Originally Posted by
Grand Bois
I think that most people here understand how to center a wheel.
If you use two of these (or one with a claw), you just pull the wheel back against the stops and the wheel is centered perfectly every time, even in the dark ( or when you don't have your glasses, a new issue for me). I have them on all four of my French bikes because they came with them. I also have them on a mountain bike with a chain stay brake and horizontal dropouts. With those you not only have to center the wheel between the stays, but the brake pads have to meet the rims at the right location. It's a bit of a hassle without those stops, but no problem at all with them.
Never easy to position precisely? I don't get that at all.
Of course riders can center a wheel, which is part of why I said only one side stop is needed. I have encountered riders who, in part because their bikes are so light, end up with chain tension overcoming gravity and with the wheel then not centering with the brake caliper, which is about 90 degrees different from the issue of having the wheel not centered between the chainstays, and is why I suggested applying downward force to the saddle while centering the wheel prior to and while securing nuts or QR lever. This can be more critical when wider axle widths than the frame's actual spacing is used, as is often the case, and made worse by some locknut's un-beveled corners. Such are the banes of cheap bikes, but riders have long been compensating their bike's weaknesses with good habits and practices.
Often enough, using two stops, I've found that they tend to move around, to lose any fine edge of careful adjustment, and not so easy to set both stops precisely in the first place as I said. I'll admit to being finicky about how my wheels are aimed!
And with certain QR levers, as the wheel/axle slides back there can be axle stop contact with the knurl on the nut before there is contact with the axle, which is another source of inconsistent centering when one is relying on two of this kind of stop to allow the sort of slam-and-ride convenience that premium adjuster screws offer.
So as I have tired of having to re-adjust such stops, I say having a stop on just one side is fine with me, since it does at least get the chain-length and chain gap fixed, and so no variations of drivetrain function.