diff --git a/curl.go b/curl.go
index 5270d23..56c96a3 100644
--- a/curl.go
+++ b/curl.go
@@ -40,6 +40,7 @@ func (r *Request) Clone() *Request {
 			bodyFileData:          CloneFiles(r.bodyFileData),
 			queries:               CloneStringMapSlice(r.queries),
 			bodyDataBytes:         CloneByteSlice(r.bodyDataBytes),
+			customTransport:       r.customTransport,
 			proxy:                 r.proxy,
 			timeout:               r.timeout,
 			dialTimeout:           r.dialTimeout,
diff --git a/curl_default.go b/curl_default.go
index 5c14c6c..55a48ae 100644
--- a/curl_default.go
+++ b/curl_default.go
@@ -22,6 +22,7 @@ var (
 	DefaultDialTimeout   = 5 * time.Second
 	DefaultTimeout       = 10 * time.Second
 	DefaultFetchRespBody = false
+	DefaultHttpClient    = NewHttpClientNoErr()
 )
 
 func UrlEncodeRaw(str string) string {
@@ -59,39 +60,39 @@ func BuildPostForm(queryMap map[string]string) []byte {
 }
 
 func Get(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "GET", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "GET", opts...).Do()
 }
 
 func Post(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "POST", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "POST", opts...).Do()
 }
 
 func Options(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "OPTIONS", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "OPTIONS", opts...).Do()
 }
 
 func Put(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "PUT", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "PUT", opts...).Do()
 }
 
 func Delete(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "DELETE", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "DELETE", opts...).Do()
 }
 
 func Head(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "HEAD", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "HEAD", opts...).Do()
 }
 
 func Patch(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "PATCH", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "PATCH", opts...).Do()
 }
 
 func Trace(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "TRACE", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "TRACE", opts...).Do()
 }
 
 func Connect(uri string, opts ...RequestOpt) (*Response, error) {
-	return NewSimpleRequest(uri, "CONNECT", opts...).Do()
+	return NewSimpleRequestWithClient(DefaultHttpClient, uri, "CONNECT", opts...).Do()
 }
 
 func DefaultCheckRedirectFunc(req *http.Request, via []*http.Request) error {
diff --git a/curl_test.go b/curl_test.go
index 37baec3..e34b79a 100644
--- a/curl_test.go
+++ b/curl_test.go
@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 )
 
 func TestUrlEncodeRaw(t *testing.T) {
@@ -567,7 +568,7 @@ func TestTlsConfig(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	req := NewSimpleRequestWithClient(client, server.URL, "GET", WithHeader("hello", "world"))
+	req := client.NewSimpleRequest(server.URL, "GET", WithHeader("hello", "world"))
 	//SetClientSkipVerify(client, true)
 	//req.SetDoRawClient(false)
 	//req.SetDoRawTransport(false)
@@ -601,3 +602,50 @@ func TestTlsConfig(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestWithTimeout(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+		time.Sleep(time.Second * 30)
+		rw.Write([]byte(`OK`))
+	}))
+	funcList := []func(string, ...RequestOpt) (*Response, error){
+		Get,
+		Post,
+		Put,
+		Delete,
+		Options,
+		Patch,
+		Head,
+		Trace,
+		Connect,
+	}
+	defer server.Close()
+	for i := 1; i < 30; i++ {
+		go func(i int) {
+			old := time.Now()
+			fn := funcList[i%len(funcList)]
+			resp, err := fn(server.URL, WithTimeout(time.Second*time.Duration(i)))
+			if time.Since(old) > time.Second*time.Duration(i+2) || time.Since(old) < time.Second*time.Duration(i) {
+				t.Errorf("timeout not work")
+			}
+			fmt.Println(time.Since(old))
+			if err == nil {
+				t.Error(err)
+				resp.CloseAll()
+			} else {
+				fmt.Println(err)
+			}
+		}(i)
+	}
+	resp, err := Get(server.URL, WithTimeout(time.Second*60))
+	if err != nil {
+		t.Error(err)
+	} else {
+		fmt.Println(resp.Body().String())
+		if resp.StatusCode != 200 {
+			resp.CloseAll()
+			t.Errorf("status code is %d", resp.StatusCode)
+		}
+		resp.CloseAll()
+	}
+}
diff --git a/curl_transport.go b/curl_transport.go
index 08ff99b..e14ae6d 100644
--- a/curl_transport.go
+++ b/curl_transport.go
@@ -27,6 +27,11 @@ func NewHttpClient(opts ...RequestOpt) (Client, error) {
 	}, err
 }
 
+func NewHttpClientNoErr(opts ...RequestOpt) Client {
+	c, _ := NewHttpClient(opts...)
+	return c
+}
+
 func NewClientFromHttpClient(httpClient *http.Client) (Client, error) {
 	if httpClient == nil {
 		return Client{}, fmt.Errorf("httpClient cannot be nil")
@@ -109,6 +114,32 @@ func (c Client) SetDefaultTLSConfig(tlsConfig *tls.Config) {
 	}
 }
 
+func (c Client) NewRequest(url, method string, opts ...RequestOpt) (*Request, error) {
+	if c.Client == nil {
+		return nil, fmt.Errorf("http client is nil")
+	}
+	req, err := NewRequestWithContextWithClient(context.Background(), c, url, method, opts...)
+	return req, err
+}
+
+func (c Client) NewRequestContext(ctx context.Context, url, method string, opts ...RequestOpt) (*Request, error) {
+	if c.Client == nil {
+		return nil, fmt.Errorf("http client is nil")
+	}
+	req, err := NewRequestWithContextWithClient(ctx, c, url, method, opts...)
+	return req, err
+}
+
+func (c Client) NewSimpleRequest(url, method string, opts ...RequestOpt) *Request {
+	req, _ := c.NewRequest(url, method, opts...)
+	return req
+}
+
+func (c Client) NewSimpleRequestContext(ctx context.Context, url, method string, opts ...RequestOpt) *Request {
+	req, _ := c.NewRequestContext(ctx, url, method, opts...)
+	return req
+}
+
 type Transport struct {
 	base *http.Transport
 }