I dont think its is the Townie. I originally had a mountain bike and my back hurt alot on that bike. I borrowed a townie for a while and it did not bother me so i bought one. It seems with biking uphill at all and doing situps at home, I have done some pulling. I will find out mor thursday . I ahve had back issues for many years, but now its getting worse. I have been in spasm for 7 days now.