Alligt chainrings 110 / 130 BCD

Alligt manufacture large sized chainrings for use to achieve higher than normal gear ratios. These are especially useful on small wheel upright bicycles, such as Moultons, but also on many recumbents.

For example, a normal 52 tooth chainring combined with a 13 tooth rear sprocket and a 27 inch rear wheel gives a ratio of 108 gear inches ( = 52 / 13 * 27 )

With a 20 inch rear wheel, the same gearing gives a ratio of just 80 inches, which is not high enough for fast riders.

Changing to a 65 tooth chainring allows a gear ratio of 100 gear inches with a 20" rear wheel, which is more than enough for most people.

The chainrings are also available in smaller sizes, down to 39 teeth, so can also be used to adjust gear ratios downwards.

These chainrings are manufactured from one piece of 6082 aluminium, including the guard which helps to keep the chain on such a large chainring.

The mounting holes are on 110 and 130 mm BCDs. Both 110 and 130 are used for good quality "road" chainsets. The distance between each of the five holes and is 64.6 mm for a 110 BCD crank and 76.4 mm for a 130 BCD crank. See the additional images for an explanation of what this means.

70 tooth plastic chainwheel

Alligt's 70 tooth chainwheel is moulded in a high quality hard plastic and has a double chain protector. This part has the advantage of being 20% lighter than an equivalent aluminium part. Calculations suggest that this new product will outlast at least two chains. While the aluminium chainwheels have a long pedigree, this new part is still an experiment which customers can help to test. If found to be successful then other sizes will become available made from the same material. Note that the crank shown in the photo is not delivered with the chainwheel, but it can be fitted to either a 110 or 130 BCD crank with five equally spaced arms.

Calculating overall size of the chainring. Read this before ordering.

We're often asked for the overall size of these chainrings. Actually this is easy to calculate within a few mm so please take the time to calculate it before you order a chainring so that you know it will fit your bicycle.

Bicycle chains have a pitch (distance between links) of 1/2 inch or 12.7 mm. The circumference of the chainring in mm can be calculated as the number of teeth multiplied by 12.7 and the diameter results from dividing this by PI.

Therefore a 70 tooth chainring will have a circumference of 889 mm and a diameter of 283 mm or just over 11 1/8 inches. In practice the chainrings are a little larger. A about 10 mm to this to allow for the height of the chain and the chain "keeper".

Overall diameter in mm = teeth * 12.7 / PI + 10

Overall diameter in inches = teeth * 0.5 / PI + 0.4

Weight

A 60 tooth 130 BCD chainring weighs about 170 grams. Larger or smaller chainrings will vary proportionately to their size.

Appearance

The appearance of the chainrings varies depending on sizes and specifications. See the additional images.