Low-speed knocking?

**Aa7** · 15th January 2009, 11:36

ok so I haven't had a look at anything so far as I only heard this for the first time this morning . I noticed that my bike is making a weird knocking sound from somewhere while riding at low speeds and in first gear or while moving the bike in neutral and idle. I was going to look into it further when I get home tonight but wanted a few pointers where and what to look at before I get into it.

I hadn't noticed it before but it seems to only happen when I am in 1st gear and slowing down or moving slowly like when I sit on it idling and back it into it's parking space as when I heard it I took it around the block slowly again and noticed it only when moving slowly almost walking speeds. It sounds like a repetitive spaced low speed knock almost as if the wheel was buckled if that makes sense. Sort of like when a mountain bike wheel is bent and the rim scrapes the brake pads at the same point on every wheel revolution but a knock rather than a scrape sound if that helps at all... other than that I dont have much information or idea where to look really. Any ideas where to look first or what it may be???

**Ixion** · 15th January 2009, 11:40

What sort of bike is it? And, without being 'smart' ,do you have much experience of bike mechanicals ?

I ask because my first instinct is chain, but that , of course, presumes you have one! And I would also imagine that a biker of many years experience would be on to that immediately, so if that be the case it is something more internal.

**Aa7** · 15th January 2009, 11:46

Doh, that may help..... not a mechanic as such but not a complete office case either

hahahah

It's a fat and lazy RF900. I looked at the chain first too as it was lubed and adjusted a few days ago so I thought maybe that I'd not tightened it back enough and it had slipped or misaligned the wheel but that all seems good and tight using the eyecrometer and boot lift adjustment check. Will double check this though when I get home with some tools. Any other ideas...

**Ixion** · 15th January 2009, 12:09

Lots of possibilities really.

You say you hear if you wheel the bike in neutral with the motor idling. Do you also hear it if you wheel the bike in neutral with the motor off? If so, we may reasonably exclude motor and gearbox. If not (ie it only happens with the motor running) then either the motor itself or, more likely, the 'shaking' of the motor is causing bit A to hit bit B

In my experience 70% of funny noise sat low speed are due to chains. Often being too tight when the chain has a 'tight' spot.

Could be a loose brake caliper, bud wheel bearing, lots of things. But check out the simple stuff first.