concurring:
On January 31, 1975, the appellant was convicted by a jury of violating the Controlled Substance, Drug, Device and Cosmetic Act.1 A timely motion in arrest of judgment was refused by the lower court, and sentence was pronounced. The appellant now questions the propriety of this conviction, raising several allegations of error. *231After careful review, I would reject the appellant’s contentions, and affirm the judgment of sentence.
On March 21, 1974, a written complaint was filed against the appellant charging him with selling a quantity of the controlled substance methamphetamine (speed) to an undercover agent of the Pennsylvania State Police on two separate occasions. On June 10, 1974, a Grand Jury returned two bills of indictment against the appellant, each charging him with possession and sale of a controlled substance. Although the case was listed for trial on October 7, 1974, trial was not held at that time because of the backlog of criminal cases in the court below.2 On November 27, 1974, the Commonwealth filed a petition for an extension of time for commencement of trial pursuant to Pa.R.Crim.P. 1100(c).3 In its petition, the Commonwealth asserted that it had exercised due diligence in bringing the appellant to trial, attributing the responsibility for the delay solely to the judiciary. The prescribed time period expired on December 16, 1974; however, the lower court delayed its decision on the Commonwealth’s petition until December 20, 1974, when it granted the Commonwealth an extension of time. Trial commenced on January 31, 1975, or 315 days after the written complaint was entered against the appellant. The appellant first contends that his right to a speedy trial was denied in that he had not been brought to trial within 270 days from the date the criminal complaint was filed against him, as required by Pa.R.Crim.P. *2321100(a)(1).4 The majority, citing Commonwealth v. Mayfield, 469 Pa. 214, 364 A.2d 1345 (1976), and Commonwealth v. Shelton, 469 Pa. 8, 364 A.2d 694 (1976), finds that the “prosecution’s” petition for an extension of time was properly granted by the lower court. I find that the appellant has waived his right to argue a Rule 1100 violation and is therefore precluded from questioning the propriety of the lower court’s grant of extension. I believe, therefore, that the majority errs by reviewing this issue.
The record clearly shows that the appellant failed to comply with the requirements of Section (f) of Pa.R. Crim.P. 1100, which provides, in pertinent part, that:
“[A]t any time before trial, the defendant or his attorney may apply to the court for an order dismissing the charges with prejudice on the ground that this Rule has been violated.”
Although Rule 1100(f) requires an accused to file a petition to dismiss before trial showing that the prescribed time period has expired, the appellant did not formally assert his right to a speedy trial until after trial in a motion in arrest of judgment. A petition to dismiss the charges was never filed.
Rule 1100(f) provides the exclusive method by which an accused in this Commonwealth may gain relief from a denial of his right to a speedy trial.5 Under Section (f), an accused may petition the court below for an order *233dismissing the charges only if such petition is filed prior to trial and after the expiration of the prescribed period. In his answer to the Commonwealth’s petition for an extension of time, the appellant requested that the charges be dismissed for want of prompt prosecution. However, because the appellant’s right to a speedy trial had not been violated when he filed his answer, the appellant’s answer does not satisfy the requirement of Rule 1100(f), as promulgated by our Supreme Court, that an accused’s petition for dismissal be predicated upon a violation of the prescribed time period. Rule 1100(f) mandates that the issue of a speedy trial denial be clearly preserved by means of a timely petition. The appellant did not follow the prescribed procedure. Therefore, I believe that he forfeited his right to argue a violation of Rule 1100. See Commonwealth v. Sprankle, 241 Pa.Super. 298, 361 A.2d 385 (1976) (dissenting opinion).
The appellant next contends, pro se, that his trial counsel was ineffective because he failed to call a witness who would have allegedly impeached the testimony of the Commonwealth’s witnesses. I find this contention to be without merit.
At trial, the Commonwealth’s evidence against the appellant primarily consisted of the testimony of two undercover police agents. Each agent testified that he had been informed by a person named “Butter Roy or Ray” that appellant was in possession of drugs available for sale. After receiving this information, each agent approached the appellant and purchased a controlled substance from him. The agents also testified that the informant was not present during either transaction. The appellant alleges that prior to trial he had advised his trial counsel that the informant was a prison inmate named James Lee, who would provide testimony contrary to that of the agents, namely, that he had never informed the agents that the appellant would sell them drugs. The appellant’s trial counsel never called James Lee as a wit*234ness. The appellant’s denial of the above events constituted his sole defense.
“[O]ur inquiry ceases and counsel’s assistance is deemed constitutionally effective once we are able to conclude that the particular course chosen by counsel had some reasonable basis designed to effectuate his client’s interests.” Commonwealth ex rel. Washington v. Maroney, 427 Pa. 599, 604, 235 A.2d 349, 352 (1967). The record clearly shows that trial counsel was reasonable in his decision not to place James Lee on the witness stand. Trial counsel would have had great difficulty in proving that James Lee was the informant in question. On cross-examination, one of the police officers testified that although the informant’s “nickname was ‘Butter Roy’; his real name was Ritchie Rivers,” not James Lee. The appellant, on the other hand, does not demonstrate the basis for his assertion that James Lee was in fact the informant. Furthermore, trial counsel could have permissibly concluded that James Lee, who was then incarcerated, was at best of questionable character, and that his client’s interests would be harmed, rather than benefited, by seeking to use James Lee as a means of impeachment.
The appellant additionally seeks to establish that the evidence adduced at trial was insufficient to sustain the conviction. The appellant did not raise this issue in his post-trial motions. The issue is therefore waived and cannot be raised in an appeal to this court. E. g., Commonwealth v. Bronaugh, 459 Pa. 634, 331 A.2d 171 (1975).
I would affirm the judgment of sentence.
. Act of April 14, 1972, P.L. 233, No. 64, § 1 (35 P.S. § 780-101) et seq.
. The record clearly shows that the appellant was In no way responsible for any period of delay in being brought to trial.
. Pa.R.Crim.P. 1100(c) provides in pertinent part:
“At any time prior to the expiration of the period for commencement of trial, the attorney for the Commonwealth may apply to the court for an order extending the time for commencement of trial. . . Such application shall be granted only if trial cannot be commenced within the prescribed period despite due diligence by the Commonwealth.”
. Pa.R.Crim.P. 1100(a)(1) provides:
“Trial in a court case in which a written complaint is filed against the defendant after June 30, 1973 but before July 1, 1974 shall commence no later than two hundred seventy (270) days from the date on which the complaint is filed.”
. It is well established that failure to object properly constitutes a waiver of the right to a speedy trial. See Commonwealth v. Roundtree, 458 Pa. 351, 326 A.2d 285 (1974), and cases cited therein. Prior to Rule 1100, an objection to the length of delay in being brought to trial was properly raised in a pre-trial motion to quash the indictment. E. g. Commonwealth v. Gates, 429 Pa. 453, 240 A.2d 815 (1968). See Pa.R.Crim.P. 304.