Sims & Rohm Lineright
SIMS & ROHM LINERIGHT
CW EVALUATION
Help for your chain, gang?
ADJUSTING YOUR MOTORCYCLE’S DRIVE chain is not as easy as it may appear. Get it wrong, and your bike could suffer premature chain and sprocket wear, as well as a possible loss of stability and handling.
Motorcycles do, obviously, have provisions for chain adjustment, including little reference marks on both sides of the rear axle; but due to what is called a “stack-up” of tolerances in the manufacture of all the components between the rear-wheel sprocket and the countershaft sprocket, those reference marks are no guarantee of proper chain alignment.
Sims & Rohm (3120 Industrial Dr., Yuba City, CA 95993; 916/674-9123) claims to have the cure: The LineRight, an $80 special tool, is said to ensure drive-chain alignment. The all-aluminum LineRight is a 37-inch-long rod with an adjustable pointer on one end that slides in and out, and a second pointer that adjusts by sliding along the length of the rod. Each pointer has a cone-shaped tip on the end that fits into the hollow-center swingarm-pivot and
rear-wheel axles on many motorcycles. If your bike’s axles don’t have such holes, you need to make a small indentation in each one, or send them to Sims & Rohm, who will drill them free of charge for LineRight owners.
To use this alignment tool, you first insert one of its pointers into the center of the swingarm-pivot shaft, then adjust the other pointer until it fits exactly into the center of the rear axle. (On bikes fitted with exhaust systems that run parallel to the swingarm, the pipes must be removed before the LineRight can be put in place.) Next, tighten the knurled locking knobs and take the LineRight around to the other side of the motorcycle, then try to insert the pointers into the axle and swingarmpivot holes. If the pointers fit perfectly, the chain is properly aligned along the front and rear spockets, says Sims & Rohm; if they don’t fit, you simply adjust the rear wheel until they do.
Unfortunately, there are some fundamental flaws with the LineRight. For one, all it does is ensure that the swingarm axle is parallel to the rear-
wheel axle, even though neither one of those components has any bearing on the location of the countershaft sprocket. Consequently, the tool cannot ensure sprocket alignment.
What’s more, for most chain-driven bikes, particularly those designed for roadracing or high-speed sport riding, wheel alignment is more critical than chain alignment. And while Sims & Rohm makes no claims about wheel alignment, it’s important to know that the LineRight also doesn’t allow you to align the front and rear wheels during chain adjustment.
All the LineRight does, then, is allow you to check the accuracy of the chain adjusters’ reference marks and recalibrate them if necessary-something you could do for free with a tape measure and a little patience. Once those marks are verified, they need never again be checked unless the bike is crashed or one of the affected components is replaced.
Our recommendation is to save the 80 bucks for something that’s more useful-say, a new chain. É3
