Reserve Bank of New Zealand deputy governor Grant Spencer has reassured banks that the RBNZ's recently announced speed limit on riskier mortgages is only temporary and the central bank has no intention of "micro-managing" bank lending. Speaking at a news conference to discuss the release of the RBNZ's September quarter Monetary Policy Statement, Spencer said the limit on high loan-to-valuation ratio lending was only a temporary measure. Spencer said: "Our intention is to avoid excessive cyclical effects from credit expansion. There is always going to be some cyclical effect from the housing cycle and the credit cycle."New Zealand banks will have to restrict new residential mortgage lending at LVRs of over 80 per cent to no more than 10 per cent of the dollar value of their new housing lending flows."We certainly have no intention of managing that on a detailed or micro basis," Spender said."We've put things in place like increasing risk weights for the higher LVR lending, which will help to moderate the cycle on an ongoing basis."This is a temporary measure, a transitional measure for this situation. Eventually it will be taken off and then the existing prudential policies will play their part to moderate their risk of high LVRs. It won't be an ongoing process of micro-managing the credit books of the banks."The bank has always proposed that it would be temporary, but the comments from Spencer are the most explicit yet about the rationale for when it might be removed.Later in an appearance before Parliament's Finance and Expenditure select committee, Spencer said he could not say how long the speed limit would be in place, but said the effects were most likely to be felt in the first year."Within six months we'll have an indication," he said. The  RBNZ's Monetary Policy Statement also noted some signs of stabilisation in the housing market in the past few months, but did not link it to the impending announcement of the speed limit. Mortgage lending growth slowed through June, July and August as banks prepared for the imposition of the speed limit, which was announced on August 20 and applies from October 1.Governor Graeme Wheeler also told the select committee the limits could eventually be removed. "We will remove them when we get a better balance in the housing market and when we're sure that a removal won't lead to a resurgence in house price inflation," he said.