<form class="form-filter" method="get" action="@Url.Action("BikeFilter", "Home")">

<input type="hidden" name="catId" value=1>

    <div class="form-inline filter">

        <label>Wheel size:</label>

        <select name="SelectWheelSize">

            <option selected></option>

            @foreach (var item in ViewBag.WheelSizes)

            {

                <option value="@item">@item</option>

            }

        </select>

        <input type="submit" value="Apply" class="btn btn-success btn-sm"/>

    </div>

</form>