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Possible to fit 20mm stem-mounted adapter for child seat?

  • 03-04-2022 6:38pm
    Registered Users Posts: 4,031 ✭✭✭

    Looking to get a Thule Yepp Mini Front Child Seat (here) for my wife's bike. It's a stem-mounted seat which gets excellent reviews. Using this adapter (here) it needs 20mm of stem height.

    There are currently 2 x 5mm spacers in place so it needs another 10mm of space. Given it's a steel steerer tube, can this work, or given the stem clamp will then have 10mm less of steerer tube to clamp onto, is this an issue? I reckon it is an issue but appreciate any thoughts as the Yepp Mini would seem to be the handiest solution as the stem-mounted adapter means the child seat can easily be installed and removed in seconds.

    I'm not familiar with this type of headset: when I removed the headset cap I thought there'd be another allen bolt beneath to remove to loosen the headset but I inserted a 140mm long allen key and didn't detect anything. What are the steps for loosening this headset in the event I did want to remove the spacers and install the stem-mounted adapter?

    My wife's bike is a Creme Cycles Eve E-bike (here) for anyone interested - in the flesh it is an absolutely stunning bike, the little finishing details are sumptuous, surprised not to have seen any of them around Ireland to-date. Don't want to spoil the looks by having a child seat permanently installed so preference is to get the Thule Yepp Mini mounted on the stem, but am all ears if there's other nifty options we haven't come across yet. Thanks


  • Registered Users Posts: 168 ✭✭Al Wright

    It's difficult to be sure, but the picture on Thule website appears to show the seat fitted to a bike with a quill stem, while yours is an Ahead type.

    A quill stem inserts down into the steerer tube and is held in place by a bolt & wedge.

    The Ahead is held in place by the angle stem (clamp with the 2 screws) which clamps on to the end of the steerer tube just on top of the 2 spacers shown in your photos. Your first photo shows the spring steel stellated nut, which is designed to be pushed down into the steerer tube and grip there, its function being to hold on the top cap. (photo 3)

    I don't think that this seat will fit your bike, but it may be worth while checking with Thule

  • Registered Users Posts: 3,990 ✭✭✭68 lost souls

    Something like this might work but there are caveats of the windshield bit working with it

  • Registered Users Posts: 190 ✭✭Jonesy101

    I have the ahead adaptor fitted to a moutain bike, Merida big trail 600. i think it would fit, only thing is that your stem looks quite wide. the U clamp part on the ahead adapter (link above) might not be wide enough, if you could measure exactly the width of your stem i could measure the inside width of the U clamp on my one for you if you pm me. ( @ me. not sure how it works on this)

  • Registered Users Posts: 4,031 ✭✭✭FrankGrimes

    Completely forgot about this thread and now have my other half on my case (and rightly so!).

    Thanks for that info Al Wright, very helpful to know it's an Ahead stem. So it looks like to remove the spacers I remove the bolt(s) that are running horizontal/parallel to the ground in the out front section (i.e. in the hinge joint), then loosen the top cap bolt, take off the stem/handlebars, then remove the spacers, then install the Thule adapter, refit the stem/bars, tighten the horizontal bolts, then tighten the top cap?

    Does the spring steel stellated nut just stay where it is or is there anything I need to do with that?

    I'm going to go ahead and order the Thule adapter and see if it fits and then make a call on whether it looks like the seat will actually fit and order the seat if so, worst case I have to return it and then go with another model.

  • Registered Users Posts: 4,031 ✭✭✭FrankGrimes

    Thanks for this Jonesy101 - looking at it, I reckon the stem will be too wide for that clamp, but will measure it tomorrow and see if it's a runner.

    If the Thule doesn't work, I'm looking at this Polisport option or this Bobike Go Mini - though neither looks as neat and tidy as the Thule option so fingers crossed that's a runner - just posting here in case anyone looking at the thread has experience of either option they can share. Thanks

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  • Registered Users Posts: 4,031 ✭✭✭FrankGrimes

    The Ahead stem is 42mm pretty much square so judging by the look of it that u-adapter isn't going to fit so will look at the other options.

  • Registered Users Posts: 168 ✭✭Al Wright

    The spring steel stellated nut remains, its function is to retain the top cap in place, it is not load bearing.

    Take care not to move the frame when the handlebar clamp is removed, it also holds the steerer tube/forks in place, there is small risk of disturbing the head bearings.