Author Topic: built in chain tensioners damage the axle?  (Read 449 times)

Offline mal

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built in chain tensioners damage the axle?
« on: February 25, 2020, 09:07:17 PM »
I came across this video today https://www.youtube.com/watch?v=8oQKR7r4HzY
with a mod to protect your axle from the chain tensioner.
Do built in chain tensioners damage the axle?
As i just bought my first frame with built in chain tensioners i was wondering if i should apply that mod..

Offline Revig

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Re: built in chain tensioners damage the axle?
« Reply #1 on: February 26, 2020, 10:20:32 AM »

exactly, with this kind of build in tensionner, it could happen that the thread of the axle hub can be damaged by the end of screw. It will for sure happen if you screw the tensioner screw strongly while the hub is already in place (hub nuts already tightened). But it could happen also because the bike will get many occasions to fall and get some shocks and so on while using it flatlanding (that's another reason to firmly tight the rear hub nuts basicaly).
So this kind of mod is smart to prevent the issue

Offline mal

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Re: built in chain tensioners damage the axle?
« Reply #2 on: February 26, 2020, 08:33:36 PM »
yeah,i can understand the logic..
what about completely removing the chain tensioners after you have tightened the wheel?

Offline DaddyCool

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Re: built in chain tensioners damage the axle?
« Reply #3 on: February 26, 2020, 11:31:36 PM »
The threads on the rear axles on my bikes with these chain tensioners (which I still like a lot) are slightly damaged. It may cause problems when I need to remove the cone nuts...
I like the idea presented in this video.I think it is correct what Revig says: When your bike falls, it can cause additional force on the axle. This would be not the case if you would remove the bolts, but then you lose the advantage that your wheel stays in place. This is one of the main benefits of the chain tensioners beside the good adjusting option: The wheel stays in place! My experience is that however you tighten your axle nuts, it will always move after some time. With the chain tensioners this is reduced a lot!So I would not remove the chain tensioner bolt and maybe apply this protection piece shown in the video.

Offline mal

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Re: built in chain tensioners damage the axle?
« Reply #4 on: February 27, 2020, 12:28:55 AM »
i think i might try it too..!

Offline ortho

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Re: built in chain tensioners damage the axle?
« Reply #5 on: February 27, 2020, 04:26:29 PM »
I remember when Sunday BMX first started putting tensioners in the dropouts, they said they used a softer metal (maybe aluminum?) for the screws than the steel of most axles, in order for the axle not to get chewed up. Not sure if it worked. My frame came without the screws and I just used regular steel screws and they totally ruined my freecoaster bolts in like the first week.

Offline mal

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Re: built in chain tensioners damage the axle?
« Reply #6 on: February 28, 2020, 09:02:08 PM »
It was making contact with the bolts,not the axle?
Must have been of the ones that are not going through the dropout,i guess..
Makes total sense to use a material softer than the axle,they (the companies) should know that.

Offline ortho

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Re: built in chain tensioners damage the axle?
« Reply #7 on: February 28, 2020, 10:28:05 PM »
It was making contact with the bolts,not the axle?
Must have been of the ones that are not going through the dropout,i guess..
Makes total sense to use a material softer than the axle,they (the companies) should know that.

Sorry, i should have said my freecoaster has a female axle so it was the (male) bolts that had the thread that got chewed up by the tensioner screw in the dropout.

Offline jerky

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Re: built in chain tensioners damage the axle?
« Reply #8 on: February 29, 2020, 10:26:39 AM »
I came out of a long hiatus from riding last summer and the new rig I built was an Intrikat with those similar built in tensioner screws. A lot of these kind of design advancements were all new to me so I didn't think too much of it at the time when I was building the bike. After riding it a bit and taking my back wheel off a few times to play around with slack adjustment, I noticed the tensioner screws were mangling the threads a little and the jam nuts were a bit difficult to take off when it reached the mangled section. To remedy that, I happened to do a similar thing but instead I used something else I had laying around the house in abundance, 1/2" diameter copper water pipe. The 1/2" diameter water pipe fits a 14mm axle diameter axle perfectly and the copper is very easy to work with. First I cut a slice of pipe a little less than the width of the dropout with a pipe cutter and then used diagonal wire cutters to snip the copper pipe slice into small crescents similar to the video. I bought a M14x1.0 die to clean up the threads on the axle before reassembling everything and putting the copper "crush spacers" in place. The photo attached is my first attempt that ended up being a bit too wide. I cut a slightly narrower one and also rounded the sharp edges with a Dremel. The copper crush spacer has been doing a great job at protecting the threads from any further damage.

Offline DaddyCool

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Re: built in chain tensioners damage the axle?
« Reply #9 on: February 29, 2020, 10:44:28 PM »
Hi jerky, it really makes sense what you describe here! Now I am thinking of doing this mod as well...

Offline jerky

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Re: built in chain tensioners damage the axle?
« Reply #10 on: March 01, 2020, 01:52:34 AM »
I can't confirm nor deny this since I don't have any frames that use a similar dropout design with 3/8" slots but 3/8" copper pipe exists as well which should be able to be used with 3/8"/10mm axles. I don't see why it wouldn't work bolts for female axles as well. Only issue I can imagine with female axle bolts is the shim wanting to shift around since the threads of the bolt will be spinning while tightening things down unlike a male axle which generally stays stationary when tightening down the nuts. 3/8" diameter pipe scraps though might not be so ready be laying around like the leftover 1/2" pipe pieces I had from doing a bunch of plumbing work in my house. 3/8" is more commonly used with gas applications but at least in the US a 2" section of it from a home improvement store will be about the same cost in material as the adapter washers that were used in the video.

Offline ollie

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Re: built in chain tensioners damage the axle?
« Reply #11 on: March 01, 2020, 09:18:19 AM »
Why would you ever need the part of your axle which is in the dropout to be threaded?

I had a Haro hub once which was modified from 14mm to 10mm and completely missing the thread inside the dropout, even a bit more inside the peg, absolutely no problem to tighten it up or else.

Offline jerky

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Re: built in chain tensioners damage the axle?
« Reply #12 on: March 01, 2020, 10:37:04 AM »

Quote
Why would you ever need the part of your axle which is in the dropout to be threaded?

It not a matter of you need the bolt to be fully thread threaded but all bolts that came with the female hubs I currently have don't have any substantial unthreaded shoulder on them. I agree having a longer shoulder on the bolt is much better design though(IIRC those Haro hubs were called mega hubs). Over the winter I've been building a flatland bike for my kids to mess around on when the weather gets nice again. The Federal v1 freecoaster I'm using for their rig has been given a sex change using a KHE greyhound female axle. The bolts I used were odyssey branded and the unthreaded shoulder section is maybe 2mm at the most (see attached photo), definitely not enough to reach though the peg let alone the peg and dropout. The Profile/Madera chromo 3/8-16 17mm hex bolts have a minimal shoulder as well. So given many mfg provided bolts are almost fully thread, that's why I mentioned the same hack could be used with a female hub too.