let me first say that I don't have a lot of experience on this topic so my questions will basically be two-fold: First ask if my observations and assumptions about the gear I have is correct and then what I need to do with this information.

I do have two wheels that I want to use with a frame. The wheels are as far as I can tell WTB Serra i23 TSC 2.0 wheels. I haven't found anything written on the hub so I guess these are WTB Serra hubs. I measured the front wheel hub to have an inner diameter of 12mm and and length of 100mm. The rear wheel I measured to be roughly 12x142. However, the frame is, I think, designed for quick release wheels and not thru axles and I measured on the fork an diameter of the dropout (is that the right term?) of 10mm and the inner distance of the dropouts to be 101mm. So I guess, this is a 9x100 QR fork? In particular, I was confused that I measured 10mm instead of the apparently common 9mm but I guess that happens? For the rear I measured again a diameter of 10mm for the dropouts and roughly an inner distance of 138mm between the dropouts. So this should be 10x135 QR, right? Also I have added some pictures that show the end cap of the rear wheel and a picture of my frame to confirm what I said is true.

Now, if all of the above are true, I cannot fit the wheels into the frame and need to make some adjustments. For the front wheel I have seen some adapters (e.g. an 12x100 to 9x100 QR adapter made by SON) and then using a QR skewer for 9x100 this should work? For the rear wheel I need to decrease the width of the hub. I read that this is usually only possible if the manufacturer makes end caps that can be changed. I saw on the WTB web page these drawings (WTB Serra hubs) and this replacement parts page (WTB replacement parts) that can be ordered so I am optimistic that this should be possible in theory. Now, my main question is what I will need to order and install. First, I thought that I would only need to replace the end caps so that I can just order the desired 10x135 QR Serra end caps that are mentioned on the replacement parts page. But when looking at the drawings (where a lot is displayed that I don't understand), it looks like e.g. the 10x135 QR Serra hub uses differently sized bearings compared to the 12x142 hun meaning that this (and maybe more) needs to be changed as well. What do you think?

Finally, I do have another logistical problem that I am not sure if you can help me but I do live in Europe so I cannot just order from the WTB page. There are some European distributors listed but when I click on the one for my country, this distributor seems to be only for B2B customers. Do you have any ideas how I could get the needed parts? Should I just go to a local bike shop and ask whether they can order parts from WTB?

Thanks a lot!

Edit: Now, I have also noticed that in the drawings of the hubs it is stated that the Serra QR x 135 hub is using 32 spokes whereas the 12x142 is using 28 spokes. And indeed I have counted the spokes and there 28 on my rear wheel. Is this the final blow to my plans? What should I do?

rear hub rear frame droupout

4 Answers 4


The inner distance between dropouts is the same for 12x142 through axle and 10x135 Quick release. Through axles require a 3.5mm inset in the frames to position the axle, but the position of the cassette and (disc) brake is equivalent for the two formats.

About the question on the end-caps, it depends on the hub: not all hubs are designed to have interchangeable end-caps. If your hub is designed to have have interchangeable end-caps, your understanding that changing the end caps for the hub should be sufficient is correct, there should be no need to replace the bearings. If not, a hub replacement is the only way to go (that might be more expensive than buying a new wheelset, because of labour).

Now the question is to see what hub you have: if the manufacturer doesn't commit for a given hub in the spec sheet (or no clear reference is written on the part), it can also be a no-name part. It looks like WTB only have two hubs families: Frequency and Frequency competition, with interchangeable parts. If it's the case with your wheels and that they are compatible with the current range, it should be OK. You can maybe contact WTB directly to have confirmation.

  • "The inner distance between dropouts is the same for 12x142 through axle and 10x135 Quick release." implies that TA hubs aren't described by their OLD - but only 3.5mm per side difference doesn't seem enough to make it the full axle length. So I wonder what the 142mm actually refers to
    – Chris H
    Commented Apr 19, 2023 at 13:33
  • 4
    @ChrisH as I understand it, 142mm is indeed the distance between inside part of the dropouts (with a 3.5mm inset), but the position of the brakes & cassettes is the same as a QR 135mm. In other words, if you take a hub with interchangeable cap-ends, QR135 and TA142 are equivalent, while boost hubs (141mm OLD) have the brakes and cassettes further from the center.
    – Rеnаud
    Commented Apr 19, 2023 at 16:01
  • First of all, thanks for your answer. Regarding the specific hub that is installed: I linked this document for WTB Serra hubs (WTB Serra hubs). On the first page, it states how to distinguish between Serra and Speedterra/Proterra (which are called Frequency/ Frequency Competition now). The disc mount in the document for Serra hub does look like the one I have but of course you are right, that without any written on them they could be anything.
    – tor
    Commented Apr 19, 2023 at 16:07
  • 1
    Furthermore, if they are Serra hubs, the end caps are interchangeable as it is explained on page 7 of this how to do this for Serra rear wheel hubs. But I even if my hub is a WTB Serra hub, I am confused whether this is possible since as I said in the edit the 12x142 and 10x135 specifications even have a different amount of spokes. But I guess, as you said, I can write an email to WTB.
    – tor
    Commented Apr 19, 2023 at 16:14
  • @tor I already tried to contact some component manufacturers directly (but not WTB) and they have been quite reactive. I guess that having an online shop is good incentive for them to answer customers inquiries.
    – Rеnаud
    Commented Apr 19, 2023 at 20:27

No, for two reasons:

  1. Your frame looks to be made from aluminium, and that cannot be cold-set to adjust the OLD. If it were a steel frame then maybe, but aluminium will take damage.

  2. Your wheels are designed for a through axle, whereas your frame is only designed for quick release axles. It may be possible to buy end caps for these hubs that provide the right interface for a QR, but the wheels will still have an OLD wider than the frame.

Your best option is to buy a pair of QR wheels for your frame, or buy a through-axle frame that will fit your wheels.

Consider on-selling the parts you don't want to help fund the parts you do need. If the bank-account permits, do both and end up with a pair of bikes, one with QRs and one with Through-axles.

  • 1
    Okay, thank you. Regarding your first point: You are talking about that it is not possible to just use 142mm on a smaller aluminium frame, right? Since, I also asked about the issue with 138mm actually measured vs 135mm being probably the intended width by the manufacturer. I thought it might be possible to convert the wheels since I saw some things implying this (e.g. see third paragraph of bicycles.stackexchange.com/a/71673 ). But I guess in my particular case with the WTB parts, this does not seem to be easily achievable, is what you are saying?
    – tor
    Commented Apr 19, 2023 at 11:10
  • 2
    @Criggie, on your second point: I understood 142mmTA and 135mm QR have the same OLD, there's a 3.5mm inset in the frame for TA. Or is there something else?
    – Rеnаud
    Commented Apr 19, 2023 at 12:34

This adds some minor details to the other answers.

When you measured your hubs, you said that the "inner diameter" is about 12mm. That's the diameter of the thru axle. The 9mm in the names for the QR hub/dropout dimensions refers to, I think, the diameter of the hole that the skewer goes through.

Many hubs are designed so that you can replace just the endcaps to adapt the hub to 9x100 or 9x135mm QRs, or even to 15mm thru axles in front (more common for MTBs than drop bar bikes). If you knew who the original hub manufacturer was, you could also approach them or see if a local shop's distributors have access to them. DT Swiss are a common spec that does this, but those tend to be on higher end wheels, but I have a feeling these wheels are likely to be Taiwanese manufacturers like Novatec, Bitex, or someone else. The problem is that you don't know who it is. The WTB folks might tell you, but I would not bet on this.

You could ask your LBS if their distributors have access to WTB's products and spare parts. For example, Quality Bicycle Parts in the US carries just about everything, and just about every store has a QBP account. Naturally, this wouldn't help if we were trying to get spares for some niche European brand (e.g. Tune, a German manufacturer of super weight weenie parts). I glanced at WTB's international distributor page. I'm not sure where in Europe you are, but the listings don't seem helpful, and you're right that the German distributor doesn't list the dealers it works with.

You could try to contact a US retail store. Some of them will be willing to ship stuff internationally at added expense. Be aware that due to the additional paperwork required, it is more time for them, and not everyone may be willing to do this. It's possible the store would be able to help you confirm the model of wheel you have, although doing this remotely is not always easy.

If you go to an LBS armed with the name of the distributor in your country, they might be willing to open an account with that distributor if they don't already have one. It's also possible that staff will know which LBSes work with that distributor.

Last, it seems possible that if you called the distributor, they might deign to tell you which retailers they have accounts with. It struck me as odd that the German distributor didn't have a listing and map of stores. After all, WTB itself has a map of US retailers, and there are a lot of bike stores in the US that have access to WTB parts. QBP does not have a similar map, but as I said, essentially every US LBS is going to have a QBP account.

  • The 9 in 9x100 and 10 in 10x135 are axle diameters in millimeters. The QR skewer is much thinner.
    – ojs
    Commented Apr 20, 2023 at 21:25

Contact WTB. They can do 2 things for you:

  1. Verify it is a WTB hub
  2. Confirm whether their hubs are convertible between qr and thru axle (and the part numbers involved)

I honestly didn't know WTB makes hubs until this question. Their rims get used frequently by OEMs with various hubs attached. With no branding it's difficult to say.

On the WTB site I see you can order end caps and a qr for a the hub you mention, but all manufacturers are different and there may be something different about the shell from qr version to thru-axle version or some other aspect that makes it not a simple matter of changing end caps and throwing in the qr skewer.

Some brands make it more obvious, e.g. Nukeproof (rebranded formula or novatec, I think, they don't make their own hubs) have kits available for conversion readily available on Wiggle/CR. If they were DT hubs nearly any LBS would know if they can be converted and would likely have parts on hand.

A note on sizing as it's a bit confusing between QR and TA (I always have to look it up):

  • 142mm x 12mm thru axle spacing = 135mm QR
  • 148mm x 12mm (aka Boost) = 141mm QR (aka QR Boost)

The difference in size is due to 3.5mm spacers on either side of the hub for the thru axle (not used for QR).

I think for front wheels you can get a generic adapter, the rear hub isn't generic due to the freehub.

  • Thank you for your answer. What do you mean by "The difference in size is due to 3.5mm spacers on either side of the hub for the thru axle (not used for QR)."? The inner width between the frames still needs to be 142mm for 12x142 hubs and 135mm for 10x135 QR hubs, right? But since 12x142 basically adds only 3.5 mm spacers on the outside the distance from to the cassette to the wheel (and thus the chain) stays the same? Thus, one could just theoretically grind of 3.5mm on each side to get fitting hub for 135mm frames? Or how does this have an effect practically?
    – tor
    Commented Apr 22, 2023 at 19:17
  • The hub body is the same (flanges etc) are the same between boost (148mm) thru axle and a 141 qr boost axle (rarely used now, but the Norco fluid fs had them until 2029 iirc). They are both boost standard (same cassette offset, same hub width etc) the difference is the end caps. I guess theoretically one could maybe cut down the end caps and use a thru axle adapter like a front wheel (if you could find the right size) but I'm not sure they exist as most popular hubs you'd just swap end caps from thru axle ones to QR. Look at dt swiss 350 for an example.
    – shox
    Commented Apr 22, 2023 at 20:48

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