IceTee2

I am looking at several on-line sites for a wheelset for the 2005 Trek 520 that I am building as a winter project (frame and fork only). I'm a little confused over some of the nomenclature used. I'm presuming the "QR" is reference to quick release skewers and "T?" is thru-axle. The QR versions state "10 mm x 100 mm" for the front wheel and "12 mm x 135 mm" for the rear, both listed as "QR". Does the 10 and 12 mm dimensions refer to the axle diameter. I never thought that the from axle and rear axle was different diameter. Are the skewers also different diameter?.BTW, the Trek frame is 135 mm in the rear and was a 9 speed and will be again on this rebuild. Thanks in advance for any clarification....Jerry

Bill Kapaun

For that era bike, I'd expect a 9x100mm front and a 10X130 or 135mm rear.

canopus 

Axles are different in diameters. QR's are same diameter, different lengths.

IceTee2

I think this is going to get problematic fast. I just measured the rear dropout on my 2005 520 frame AND my 1995 520 bike/frame and they are both identical....9+ mm. The rear axle also measures 9 mm (actually around 9.6 mm). Are 10 mm axles actually <10 mm in diameter? And I thought the wheels would be the most straight-forward part of this build.

canopus 

Why are you so worried about axle diameter? The axle fits the hub... What hubs are you using?
It is simple really, as it isn't thru axle setup, it isn't an IGH, it doesn't have discs... Measure the frame, order old fashioned hub to fit.

Andrew R Stewart 

Since the axle should fit snug against the upper surface of the dropout slot (be it a horizontal or vertical slot) the axle diameter doesn't matter, as long as the axle does fit the slot.

BTW there's a huge difference between a 9mm and a 9,6mm (likely 9.5) axle diameter. If this is in doubt just ask a 9mm cone

Where does the "T" reference come into play? It's mentioned once and not again. It's nice to know from where does references come from if not addressed later in the post.

Front and rear axles have had different diameters for about 100 years in most threaded axle designs. Nothing new or odd. This data is available from any number of sources like Sutherland's or Sheldon Brown sites.

Last bit on axle diameter. The threading spec (which will list a nominal diameter) is not the same as an actual measurement. Most all threads do not have a sharp "V" shape for their crests, but a flat or rounded tip so a measurement will read out slightly less than the spec listing. Andy

IceTee2

Andrew, The reference to the "T" has a typo, it should be "TA" and I'm pretty sure that denotes a thru-axle hub. I just went to the garage and 'carefully' measured the axles on the 1995 Trek 520. These wheels it the 2005 perfectly. The front axles threads measure 8.83 and the rear axle threads measure 9.84. Both are the average of three measurements since it's tough to read the calipers with the available light in my garage. I think I'm safe assuming the threaded portion of the axles is slightly smaller than any "unthreaded" portion of the axles. I think I'm safe with 9 mm and 10 mm front and rear respectively.

Canopus, I bought the 2005 frame and fork ONLY. Everything else was used by the original owner to outfit a 'screw=together' frame for his annual trip to Europe when the airline rules changed regarding 'bikes in a box'. It's just a learning experience for me to put together a complete bike...simple as that.

Thanks for the input....Jerry

HillRider

For quick release hubs, nominally 9mm front and 10mm rear axles have been standard for decades so it's certain both of your 520's require them.

Thru axle hubs are a relatively new development that first appeared on mountain bikes with disc brakes and have since made it to gravel, touring and some road bikes, again mostly with disc brakes. The typical thru axle specs for touring and gravel bikes are 12x100 front and 12x142 rear. The thru axles themselves nearly always come with the frame and fork, not the hubs.

Enjoy your new build and good luck finding all of the components you need.

Andrew R Stewart 

Most all current steel axles use rolled threads. These threads are made by deforming the axle's surface with sharp disks (like a pipe cutter) that both push into and displace upwards the surface of the axle. The tops of the threads end up slightly higher than the starting axle surface was. Ot in other words slightly bigger in diameter then the axle's smooth center portion. Rolled threads are very fast to form, can be done in a high production factory with fairly low cost tooling and are actually stronger then die cut threads are. Still the rolled threads need to end up at some % of "perfect" thread form. Rolling is less precise but far good enough, and due to the common stripping potential, better then die cut ones. Andy

DaveSSS 

Even rolled threads have to meet the same crest diameter limitation as cut threads, or they won't mate with a tapped nut.

IceTee2

I probably 'jumped the gun' on this thread. I susally research EVERYTHING several time before I do anything. It looks like I took a shortcut on axle diameters but the responses have provided a lot of good info that I probably wouldn't have come across on my own. Good answers are tough to come by when you don't even know the question. Thanks to all for your responses...and encouragement.

70sSanO

My only advice for whatever wheels you get, especially if they are cheaper; if they are cup/cone, open them up, clean, re-grease and adjust.

I would go as far as new Grade 25 ball bearings in cheap wheels, even new. You only have one shot at this.

John

LV2TNDM

I always replace OEM bearings with grade 25. It's a pretty big jump from 300 to 25, so worth it if you're going to all the trouble of overhauling a hub and want it to last. Cheap insurance.

IceTee2

I recently cleaned and re-greased the hubs on my "other" winter project, a 1995 Trek 520. (I think I have an affinity for the 520.) It has Deore LX hubs with almost no mileage on the bike....<500. The races looked fine after cleaning so I simply re-packed using marine grease. While it's still in pieces for cleaning and cable and brake pad replacement should I replace those wheel bearings? I don't find a reference to bearing quality on the Shimano website...Tech section.

canopus 

Clean, pack, put 'em back together. At less than 500 I wouldn't bother with replacing the bearings. Just inspection. Stop overthinking this stuff. The base design is amazingly strong and will last a long time if maintained. All this other stuff is designed to solve a problem you don't have so you need to let all of it go and go ride.