I just got a new Nimbus II 20 with ISIS cranks. I have noticed that the left crank is not the same distance from the frame as the right crank. Is this normal or does it need to be corrected?
To confirm what the problem is I took the wheel out of the frame and measured the key dimensions, see below. Dimensions are in inches.
Distance from inside bearing edge to hub flange:
Left side = .685, Right side = .680, Delta = .005
Distance from inside crank arm to outside edge of bearing:
Left side = .180, Right side = .065, Delta = .115
I am assuming that this is from either, torquing the right harder than the left, or it is from manufacturing tolerance/error.
Does anybody have any insite on this, and should I have this corrected?
Yes, I was going to say the short answer is that .115" is not enough to notice or worry about. But on the other hand, a guy thorough enough to calculate the .115" in the first place might be a meticulous guy who wants perfection. In that case, I’m not sure what’s the right way to make it perfect, but I’ll add that riding the thing may tend to make it imperfect anyway.
ride with it and dont complain. make sure the cranks are tight enough though.
i modded my profiles to fit the hub better by taking off a spacer so the left crank is closer to the bearing than the right it. and i dont notice the difference
it isn’t a big error, but if it doesn’t have shims, one has been taken off and put back on, or is noticably cranked down harder, also, bearings move quite a bit if there are no shims.
I took the retention bolts out of the crank arms to compare.
The right arm is tightened to the point were the bolt washers bottom out with the hub.
The arm has .115 inch seperating the end of the hub and the bottom of the crank rentention bolt bore.
This tells me that the Right arm is either overly cranked on or deffective, or the right side of the hub is defective. I say this because there is no more space to thighten the Right arm if it ever comes loose. We all know it will come loose with use.
Before I thought you were just being picky but now I think that you truly found a defect that is worth a complaint and a replacement from whomever you bought it from. If you get that replaced now you might have just saved yourself a headache.
Try swapping over the cranks to see if the right crank bottoms out on the left side, or the left crank bottoms out on the right side. That’ll tell you where the problem is. (Don’t ride it though, or your pedals will fall off).
If it’s the crank, then tell the people you bought it from, and ask if they want to send you a new crank - If they are happy with it, and it becomes a problem a few months down the line, then you can go back to them, point out that you reported it at the time, and you should get it replaced.
If it’s the hub, then I’d ask for the whole thing to be swapped. You don’t want to be messing about relacing wheel to change a hub if it starts to play up.
The problem is that the cranks were installed without the spindle crank spacers.
This spacer slides over the spindle, rest against the inner bearing race, and creates a stop for the crank to rest against. This causes the crank to always be the same distance from the center of the hub. A great feature. Unfortunately, if it is not included and the cranks are torqued down you will will deform the cranks.
Fortunately, I called Unicycle.com and told them what the problem is and they are sending me new cranks, crank bolts, and the missing spindle crank spacers. Yeah!
