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In the links I gave below, the website is in French but you can change the language.

Following this thread I bought new bike components to build my own bike. In particular I bought Surly Steamroller frame and a this Surly fork. I have a QR system to attach this wheel because I wanted to install a disk brake system: disc, brakes.

When I am braking, the front wheel is moving on the left of the fork. I tried to change the QR attach, tighten it very hard but same problem. Is it possible I have an incompatibility issue especially between the fork and the frame?

diska

diskb

edit: I followed the remarks from here and I tightened the QR even more but same effect. Could it be my fork that is moving and not my wheel? I notice that the spacers on top of my headset may be too long (4.5 cm of spacer) and could cause the fork to move, is it relevant? I think I will shorten my fork removing spacers.

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  • Offtopic, but the front rack attachment is a ticking time bomb. It could work if the rack is there only for show, but for any significant loads it should be attached directly to the dropout without the bolt as cantilever
    – ojs
    Mar 31, 2021 at 9:47
  • @ojs : thanks for your remark. Even if I attached the rack in the middle of the fork with this attachment ? rpidejr.hopto.org/f/82aaf37a8e8a498d80c1
    – Smilia
    Mar 31, 2021 at 11:27
  • If the middle of fork is bolted directly to fork, it should be OK. I see that the rack is stabilized by connection to fork crown, so the attachment at dropout isn't really needed.
    – ojs
    Mar 31, 2021 at 11:30
  • Related: bicycles.stackexchange.com/questions/64216/…
    – Ralf
    Mar 31, 2021 at 11:48

2 Answers 2

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The front wheel (of wheel set you linked to) has a 12x100 mm front axle (road thru-axle) but comes with an adaptor for 9x100 quick release axle, and the fork is made for 9x100 quick release axles. Did you install the adaptor kit correctly on the front wheel hub?

If you grab the front wheel by the tire close to the top of the fork and push/pull the wheel from side to side, do you notice the wheel moving at the quick release?

If it moves, there must be something wrong with how the quick release holds the wheel to the fork. Do the end of the axle of the wheel hub protrude out of the fork so the quick release can't make correct contact with the fork?

Minor notice:
The brake disc and brake caliper is not 100% compatible. The RT70 disk is ment for calipers using narrower brake pads, and the MT 200 uses wider brake pads. This means the brake pads is slightly larger than the brake area of the discs, but I'm not sure what the actual consequences will be in this case. Shimano has a document that state compatibility of their products:
https://productinfo.shimano.com/download/pdf/com/2.6/en

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    Using the wrong pads will result in shorter pad life and possibly a mild brake failure in the event that after significant wear, the unworn sections bottom out against each other before the center section contacts the rotor.
    – MaplePanda
    Mar 31, 2021 at 18:38
  • @MaplePanda Good point. Another issue with larger brake pads on narrow discs is that the brake pad might hit the "spokes" of the rotor, causing damage to the pads or possibly rought/jerky brake action?
    – MagnusK
    Mar 31, 2021 at 20:39
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You noticed that quick releases are unable to hold the wheel still when braking on the front brake. Quick release forks with disc brakes should not be manufactured at all since they are a general danger. Unfortunately, such monsters are available for sale.

The problem is that the disc brake directs its braking force to cause ejection of the front wheel left axle end. The force is so great that it exceeds all forces at which quick releases are tested.

By tightening the quick release as much as you can and by using the best quick release you can buy (use a genuine Shimano component and not some knock-off brand), it is possible to make the left axle end appear to not move. This is just appearance; actually it moves slightly due to repeated brake applications, gradually wearing the left dropout. Then the quick release someday becomes so loose that the wheel ejects when you brake. Only if you repeatedly before every ride check the quick release tension and adjust as needed, can you prevent this.

This failure mechanism is well known.

The solution of the bicycle industry for this dangerous effect is to switch to thru-axles on disc brake bicycles. You should do the same; if you're planning to buy a disc brake bicycle, do ensure the front fork has a thru axle and not a quick release dropout.

Unfortunately, the fork you have cannot be used safely. It, as a fork lacking cantilever / V brake posts only allows disc brakes (and you don't want to ride a bike not having a front brake, relying only on the rear brake). The quick release dropouts on the other hand are not suitable for disc brakes. You might be able to somehow hack a caliper brake there assuming the reach is within the available reachs for caliper brakes.

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    Thanks for this answer, I am relieved there is a solution to this dangerous problem. So I will buy a new fork with a thru-axles, if you know a fork suitable to my surly frame, I will follow you lead. I am very surprised that Surly could sell this kind of fork, because as you said you should not have a fork with QR dropouts and a brake disk system. You kind of broke my irrational admiration for surly and I thank you for that.
    – Smilia
    Mar 30, 2021 at 18:35
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    Why do people downvoted this answer, could you please argument ?
    – Smilia
    Mar 30, 2021 at 18:42
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    1) Thousands of us are riding around every day with QRs and disk brakes and not having our front wheels fly off an kill us every time we stop hard. Many QR forks for disks now have slanted drops so the braking force doesn't line up directly with the opening. It is unfortunate this one is still being sold with vertical drops, but the overall situation is not the apocalypse you paint it as. 2) Shimano is not the only manufacturer on the planet that sells quality bicycle components. (and Shimano allows their name to be stamped on plenty of crap barely above BSO grade)
    – Affe
    Mar 30, 2021 at 21:21
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    @Smilia Although it is a valid concern (see yourself as an example), the wording is a bit harsh. Many, many people ride on QR disc brake bikes (myself included) and don’t have issues. Unless one has actually experienced dropout wear and/or slippage, there’s no reason to worry.
    – MaplePanda
    Mar 30, 2021 at 22:00
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    @Smilia that TA —> QR adaptor you bought on amazon does the opposite of what you want. You can’t just install a TA on a QR fork. You need a new fork with TA dropouts.
    – MaplePanda
    Mar 31, 2021 at 3:32

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