7mm vs. 8mm Axles
I am about to build some new quad (speed) skates for the first time in over twenty-five years. Whilst shopping for gear, I couldn't help but notice that nearly all of the quad plates come standard with 8mm partially threaded axles now.
Back when I was racing (from the late 1970's through the mid 1990's), all of the good quads had 7mm axles and bearings. The axles were threaded all the way to the trucks and were secured with stub cones that also focused the contact onto the center of the bearings.
Did the standard change for any particular reason? Does it have anything to do with the fact that there is no longer such a thing as a quad speed meet?
Does the lack of stub cones on the 8mm axles cause the bearing shield to scrape the truck surface during side-loading?
I realize that an 8mm axle might be slightly more durable than a 7mm axle, but if both size bearings have the same outer diameter, wouldn't the 8mm bearing require the use of smaller balls, therefore reducing load capacity and impact resistance, while increasing friction slightly?
I am tempted to just go with 7mm axles out of familiarity and because I very rarely ever bent axles, even outdoors. Still, I am curious, and I wouldn't want to miss out on an improvement if there is one available.
Any suggestions, Doc?
Thanks for taking the time.
Cheers.
This is my signature.
Comments
Did the standard change for any particular reason?
8mm seems more "American"/standard. E.g. skateboarders roll 8mm bearings. So I guess availability is also much higher (at least where I am). If you want 7mm lack of local availability shouldn't stop you.
[So far,] I've only seen Rolline with the 7mm axles. I am fairly new to skating [compared to some of the OGs here] so think of my comment as a starting point. I can't think of a reason to have 8mm over 7mm.
7MM Axels are heat treated....
8mm isnt just another way manufactures cheap out
Altamuras
I am about to build some new quad (speed) skates for the first time in over twenty-five years. Whilst shopping for gear, I couldn't help but notice that nearly all of the quad plates come standard with 8mm partially threaded axles now.
One can thank roller derby for the current trend in 8mm axles. Remember, manufacturers are in this to make money. I have some derby sk8rs on 7mm axles but the majority are on 8mm.
Back when I was racing (from the late 1970's through the mid 1990's), all of the good quads had 7mm axles and bearings. The axles were threaded all the way to the trucks and were secured with stub cones that also focused the contact onto the center of the bearings. Did the standard change for any particular reason? Does it have anything to do with the fact that there is no longer such a thing as a quad speed meet?
Yes, many of them were, but not all of them. BTW, the stub cones were a left over from loose balls. They were just cut shorter. The "standard" changed because the previously mentioned loose balls were phased out. That left the manufacturers with 2 options for easily obtainable bearings. 627 (aka 37) or 608 (AKA 38). The loose ball axles were too big for the 627s and too small for the 608s. 627 axles are typically ground to size and are much more expensive to make than the "8mm" axles which are typically made from 5/16" steel rod which can be obtained in coils hundreds of feet long and quickly turned into axles. (Remember, axles are essentially studs.) These have a less than optimum but generally acceptable fit on the 608 bearings. Also very inexpensive to make unless you look @ a Sure Grip A1 axle which is probably the best axle of that type made. Longer to accommodate the old .4" bearing spacing, and heat treated.
The majority of American 7mm (9/32") axles are ground to diameter so more expensive to make. Most of these are heat treated but not all.
BTW there are 2 different National speed meets in the US, both feature quads. Also note, during the Quad speed drought in the 90s and 2000s the inlines all ran 8mm axles...and still do.
Does the lack of stub cones on the 8mm axles cause the bearing shield to scrape the truck surface during side-loading?
Depends on the precision of the truck manufacturing. A lot of vintage speed plates did not have fully threaded axles and stub cones. The American Whip and Italian WIP (w/o flip axles) came that way as 2 examples. Speaking of flip axles, I have never seen them w/ stub cones.
I realize that an 8mm axle might be slightly more durable than a 7mm axle, but if both size bearings have the same outer diameter, wouldn't the 8mm bearing require the use of smaller balls, therefore reducing load capacity and impact resistance, while increasing friction slightly?
Nope. The only difference is the size of the hole in the inner race.
I am tempted to just go with 7mm axles out of familiarity and because I very rarely ever bent axles, even outdoors.
The grossly overrated Pro Line has lots of bent axles...well trucks actually, due to the pilot hole in the middle of the axle. The truck bends but when I punch out the axle (Yeah I know the axle is not replaceable, but I do it any way.) I find the axle is straight. I do not buy them used any more without expecting to find one or 2 bent "axles".
Still, I am curious, and I wouldn't want to miss out on an improvement if there is one available.
No difference in performance in the of the bearing since the only difference in the bearing is the size of the bore in the inner race. The difference is in availability. Blow up a 627 and a lot of rinks here don't carry them much less anywhere else. If the rink does not have 608s one can run to the local mart and find spare sk8 board bearings.
Any suggestions, Doc?
Look @ Bont's 8mm trucks. The axle are true 8mm.
Thanks for taking the time.
Most welcome !!
Boen make 7mm trucks & quick release & are available. It's possible the trucks will fit other brands as i 've seen it done on youtube. The only issue is whether boen will reply. I add that as i emailed them back in april to buy some skates however they didn't bother getting back which i didn't appreciate & decided to steer clear. There are no boen trucks on amazon or ebay. I was looking yesterday. Yes 8mm sux. Nylocks even more so. I so miss QR edit: ffs now i can't spell it seems lol by should be buy grrrrr
Faking it till i make it
Doc, and scorp,
Thanks for the information.
I had already ordered some Sure Grip Avengers with 7mm axles by the time I saw your reply though. They are "out for delivery" today. Hopefully, they will be a nice, snug fit to the 7mm bearings. I'm pretty excited to get back onto a set of quads!
Happy New Year.
Cheers!
This is my signature.
Oh, Doc,
You said there are 2 different National speed meets in the US that feature quads.
I searched the USA/RS site and could find only inline speed results for 2019. https://usarollersports.wixsite.com/nationals/copy-of-event-results
It looks as if the last quad national they held was 2018. https://www.teamusa.org/USA-Roller-Sports/Results/2018/July/10/2018-USA-Speed-Skating-National-Championships---Current-Results
Who else was operating a quad national?
Again, Thanks for your time.
This is my signature.