Bicycle Seat Posts 101

Diameters

Vary from about 25.8mm to 31.8mm. The seat post diameter has to match the seat tube’s inside diameter. Older European and Japanese aluminum frames, and ancient steel frames generally use the smaller diameter seat posts. Modern oversized aluminum frames have thinner seat tubes which require fatter seat posts to fill the hole. Classical steel frames use seat posts ranging from 26.2mm to 27.4mm, with 90 percent of them 27.2mm.

Lengths

From 180mm to 400mm. Road bike seat posts are shorter than mountain bike seat posts, but if you have a super long mountain bike seat post, you can still stick it into a road bike. If the extra length and few extra grams bothers you, chop it off.

Insertion

All seat posts have a minimum insertion mark. Sometimes it’s a maximum height mark–two names for the same thing. In any case, you have to make sure 65mm are inserted into the seat tube.

One-bolt clamps or two bolt clamps?

Think about it. If you’re holding a long beam above your head, clasping it with one hand, you’d best have a tight grip, or it’ll fall. Hold it with two hands, and your grip can relax dramatically.

One bolt posts are generally adequate and don’t take that as a backhanded endorsement. The best ones hold fine. The worst don’t.

One bolt posts are quicker to set up, but that’s more of an advantage to a bike shop guy trying to build his daily quota, than it is to you.

Two-bolt posts have a mechanical advantage (as noted above), but cost more to make, and take longer to set up, and that’s why they’re not as common.

SPO (Seat Post Offset)

SPO is how far the clamp sits behind the center of the post, and it’s an issue because it affects your saddle position. Most riders like to “sit behind” the pedals, and that requires putting the saddle as far to the rear as the seat post allows. A post with no offset (no SPO) doesn’t allow this.
Triathletes are the exception. They generally sit forward on the saddles, a position that works for them in tandem with the funny handlebars they like.

Bicycle Shifters 101

Road Bike Shifters

Downtube shifters

The traditional, classic road shifter. Favored for its lightweight, simple set-up, and short cables, which, back in the ‘60s and ‘70s riders believed made for quicker shifts due to less cable stretch. Modern cables don’t stretch enough to notice anyway, and speedwise, downtube shifters are the
slowest simply because you have to move your hand down there to get at ‘em; but they remain the favorite style among those who still favor them for a few other reasons:

  1. They look good. They’re isolated from the brake levers and handlebars, so they don’t muck up that part of the bike. They add something, visually, to the downtube, the longest tube on the bike, and one that looks lonely with nothing on it.
  2. They’re the lightest.
  3. They’re the cheapest to buy.
  4. In these days of late-entry riders willing to spend lunatic amounts of loot for overpriced, high-tech convenience shifters, some riders like the message downtube shifters send—that they’re comfortable enough on a bike, and experienced enough, to be able to remove one hand from the bar to shift; and that they realize muscle, not frenetic clicking, is what gets you over the hill.
Bar-End Shifters (BES)

Sometimes called “fingertip shifters” or “bar-con (control) shifters.” Introduced in the early ‘50s as an alternative to the downtube shifter, but never really won favor with the hardcore racers of that or any period. In the old days, racers said things like “cables too long, too much stretch!” and BES took hold only among tourists, tandem riders, and cyclo-cross racers, all of whom realized it was a good thing not to have to take your hands from the bars when controlling a heavily loaded bike or racing over rough terrain.

Compared to downtube shifters, BES are:

  1. heavier
  2. less aerodynamic
  3. more expensive
  4. more of a hassle to set up

But the differences are minimal in all cases, and the convenience they offer—halfway between that of a downtube shifter and a modern STI/ERGO shifter—makes a lot of sense without selling out completely and giving up simple mechanical design for convenience at all costs. It’s a good balance, smart.

BES are increasingly rare these days, and are kept alive only because triathletes and time-trialists use them on the ends of their funny bars. Campy and Shimano still make them, but the best ones we’ve used are the Supermix shifters shown in our print catalogue.

Shimano STI

STI stands for “Shimano Total Integration,” and refers to Shimano’s preference for integrating (or combining, or linking) previously separate bicycle components so that 1) If you buy one, you get the other; and 2) You can’t use one without the other. The STI program is double-edged. On the one hand, it is a pro-consumer/rider program that protects you from incompetent product managers/manufacturers who might otherwise put incompatible parts on the same bike. On the other hand, it is a way to prevent smaller, less-well-capitalized manufacturers from selling their parts to high-volume manufacturers. Back in 1986, almost all bike makers spec’d Shimano shifters, but a whole lot of them also spec’d Dia-Compe brake levers, which were clearly more desirable. Consequently, Shimano was left with millions of unsellable (for good reason) brake levers, and that—not answering a consumer demand for more convenience—was the impetus behind the next year’s STI. Riders who like STI, like it because they don’t have to move their hands to shift. You can access the shifters when your hands are on the brake lever hood/body, or from the drops. So, despite its shaky origins, it fullfills a need for some cyclists.

Behind the left brake lever is a secondary lever which moves inward with a push, shifting the front derailleur.

Behind the right brake lever is a corresponding secondary lever for the rear derailleur. Push it inward (toward the front wheel), shifting the rear derailleur.

STI braker/shifter units are heavier than a solo brake lever, but often weigh no more than an uncombined brake lever and shift lever. The brake lever bodies, where you spend most of your time, are irritatingly ergonomically perfect, at the expense of aesthetics. They are bulkier, and cyclists used to slender, compact, and nicely curved bicycle parts find them ugly, cyclops-looking units.

STI shifters don’t have a friction-shifting mode, and require Shimano-compatible derailleurs and gears. For someone starting out with all fresh stuff, that’s not a problem, since virtually all currently manufactured cassettes and freewheels are Shimano-compatible (just as most computer software is MicroSoft compatible).

Campagnolo ERGO shifters

Are Campy’s answer to Shimano’s STI. Campy went into ERGO reluctantly, and only after it was clear that downtube and bar-end shifters were not the way to capture new markets. ERGO shifter/levers have thumb-tabs mounted fairly discretely on the inside of each brake lever body, and Shimano-like secondary shift levers behind the brake lever.

To shift the front derailleur to a bigger chainwheel, push the secondary lever inward, toward the front wheel (same as with STI). To shift from a large chainwheel to a smaller one, push the thumb-tab down.

ERGO’s front shifting is non-indexed, which makes it compatible with anybody’s front derailleur, a good thing. Front shifting with ERGO tends to be slightly slower than with STI, although many people still prefer it.

To shift the rear derailleur to a larger cog (easier gear), push the right-hand secondary shifter inward. To shift to a smaller (harder) cog, push down the thumb-tab.

Cosmetically, they’re an improvement over STI, because the cables don’t exit the levers sideways, and the levers look pretty normal from the front (no “cyclops” look). Functionally, they’re Shimano’s equal. Certain shifts are made faster by STI, others are faster by ERGO, but in the areas of speed and convenience, both have plenty to offer even the most shifting-obsessed rider. Most people like to defend what they own, and sell their friends on it, but anybody who badmouths the function of either STI or ERGO has become too dependent on technology for their own good, and probably couldn’t write a letter to a friend without a keyboard and email.

Kelly TakeOffs

If you like the convenience of STI and ERGO, but don’t like the expense, the limitations, or the whole idea of buying into technology that was ill-born in the first place and now just feeds on itself (not to imply that there’s anything wrong with that); then get Kelly TakeOffs. (www.Kellybike.com).

Invented by Oakland, CA resident Chris Kelly as an alternative to STI and ERGO, this is one small-company gimmick that really works. The TakeOffs are tubular steel mounts that on one end attach to the handlbars under the brake lever bodies, and at the other end, allow you to mount any old downtube shifter inboard of the brake levers, so you can shift while grasping the brake lever hoods, or down in the drops, or with your hands on the top ofthe bars. In other words, from more positions than either STI or ERGO. What’s more, since the lever position is visible and changes according to what gear you’re in, you get a visual indication of the gear, just as you do with downtube shifters or bar-end shifters. ERGO doesn’t do that. STI does it if you get the fancy version, but you have to read a dial, and if convenience is your end-all, that’s not as good as glancing at a lever and thinking “I’m just about maxed out back there.”

Another wonderful thing about TakeOffs is that most downtube shifters have a friction option, so you needn’t completely give shut off the portion of your brain that controls things like sensitivity and feedback. What’s more, in friction mode, you can use any derailleur with any chain or freewheel or cassette. Finally, the levers are so accessible that any supposed benefit of indexing virtually vanishes—the lever are right there, so easy to dial in,that it’s no inconvenience at all. It’s not the hurdle it is with downtube shifters (not a huge hurdle with them but one many riders would rather not jump, anyway).

Functionally, TakeOffs with downtube shifters work the same as downtube shifters, in that you pull the left one back to shift a front derailleur outward, to a larger (higher gear) chainring; and you pull the right one back to shift to a larger (lower gear) rear cog.

The only drawback to TakeOffs is that the tube that exits from the underside of the brake lever sort of interferes with a normal grip, the one with your fingers curling underneath the brake lever body. It’s not a huge deal—there’s still room there, but on any other brake lever, there’s nothing there, and on the TakeOffs, there’s that dang tube. You get used to it easily enough, and if the other benefits appeal to you, don’t think twice, it’s all right.

Sidepull Brake Calipers 101

Sidepull brakes are good for skinny to medium road tires, up to about an inch and a quarter wide. They connect directly to the brake lever by a cable and housing, so the frame doesn’t need any extra cable stops or hangers, as is the case with cantilever brakes. Most mechanics, whether they’re pros or novices, find sidepull brakes easier than cantilvers to set up, adjust, and maintain.

Sidepulls aren’t good for fat tires, because fat tires don’t fit under the arches.

Also, they aren’t as fender-friendly as cantilevers are, for the same reason, although if the frame designer does his or her job right, and you pick the right sidepull and don’t go too fat on the tires, you can fit fenders under them.
There are two main types of sidepulls: Single Pivot and Dual-Pivot

Single pivot sidepulls offer more fender clearance than do dual-pivot styles, and are lighter, but they aren’t as powerful. If you’re really heavy, or ride a loaded bike downhill, or have weak hands, or any combination thereof, a dual-pivot is better than a Single-pivot style.

Dual-Pivot sidepulls offer the simple set-up of any sidepull, but approach cantilevers in power. The price they pay is more weight and less fender clearance. Dual-Pivot sidepulls have virtually taken over, and the only Single-pivot styles still available are NOS (new old stock) made in the pre-Dual-pivot ’70s and’80s.

Brake Reach

Brake Reach is the distance from the centerbolt to the center of the brake pad when that brake pad is at the bottom of the slot. (Brake calipers have vertical slots that allow you to move the brake pads up or down, so they mate with your rims perfectly.)

Short reach brakes typically “reach” up to 49mm, sometimes 50mm from the brake bolt.

Standard reach brakes (usually called Long Reach these days; but in the old days they were standard, so the name sticks) reach up to 56 or 57mm. The increased reach allows the frame maker to make a longer fork and place the rear brake bridge higher on the seat stays, which gives more room for fenders or fatter tires.

How They Attach: Allen nuts or Hex Nuts?

Brakes attach to the fork crown and seat stay bridge with a threaded bolt, which is secured by either a standard hex nut (“nutted”) or an allen nut (“allen”).

Nutted brakes were the old way, and are still the easiest kind to use if you’re attaching fenders; but not by much. Some riders point out that nutted brakes are safer because you can tell by looking if the nut comes loose. Allen nuts are generally coated with a Loctite-type goop that prevents them from vibrating loose, though, so just snug them up tight when you install them, and don’t worry about it after that.

Stems 101

Anatomy

quill – the portion that fits into the fork’s steer tube, providing the connection between handlebar and front wheel. There are two important quill dimensions: diameter and length.

On modern decent-or-better bicycles, quill diameters vary from 22.2mm (7/8-inch) on traditional/normal bikes, to 25.4mm (1-inch) on burly mountain bikes and many tandems.

Quill lengths are measured from the bottom of the quill to the top of the quill, and vary from 125mm to 280mm. The traditional-length road stem quill is 135mm long. Stems start to look funny up around 200mm.

extension – the part of the stem that extends forward to the handlebar clamp. Some manufacturers measure extensions from different points than other manufacturers, but nominally, it’s from the center of the quill to the center of the bar clamp. The shortest extensions are 50mm; the longest are 140mm.

handlebar clamp – the part that actually grabs ahold of the handlebar.

Some clamp with one bolt, some with two, it doesn’t matter. What matters is diameter, and there are two common ones.

25.4mm (one-inch): For old cheap road bars and all mountain bikes. 26.0mm: For most modern road bars.

MATERIALS

Aluminum, Steel
The “classic” aluminum stem is cold-forged, shiny, slender, smooth, and has an angle (measured between the quill and extension) of 72 to 73 degrees. Cold forging is a process in which a solid bar of aluminum is bent to the desired angle, then smashed into shape between forging dies. It is called cold-forging, not because the aluminum is cold when it takes place, but because in another process, called HOT forging, the aluminum is much hotter. It should be “warm forging,” but it’s not.

Cold forging does good things. Mainly, it imparts a grain to the aluminum, not unlike the grain in wood. More importantly, in cold forging, the grain follows the contours of the aluminum, exactly as it does in a crooked tree branch. That contoured grain adds incredible strength to the piece.

Cheaper stems are cast; a process in which molten aluminum is poured into a mold. There are two common casting techniques.

The “good” way is Gravity Casting: After the aluminum is poured into the mold, the pre-stem is allowed to cool naturally (slowly), during which the bubbles in the liquid aluminum gravitate to the top and are expelled, leaving a fairly dense (though grainless) cast stem. Gravity cast stems are not as strong as cold-forged ones, but they’re still pretty good. Certainly strong enough for road use.

The worse way, Pressure Casting, starts out the same as Gravity Casting, but instead of letting the bubbles float up and out of the mold, the aluminum is subject to external pressure, intended to force the bubbles out; and then it is force-cooled. Pressure cast stems are strong enough for most uses also, but are more brittle than either Gravity Cast or cold-forged ones.

TIG-Welded
Aluminum can also be tig-welded. Usua

Steel Stems
Are usually TIG-welded

Dimensions
Quill

Bike Saddles

Saddles come in more variety than any other bicycle component. Plastic, leather, wide, skinny, holes for preventing impotency, no holes for preventing impotency, embroidered racy/midlife crisis saddles, tilting saddles, hammock saddles, and no doubt new and revolutionary designs are being developed right now.

A saddle should be:

  1. Wide enough to support your sit bones (ischial tuberosites, pronounced “ishi-ul tuber ossitees”). They’re called sit bones because you’re supposed to sit on them. If it is too narrow, your sit bones will straddle the saddle, and the saddle will push up into you. If you’re a woman, it’ll crush your folds. If you’re a guy, it’ll smash your penile artery, and make your penis go numb. It is our opinion that 170mm is wide enough for all men and 70 percent of women, although “women’s specific” saddles are usually about 220mmm wide.
  2. Skinny enough in the mid portion so your thighs don’t rub it and get all chafed. How skinny is skinny enough depends on how you pedal, how fat your thighs are, and your pedaling position. The more upright you are, the wider the saddle can be.

Men’s saddles are longer, front to rear, than are women’s saddles. The added length supports the external plumbing.

Women’s saddles are usually wider in the rear, because women’s sit bones are wider (designed for giving birth). Women’s saddles usually are shorter front to rear, because they have no external plumbing to support.

Materials

Leather is the traditional saddle material. It looks the best. It smells the best. It usually weighs the most, requires 100 miles of riding to break it in, and a certain amount of maintenance.

If the prospect of breaking it in and maintaining it scares you, get a plastic saddle. If you go through several plastic saddle saddles and still aren’t comfortable, get a Brooks B.17.

Plastic-base saddles are far easier and faster to make, and if they’re shaped right and padded properly, they work well for most people. They require no break-in or maintenance, and that always appeals to a certain number of riders. They’re the most popular kind, because they can be mass produced cheaply, leaving plenty of money remaining to promote and sell them.

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