is used even in the expensive Ti and nearly all CrMo stems. The problem with cone stems is that they require, in comparison to wedge designs, more attention to assembly. The cone expansion not only requires more torque (to keep the stem from twisting), but over-tightening can bulge the steer tube. The wedge design, although less prone to incorrect assembly and easier to adjust (cones often need a little wack with a rubber hammer), can present to the steer tube added stress at the top of the wedge, a full 30mm from the bottom of the quill--- whence offer less height and an additional potential source of steer tube damage. Since the trend in the bicycle industry is towards reducing assembly costs (witness the rapid acceptance of Ahead-Set® and cartridge throw-away bottom brackets) the expansion cone design is destined to join the ranks of the tin lugs [[ed: The microfusion lugs introduced in the 60s helped reduce cost at the expense of beauty, higher weight and less strength through inferior stress propagation.] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Handlebar Position | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The handlebar position is a matter of taste. While it does not generally relate to power it does effect upper body support, leverage for hard efforts, and respiratory limitations while riding. A general rule of thumb is to position the bars to have their ends pointing at the mounting bolt for the rear brake. The wrist should be able to maintain a relaxed grip on the drops. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Brake Lever Location | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The neutral placement for the brake levers is achieved with the brake lever tips in line with the bottom of the handlebar drops. Shimano STI levers seem best from the middle position of the bars, while Campagnolo's Ergopower levers tend to get mounted slightly higher near the top curves of the bar. As long as you can safely reach and operate the brakes from both normal hand positions, strive for the lowest profile that is comfortable. If your stem has the proper extension, and your levers are properly placed, your upper body/back should lean forward at a 45o angle when you're on the hoods. When you move to the drops, your back should be nearly flat, with your upper arms vertical, and the elbows bent at 110°. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Fore/Aft Cleat Position | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Athough some vendors, such as Time with their TBT system, have special devices and markings on their shoes these are not required and are easily duplicated with chalk, shoes and pedal.
While standing erect in your cycling shoes, place a chalk mark on the shoe over the inner ball of each foot. Place the shoe into the pedal with the cleat loosened enough to allow easy fore and aft movement. Position the mark so that it is directly over the pedal spindle. This is the neutral position, best for the majority of riders. There remains a degree of adjustability from this point based upon racing distance, foot size, and riding style. If you have exceptionally long feet or toes for your size, resp. smaller, you may find moving the shoe forward, resp. backwards, of the axle more secure and comfortable. |