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-   -   Thread engagement (https://www.bikeforums.net/singlespeed-fixed-gear/1158389-thread-engagement.html)

bonsai171 10-19-18 07:15 PM
Thread engagement
 
https://cimg6.ibsrv.net/gimg/bikefor...3a902118a0.jpg
I recently had my rear hub serviced by a bike shop, and just replaced the nuts too since they were worn. When I threaded the nut onto the axle, it doesn't go on all the way. Is it unsafe to ride like that?

Dave

taras0000 10-19-18 08:32 PM
You're ok if the first 3-4 threads are engaged. This is where most (roughly 90%) of a threads holding power is, even on deeper engagements. Ideally, you want minimally 1-2 threads showing past the nut. This is the standard minimum for bolted connections in the industrial world.

Also, is it a new axle? and are the thread engagements the same on the other side? If it's short on both sides, methinks that maybe they installed a bolted track axle on a road width hub, since it's a conversion. In other words, the axle is too short by ~3mm on each side.

Gresp15C 10-19-18 09:45 PM
The picture looks like it's taken from the NDS, so it must be a flip-flop hub. Is that right? Are there extra spacers or washers that don't need to be there? Otherwise, I've found that longer solid axles are readily available, just have to be sure of matching the threads. Also, see the thread about track nuts -- the ones with floating washers are indeed preferable, but might have less thread engagement unless you have a longer axle.

bonsai171 10-20-18 12:39 AM
Originally Posted by Gresp15C (Post 20624889)
The picture looks like it's taken from the NDS, so it must be a flip-flop hub. Is that right? Are there extra spacers or washers that don't need to be there? Otherwise, I've found that longer solid axles are readily available, just have to be sure of matching the threads. Also, see the thread about track nuts -- the ones with floating washers are indeed preferable, but might have less thread engagement unless you have a longer axle.
It is a flip flop hub. Before the service, I had the axles going all the way thru on both side if I remember correctly. As far as I know, they just lubed and adjusted the bearings. One side has the axle going all the way thru the nut (fixed side), and the other side is what you see in the picture. Should I bring it back to the shop for adjustment, or just leave it alone? The one side had 2 nuts on it, so maybe 1 can be taken off?

Dave

bmwjoe 10-20-18 06:25 AM
Originally Posted by taras0000 (Post 20624817)
You're ok if the first 3-4 threads are engaged. This is where most (roughly 90%) of a threads holding power is, even on deeper engagements. Ideally, you want minimally 1-2 threads showing past the nut. This is the standard minimum for bolted connections in the industrial world.

Also, is it a new axle? and are the thread engagements the same on the other side? If it's short on both sides, methinks that maybe they installed a bolted track axle on a road width hub, since it's a conversion. In other words, the axle is too short by ~3mm on each side.
I agree with the above. However, we could help you out better if you showed both sided. Are there two nuts on the other side? This is strange. You may just need to have the axle adjusted so it is even on both sides with one nut. Perhaps something is wonky with the axle and it will only work when pushed to one side. Send a picture of the other side please.

bonsai171 10-20-18 07:06 AM
Originally Posted by bmwjoe (Post 20625094)
I agree with the above. However, we could help you out better if you showed both sided. Are there two nuts on the other side? This is strange. You may just need to have the axle adjusted so it is even on both sides with one nut. Perhaps something is wonky with the axle and it will only work when pushed to one side. Send a picture of the other side please.

https://cimg2.ibsrv.net/gimg/bikefor...67c7b89883.jpg

seamuis 10-20-18 07:22 AM
Are we working under the assumption that you have a 120mm hub and 126mm frame spacing?

bonsai171 10-20-18 08:34 AM
Originally Posted by seamuis (Post 20625153)
Are we working under the assumption that you have a 120mm hub and 126mm frame spacing?
That's what it looks like. I think when they serviced the hub they shifted the axle more to one side, so now the difference is easier to see. Maybe the lns can shift it back and even it out.

Dave

TejanoTrackie 10-20-18 08:55 AM
Looks like maybe you should get the LBS to install a longer axle.

seamuis 10-20-18 09:02 AM
Originally Posted by bonsai171 (Post 20625212)
That's what it looks like. I think when they serviced the hub they shifted the axle more to one side, so now the difference is easier to see. Maybe the lns can shift it back and even it out.

Dave
the axle shouldn’t have been shifted at all. On a track hub, the axle should be centered. Remove the wheel from the bike, remove the axle nuts and measure the section of axle on both sides. You should be able to tell immediately if it’s not centered, but you should measure it anyway. Also, make sure there are no axle spacers on either side before measuring. An axle spacer, if present should simply slide off. there’s no plausible reason for the axle to have been shifted, as I said, so if the LBS did this when servicing, then they should fix it. If you measure it and it’s off center, take it back and show them. Have them recenter the axle.

id be very surprised if this isn’t the issue


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