Russ Roth

My front wheel won't fit the new fork, wheel is only 2 years old and is a Shimano 8000 series XT non-boost front hub with 15mm thru axle I built for my gravel bike. The old bike just let me use a shim to fit but it was clearly designed to use 15mm axles. The new fork is clearly not designed to fit 15mm as the axle won't fit in the drop out at all.
I haven't heard of anything but is there a 12mm thru-axle that will work or is the hub shell the same as say an ultegra and I could source a 12mm ultegra axle and cones and make this work?

I'd rather not rebuild the wheel with a road hub though I might if that's the solution, just hate to waste the time and money if there's an easier solution.

elcruxio

I'll preface this by saying that 12mm road front thru axles are one of the most stupid things I've ever seen in the cycling industry. This coming from someone who's slowly shifting all my bikes to thru axles. 15mm should have been enough. There really isn't any sort of weight advantage in using the small 12mm thru axle and on top of that, durable 12mm front hubs are extremely difficult to find. The only options really are using hubs which have swappable end cones. Mainly these tend to be Hope or Novatec hubs. Actual 12mm front hubs tend to be road specific and thus light, not as well sealed and use really small bearings, which isn't great for a front hub. Smaller hub flanges and all that.

But it depends which hub it actually is. If it's a HB-M8010 you're out of luck. But if it is in fact a HB-M8110 you might have a shot. Because both the 15x100mm HB-M8110 and the 12x100mm HB-R7070 or the HB-RS470 use the same amount of 5/32 bearings. 15 balls on the left and 17 balls on the right.
This in turn means that to fit the same amount of bearings the cups and cones kinda have to be the same size.
You likely won't be able to make the seals work great so in the end you might end up with a largely unsealed hub.

Check my research before you buy anything. And it bears reminding that mixing and matching axles in Shimano hubs probably isn't a great idea.

GrainBrain

I helped my friend who was in this same situation. I ended up turning down his end caps on a lathe, and he used a 12mm to 15mm sleeve he bought online. I can't remember what the hub brand was though.

Russ Roth

That's the info I was hoping/not hoping for. It is an m8010, I'd been hoping the 7070 would share parts since a shared hubshell would seem reasonable for 105/slx and XT/Ultegra but so be it.
It seems there has been a real push to separate road and MTB components more as the gravel market has surged which is really annoying. I liked when MTB rear derailleurs worked with road shifters and there's no reason they shouldn't be able to other then Sram and Shimano want to keep things more specialized and annoying and hubs are only one more example.

Looks like this is the option, I'd been looking at the rear hub for some reason and it couldn't be turned but the front does actually have aluminum ends that will be able to be turned down.

katsup

Adapters exist, but I have no personal experience using one.

https://bikerumor.com/2018/10/31/rev...oying-problem/

veganbikes

The rear axles are all 12mm! I am not saying that we needed a new front axle or anything or totally disagreeing but if we are saying 12mm is bad then why not at the rear? I would love to see everything be the same it would make things easier for sure but I think at least for a while we will have 4 main front axles 12 and 15, boost and not. (yes I know 20mm and 20mm boost and all that weirdo stuff but that is mostly on DH)

Honestly yes we would all love to have that one single standard to make everything easier and yada yada but we all want that and it is all different. Let's just hope we can stay with just those 4 at the front and be ok!

elcruxio

I suppose the MTB front end needs to be a bit larger because of suspension forks. The rear triangle doesn't flex all that much so there's less benefit of a beefy axle there.

The reason why I'm fuming about the 12mm road front axle is because Surly in their infinite wisdom decided to put a 12mm front axle on their new Disc Trucker, which is a touring bike. Ie. it would be nice if the front hub was beefy, well sealed and used larger bearings.
Now of course usually it would be possible to just get a hub with swappable end caps and call it a day, but currently due to Covid and all that supply is non existent. So no 36h Hope Pro 4 front hub for me. Luckily I managed to find a Novatec XD641 which has swappable end caps AND uses massive 6904 bearings. Unfortunately it's only 32h and the flanges are pretty light construction. Buuut I've never seen or heard of a broken front hub on a touring bike so fingers crossed

HillRider

Surly also uses 12mm thru axles on their Midnight Special gravel/road bikes. I just built one up and the best reasonably priced wheel set I found was Shimano's GRX WH-RX570. These take 12mm thru-axles, centerlock rotor mounts and are wide enough to fit 700-42 tires. They have cup-and-cone hub bearings taking 14x 5/32" balls on each side in front and 16x5/32" balls drive side and 13x3/16" balls nds. That should be plenty durable and they are well sealed.

I also think 12mm thru axles are plenty big for road, touring and gravel use. After all we got away with 9mm front axles for many decades. The 15mm thru axle may be a benefit to stiffen up a suspension fork but is unneeded for road forks.

elcruxio

5/32" balls are absolutely tiny. Perhaps those are fine for road use but for touring I don't think they're nearly enough. Front may not get a high constant load but when braking the front hub will carry the complete weight of the bicycle+rider+gear. Combine that with rough roads and I'm guessing the 5/32 bearings start to near their static load ratings.

The novatec hub I bought has 6904 cartridge bearings inside. Those contain balls which are larger than 1/4" so plenty durable.

It's also not really about the axle size or what "suffices". 9mm was fine (well, quick release works, just not as well as thru axle). It's about the silliness of having several different incompatible axle diameters when one or at the most two would be more than enough. 20mm for downhill and 15mm for everything else.

HillRider

First 5/32" balls aren't that tiny, they are 83% the diameter of the more common 3/16" balls in most front hubs, and Shimano uses significantly more of them per race. Campy has used 5/32" balls in both their front and rear hubs for many years and their durability is legendary.

I agree that there are two many axle "standards" but just settling on 15mm wouldn't really simplify anything enough to matter. There are a legion of axle lengths, thread pitches, thread lengths and clamping methods and until those are standardize the confusion and supply issues will continue. Look at the "Robert Axle Project" web site to see how chaotic the situation really is. They make about 300 different thru axle configurations and the majority differ in threading pitch, threading length and overall length.

rosefarts

Novatec 791 and 792 are pretty dang light and have swappable caps. No tools required. I have a front, kinda wish it was the set.

I have a Stan's 3.30RD rear hub and while I was able to swap it from QR to TA, I needed a new axle, caps, and to pull the bearings and press them back in. Not sure if all that is needed for the front hubs.

Russ Roth

That was my view when I built the first gravel touring bike, mtb hubs are sturdier and went with XT which worked well, now I find that what should be the more rugged frame designed to take MTB tires won't take a mtb hub, bad planning there.

Just found out that Chris King has a 12mm classic hub axle which would let me re-purpose an old set of hubs but that axle seems to be as rare as anything.

veganbikes

Yeah a touring bike with thru-axles is a bit odd in some senses but the benefits of thru-axles is quite nice especially with disc brakes and to be fair probably most of the riding that a lot of Surlys will see will be near "civilization" so more chance of bike shops and plus with easy global shipments (in normal non-covid times) having a thru-axle is less of an issue.Yes QRs are certainly the easiest to find still but I don't think TAs are as bad these days.

The Novatec hubs seem to always get decent enough reviews would I choose them on my build, probably not but for stock build as they are doing is probably not terrible. It is pretty doubtful you will have issues with a 36h hub on a disc trucker

Pridedog

[QUOTE=katsup;21910509]Adapters exist, but I have no personal experience using

I used an adapter to solve this problem when I had to switch to a 15mm front wheel from original 12mm. Works like a charm and no fuss.

Pop N Wood

[QUOTE=Pridedog;22059644]I was going to say, putting a 15 mm through axle wheel onto a fork threaded for a 12 mm one is the easy path. Just use a $15 adaptor

https://www.amazon.com/Dymoece-Bicyc...NsaWNrPXRydWU=

Trying to put a 12 mm wheel on a 15 mm fork is the one that can't be done.

unterhausen

It sounds like the OP had a fork that was a bit small and a hub that is very close to the max size for the 12mm TA standard. Lots of 15mm hubs will fit in a 12mm fork, then you just need an axle spacer, as linked above. I think some forks are closer to the standard than others.

I'm going to face this problem soon with a dynohub. Hope it works out.

I was pretty annoyed when the 12mm front hub standard was announced. It really does seem pretty pointless. Now they announced road boost. Next will be road 15mm boost, which is going to be incompatible with mtb somehow. I'm hoping companies will ignore road boost, but the possibility that sanity will prevail seems remote.

joejack951

I beg to differ: https://www.ebay.com/str/jjpellc

Shameless plug for my Ebay store full of kits to do what 'can't be done' :-)

joejack951

Which hub and fork? I'm nearly certain I can help.

joejack951

12mm hub end caps are almost universally 19mm (I say 'almost' only because I can never be too certain in this industry!). 15mm hub end caps come in a few different flavors, most commonly 19mm and 21mm (but also 25mm). Many 15mm forks intended for road/gravel use are designed around 19mm end caps and thus the hub alignment 'shoulder' only has enough clearance for that size of end cap. A 21mm end cap will interfere by ~1mm.

If you have a 'MTB' 15mm fork, chances are it is designed to clear 21mm diameter end caps, or more. There you only have the minor issue of those shoulder being relatively useless for aligning the hub during installation.

msr_78

Hi, bit late but in case you see this: I have a couple of 15mm hubs that have no 12mm end caps available (Sun Ringle) and I was thinking going the lathe route for at least one set of endcaps - not having a lathe and not wanting to spend a whole bunch on one, I've seen small ones for $50 on amazon - do you, by any chance know if a 200W motor lathe would be enough to shave off what's needed? What type of "knife"/blade did you use?

Many thanks

msr_78

Sorry, directed to GrainBrain

Hi, bit late but in case you see this: I have a couple of 15mm hubs that have no 12mm end caps available (Sun Ringle) and I was thinking going the lathe route for at least one set of endcaps - not having a lathe and not wanting to spend a whole bunch on one, I've seen small ones for $50 on amazon - do you, by any chance know if a 200W motor lathe would be enough to shave off what's needed? What type of "knife"/blade did you use?

Many thanks

GrainBrain

I'm not sure what you mean by "200W motor lathe", like one of those small jewelry lathes? I'd think it would be fine. I used a cutting tool with a squared end and just plunged in the length need to fit into the forks dropouts. I can't remember any exact dimensions now. I feel like I needed to turn down the outside diameter something like 1.5mm, at a length of 3mm? Those numbers I just pulled out of thin air.

Have you used a tool like this for turning metal?

Have you used any kind of measurement tools or have access to them?

msr_78

Exactly, that's the kind I mean - they show it as being used to carve small pieces of wood, etc...

Never used a lathe before, but I have used Dremel extensively (and done extensive damage, but live and learn) and I would consider myself handy enough. I'm no mechanical engineer, that's for sure. I was thinking of using cork, or soft wood as stops to secure the end cap on the lathe, open to suggestions.

I measured a set of 15mm end caps and 12mm and I think your numbers are approximately correct, it was 21 vs 19.5, give or take - measured with electronic calipers - the length though was considerably less, about 2mm max I'd say (SunRingle vs Novatec end caps) - would you recommend any other measuring tool?

Thanks!

Russ Roth

My lathe is an antique Delta that was meant for wood and metal turning, outside of basic brass and aluminum I wouldn't want to really try turning metal with it but I'm sure it was more cutting edge when it was made 90ish years ago. But I was able to set it between a dead center at the head and a live center at the tail which, with a little bit of pressure, allowed me to shave it down with a fairly sharp wood tool. I didn't need to change length so I grabbed a wrench as wide as what the outside of the spindle needed to be, think it was 17mm but would have to remeasure to state that. Just turned till the wrench just fit over the axle and then used some 2000 grit paper to polish the cut away area. Came out looking good and for the xt left the flats I needed still there for hub bearing adjustment.

msr_78

Thanks! I was actually thinking of using some cork or soft wood to wedge the end cap snug as the small lathes I'm looking at don't seem to have the range to clamp either end securely. I think I'm going to give it a go - I'll practice with some wood first not to mess it up too much when it comes to the real thing

If I don't post back then assume I've ended with a 15mm endcap embedded in my forehead