Can someone explain dropouts to me ?
 

I built a Lynskey Urbano with front and rear thru-axles a year ago. Everything good until a month ago when my bike began making a squeaking sound when I pedaled hard. I couldn't reproduce this in the bike stand. I tightened every bolt I had placed in the bike, checked chain rings, derailleurs, lubed the chain. Nothing helped. All the bolts I had placed were fine. Then I noticed the drive side rear wheel dropout was loose. I tightened it and NO SQUEAK. Problem solved. I never really thought about dropouts before because the frame came with dropouts installed. I trusted that they had correctly torqued the bolts (big mistake !). Anyhow, in looking at the dropout I realize I don't quite understand their nature.

Why does Lynskey sell the dropouts with six different nuts ? Why would you need an indexable nut set ? Would that only be to adjust the angle at which the thru-axle stops when the axel is fully tight ? Don't most thru axles allow you to turn the handle without tightening ? And what does the set screw do ? Does the set screw just hold the nut in place ?

Thanks.

https://cdn3.bigcommerce.com/s-m0s28...60.640.jpg?c=2

you ask Lynskey ? what did they say?


[edit] reply below makes sense ,, :innocent:





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In most of those nuts, the hole is off center by a differing amount, to allow the rear wheel to be aligned in the frame. Welding frames causes the metal to shrink and pull in varying degrees depending on the amount of filler metal added, fit tolerances, etc. Thru axles are not tolerant of the misalignment that welding can cause and there is no way to adjust them after fabrication. The eccentric(or off-center) nuts allow the drive side dropout to be moved forward/back/up/down as necessary to correct the alignment. This appears to be Lynskey's own version of the Syntace thru axle system, which uses similar eccentric nuts and a pinch bolt.

Not disagreeing with you, but that is not something I've ever had to contend with in a regular fork or rear vertical dropout - I've never adjusted the centering of the wheel in the dropout or noticed that the dropout had been modified after welding. Why would this be a problem for a through axle when it isn't for a regular axled bike?

When building a frame for QR axles, one dropout can be filed to correct any alignment issues. It doesn't always happen and its usually only around .5mm that gets filed off, so not a noticeable difference. With thru axle dropouts, you can't file to correct alignment, so the eccentric inserts can save a frame from the scrap pile. I have only built a few thru axle frames that didn't have adjustable rocker dropouts and none of them needed correction after welding, but I'm not building frames in a production setting.

Fwiw,
 

NB: going from Lynskey TA specific to a generalization now.. :innocent:

Considering the dropout uses a removable hanger, couldn't they just finish machine the dropout for the hanger last?

Anything is possible, but it would be very difficult to fixture a complete frame to machine that dropout. I'm surprised that Lynskey sends out all of the different variations of the nut. I would just find the one that works and ship the frame with it already installed in the correct position. It is also possible that Lynskey is providing nuts with different thread pitches, so the buyer can choose which style axle to use. However, there are only 3 commonly used 12mm thread pitches and the picture on the Lynskey website clearly shows an insert with an off-center nut installed.

You are right. When I bought my frame it came from Lynskey with the TA dropouts installed. Only one nut. That's why when I went to their website to look at the dropout, I was surprised to see all the different nuts. I only went to the website to better understand dropouts when the bolts holding them came loose.

Very interesting. I totally missed the off-center nature of the nuts. The eye doesn't perceive what the mind does conceive !!!

Thank you !

Your other questions have been answered but this one has not. Shimano's cam action thru axles do not allow you to turn the lever when the axle is tight hence the indexable nut.

https://cimg3.ibsrv.net/gimg/bikefor...b1ddcb87da.jpg