Cogs - Chainrings & Crankbolts


Crystal Designs makes a finely machined chain ring guard. The guard bolts to the outside of the outer chainring on your Mountain Bike crankset. The Crystal Guard is made of 6.7mm thick aluminum plate stock that is machine cut to shape, not die cut. The cutting of the round shape includes 10 pair of half round holes on the edge. These provide an exact grip and edge for all the future machining the plate is put to. The plate is then milled on the back side in a 1/2" wide ring to reduce the thickness by half, providing a gap between the chainring and the plate. On the front side another 1 3/8" wide area is milled away. This reduces the overall weight of the piece and gives it stand-off relief. These stages could have been done in a stamping process, but it would take away from the intrinsic strength of the plate aluminum. Large holes are then drilled through the face, as well as holes for the fixing bolts, which are recessed so there is no need for longer fixing bolts to be provided. The Crystal Guard is then anodized in Black, Lavender, or Silver. They are made in four sizes, one to protect 46 and 48 tooth, another to protect 50 tooth chainrings, a third to protect 42 tooth Micro/Hyper outers and the last to protect 44 tooth Micro/Hyper outers. The large 50 tooth model weighs 192.5 grams, the smaller 46/8 tooth model weighs 172.5 grams. Please be sure to specify size and color.

Size-42-44-46-48 / Color-BK-L-S $ Price in Catalog


For the hard-core thrasher! Do you treat your high-tech mountain bike like a trials bike? Do you like to ride your bike over logs, rocks, benches, small cars, or any thing that gets in your way? If you do, a Rock Ring may save the teeth on your chainrings. This little goodie protects your chainrings from serious damage. It bolts onto your cranks on the outer side of the outer chainring by using longer bolts. The Rock Ring is larger in diameter than the chainring and made of somewhat thicker aluminum. When your chainring would previously have taken a direct hit, with the Rock Ring in place, it will now get the bashing. The beefy serrated edges help you power over obstacles. The 2024-T3 aircraft quality aluminum is strong enough to protect without adding lots of unnecessary weight. The Rock Ring is made from 1/8" (3.188mm or .1255") thick aluminum plate stock that is die cut to shape. After cutting, it's die stamped to create two "breaks" that stiffen the piece and give it depth so it "stands off" or away from your crank assembly. The Rock Ring is then anodized in Black, Lavender, Silver or Blacklight (which is a largely Black with splatter shaped areas derived from anodized resist in Lavender and Blue). Available in three sizes: a small one for 46 tooth outer chainrings (round or oval), and a large one for 48 tooth rings, and an extra-small size for Hyper-C/Micro-D model for 42 or 44 tooth chainrings. The Rock Ring comes with longer length (8mm x .75mm x 14mm) steel chainring fixing bolts. The small Black Rock Ring weighs 122 grams while the replacement bolts weigh 20 grams. Be sure to specify size and color.

Color-BK-L-S / Size-S-L $ Price in Catalog


The Microdaptor replaces the standard inner chainring on cranks using 74mm inner/110mm mid-outer bolt pattern. The smallest chainring possible with a 74mm bolt pattern is 24 teeth, yet there are some riders who like the possibility of using a 28, 30, 32 or 34 tooth low geared rear cog with something smaller than a 24 tooth up front. The Microdaptor allows the rider to use a 58mm BCD Shimano styled Hyper- C type, "compact" inner front chainring. The adapter is CNC machined from 1/4" (.250" or 6.38mm) thick aluminum plate. Arms extend to the 74mm bolt holes, with tapped holes at the inner diameter on the adapter for the 58mm chainring to bolt to. The Avid Microdaptor comes with a set of short length fixing bolts (8mm x .75mm x 6mm) to hold the included steel inner chainring to the aluminum adapter. The aluminum piece comes anodized in Blue, Black, Lavender or Silver. The adaptor comes with either a 20 or a 22 tooth chainring. The aluminum Microadapator weighs 25 grams, the bolts weigh 10.5 grams and the 20 tooth inner weighs 27.5 grams, so the total set weighs 63 grams. Specify color and size.

Size-20-22 / Color-B-BK-L-S $ Price in Catalog, 58mm Stainless Steel chainrings 20t, 58mm Stainless Steel chainrings 22t $ Price in Catalog


This is a set of five inner fixing bolts. They have the standard 8mm by .75mm thread common to all triple chainringed cranksets. They have a 5mm hex head fitting for easy removal. The bolts are 12mm long, and made of chrome plated steel. Also included is the needed set of 4mm aluminum spacers to hold your chainring away from the arm. The five steel bolts weigh 19.5 grams, and the five aluminum spacers add another 3.5 grams.

Steel inner set $ Price in Catalog


SRP has an inner aluminum fixing bolt set made in Massachusetts. The inner bolts have the standard 8mm by .75mm threads. These bolts have a 5mm hex fitting and are 15mm long. They are a direct replacement for any inner bolt set used in any of the cranks reviewed here. Coming as a set of five, these do not come with the needed 4mm spacers, so save the ones that come with the cranks. The set of five bolts weighs only 7 grams, far less than the steel set. The Pro Racing anodizes the bolts in several colors, dark Blue, Black, Lavender, Red, Silver or Turquoise (light Blue).

Color-B-BK-L-R-S-T) $ Price in Catalog


Machined from Titanium 6Al-4V rod, this set of five inner fixing bolts replaces the standard steel ones which come frequently with cranksets. The set has the standard 8mm by .75mm threads to fit all triple cranksets, and have a 5mm hex fixing for easy removal. The set of five can come in one of three lengths, a standard 12.5mm threaded bolt or a long version that is 16.5mm long. Neither set comes with aluminum spacers, you will need to save the ones that come with your cranks. The weight of the 12.5mm long set of five bolts is 9.5 grams, the longer 16.5mm set weighs 11.5 grams.

12.5mm standard, 16.5mm long, 10mm short $ Price in Catalog


This is a set of five nuts and bolts for fastening the middle and outer chainrings on a triple, or both chainrings on a double crankset. The bolts are made of chrome plated steel. They have the standard 8mm by .75mm threads, and are made for flush seating in all chainrings. The bolt's threaded portion is 8.5mm long and has a 5mm hex fitting for easy removal. The nut's threaded portion is 8mm long and they is made of cadmium plated steel with a slot cut in the back for grip in loosening the bolt set. The weight of the five bolts is 14.5 grams, the weight of the five nuts is 11.5 grams, for a total set weight of 26 grams. Made in Japan. $ Price in Catalog


This set of five aluminum fixing bolts replaces the standard steel ones that come with cranksets described above. The bolts are threaded to the standard 8mm by .75mm thread, with the threaded portion being 8mm long. The bolt head has a 5mm hex fitting. The nut portion is also made of aluminum with a slot cut in the back for a grip at time of removal. The threaded portion of the nut is 8.5mm long. The five bolts weigh 5 grams, while the five nuts weigh 4.5 grams, with a total set weight of 9.5 grams. The bolt set is anodized in dark Blue, Black, Lavender, Red, Silver and Turquoise (light Blue). Made in California

Color-B-BK-L-R-S-T $ Price in Catalog


This set of five titanium fixing bolts and nuts replaces the standard steel ones that come with many cranksets. The bolts are threaded with the standard 8mm by .75mm threads. The threaded portion of the bolt is 8.5mm long. A question should arise about how Titanium can be used for both the nut and bolt pieces of this set without them "seizing" to each other as the bolt is threaded into the nut. The answer is the bolt pieces should be coated with an anti-seize compound. The bolt head has a 5mm hex fitting. The nuts are also made of titanium with a slot cut in the back for a grip at time of removal. The threaded portion of the nut 8.5mm long. The five bolts weigh 7 grams, while the five nuts weigh 6 grams, making a set weight of 13 grams. While aluminum nut and bolt sets have occasionally been known to "strip out," with serious pressure, during installation, Titanium bolt sets have known no such failure. Made in USA $ Price in Catalog


This pair of crankbolts are the two that go through the crank arm into the bottom bracket spindle to fasten the arms. These bolts are direct replacements for every three piece crank bottom bracket having a 2 degree tapered spindle we sell. The bolt is threaded to the standard 8mm x 1mm thread pitch, and has a six sided 14mm bolt head on them. The useful threaded length of the bolt is 19mm and the bolts come with matching Titanium washers to evenly pull the aluminum arm onto the B/B spindle. The weight per pair, (with 20.5mm diameter washers), is 16 grams. $ Price in Catalog


These are exquisitely machined from 7075-T6 aluminum rod and ideal for use in a Titanium B/B spindle because they won't need anti-seize. The 14mm head is machined away leaving a lower fixed washer machined in place. In using these bolts, it is strongly suggested that you tighten the arms onto the B/B spindle first using a steel bolt and back it out, then replace the steel bolt with these aluminum ones to hold the arms on in use. They are threaded to the standard 8mm x 1mm thread pitch, with a 14mm head and will replace any crank bolts used by any 2 degree tapered spindle in any B/B in this Buyers Guide. The useful threaded length of the bolt is 17mm and the weight per pair, is a tiny 10 grams. They are made in Arizona. The Hershey ones have tiny American flags Yag laser etched into the top of the bolt head. The TNT ones ahve a "TNT" logo etched in the top. These come anodized in several of colors, dark Blue, Black, Gold, pewter Grey, Lavender, Red, Silver, and Turquoise (light Blue).

Color-B-BK-G-GY-L-R-S-T $ Price in Catalog


When the riders at Syncros wanted a fast easy way to remove and install their cranks, the suggestion of Shimano's One Key Release came to mind. Shimano doesn't make their One Key Release anymore, so they thought about how they could improve the idea and make their own. The Crank-O-Matic set is the result, made of aluminum and Titanium to reduce weight over the original Shimanoversion. The Crank-O-Matic crank arm bolts are machined of Titanium 6Al-4V rod. The bolt has a 6mm hex fitting on its head, that passes through the aluminum crank arm cap. Between the crank arm cap and the crank bolt is a sintered bronze washer to reduce any direct friction. (The sintering process involves bronze dust, impregnated with oil, being put under great heat and pressure, to construct a materially solid washer that has a high self-lubricating quality, so adjoining surfaces slide smoothly). Also included is a pair of sintered washers that seat between the arm and the crank bolt. With the crank bolt tightened into the B/B spindle, and the washer and cap tightened in place over the bolt, a 6mm hex wrench inserted in the bolt can be turned counter-clockwise which pushes against the arm cap and pulls the arm off the spindle without the need of a crank pulling tool. When the arm comes off the spindle, the Crank- O-Matic is still intact in the arm. Re-installing the arm is just a matter of tightening the crank bolt by turning the hex wrench clockwise while threading the bolt into the B/B spindle. This set is well constructed throughout, and complete, it weighs 26.5 grams. $ Price in Catalog


Throughout much of the writing of this section, it has been obvious that a high quality, after-market, replacement crank arm cap has been unavailable. Just three of the crank makers have addressed the need of lost arm caps for expensive cranks, and many of the plastic snap-in types probably won't last more than a few careful removals. John Grafton was the first to attend to this need, at about the time that he had his crank arms made for him by Benson Sim at Sim's. These arm caps are machined from aluminum rod. The end of the rod is bored with a 710 thousandths of an inch deep hole to accommodate the crank bolt head. They are threaded to the necessary 22mm by 1mm threads arm cap hole found on nearly all cranks sold. Using a single slot on the face for removal, this fine pair of crank arm caps weighs just 4 grams per pair. They are available in Blue, Black, 3D Violet (Lavender), or Silver. Sold in pairs, there are frequently long delays in Grafton deliveries to us, as he is better known as a designer than he is a businessman.

Color -B-BK-L-S $ Price in Catalog


Another maker of quality crank arm dust caps is Cook Bros. These came from the need to have a crank cap that had a domed top to fit into and leave curved the Cooks crank arms at the B/B spindle. The cap is 2.5mm thick at the edge and 5mm at the middle so we know the dome rises 2.5mm to it's peak at the center. The interior is hollowed out to depth of 5mm to fit around the crank bolt. The caps have 22mm by 1mm outer threads so they will work in any crankset reviewed in this Buyer's Guide that uses crank arm dust caps. They have a pair weight of 8.5 grams and come in Blue, Black, Lavender or Silver.

Color B-BK-L-S $ Price in Catalog


The Sims caps bear a resemblance to the Grafton caps, and at one time they were near impossible to tell apart. Only recently Mr. Sim has changed the method of removal from a straight slot to a 5mm hex fitting. These lightweight caps are machined from aluminum rod with a tapered outer edge that tightly seals the crank arm cap hole. The caps have 22mm by 1mm threads to fit all the cranks requiring dust caps reviewed in this article. The pair is lightest at just 3.5 grams and they come anodized in Blue, Black, Lavender or Silver.

Color-B-BK-GN-L-S $ Price in Catalog


Park makes a single capable of removing all aluminum/Ti cottlerless crank arms, which includes all the branks sold hear except Bullseye and Grove which don't have a 2¡ degree tapered spindle. The Park tool comes in two parts, a puller and a handle. The puller is threaded on both ends, one side has 22mm x 1mm, the other has 23 x 1mm threads so the tool will fit the inner threads at the B/B spindle. The puller piece is threaded into the crank arm and cinched just past hand tight, the handle piece turns through the hollow core of the puller piece with clockwise rotation. As the handle makes contact with the B/B it applies pressure backward against the tool seated in the arm and begins to push the arm backward off the B/B spindle. The 6.5" long handle is vinyl coated and provides the needed leverage to free even the most stubborn arm. This tool is a must have for anyone using a cotterless crank intending to work on their bottom bracket and not wanting to damage their arms in removal. $ Price in Catalog