A knocking sound?

eddieb

Hi, I have a Muddyfox bike. Slightly above what is bought in a supermarket . It is never ridden on any surface other than tarmac, i.e. paved bike paths and an occasional road. The bike is used for nothing more than exercise, about 14 to 20 miles a day ( I'm 64 and have a bad back). It is fitted with smoothies.
The gears are Shimano Tourney and whilst I appreciate they are at the bottom end of the scale, I keep them well tuned, cleaned and oiled weekly.
I have studied the Youtube videos re-gear setting and can say that my gears work faultlessly and extremely quiet. I'm pedantic about noise.
My question is as the above subject line states there is a knocking noise. I ride 99.9% of the time using the middle front spline and all of the rear gears. All gears except number five run silently. But as soon as I change into number five a knocking sound is heard . One knock per pedal revolution. It doesn't transmit through the pedals so I'm of the opinion its not the BB. It occurs only when the bike is ridden, no sound is heard when the pedals are wound on a bike stand.
The knock isn't really loud, but because the bike is so quiet the knock annoys me.
No knock if the pedals don't turn.
Apologies for taking so long to explain.
All help greatly appreciated.

Anonymous

No need to apologise, it's great to have someone fully explain for a change, instead of "ah, I have a noise, what is it?"

First thing that comes to my mind is a damaged tooth on the 5th gear on the cassette.
It might be pure coincidence that it works out as once per pedal revolution.

chedabob

Sounds quite similar to a problem I'm having at the moment, and I'm fairly certain the problem on mine is caused by the pivot bolt for the rear suspension (behind the bottom bracket) being loose.

nicklouse

eddieb
you say gear 5 but how many are there on the back. and the higher the number the smaller the cog?

unixnerd

Could it be the chain hitting the front derailleur?

eddieb

Gentlemen, many thanks for your replies.

Yeehaamcgee : Checked for damage, none. I should have said the bike is about three months old.

Chedabob : Mine is a hardtail , so no bolt.

Nicklouse : Remiss of me to fail to state number of gears.. 21 gears. Normal . Yes, gear seven is high.

Unixnerd : No, chain runs straight through the middle.

---

I hope I'm not stretching friendship, but I would like to ask another question, if I may!

Subject: Shimano gears, the price off and what justifies it.

I look each day on Ebay ( Retired with nothing to do and all day to do it in!!! ) And peruse the Shimano gears section. The prices vary enormously. I appreciate that true mtbs require top of the range and my type of mtb doesn't, but £434.00 for one Shimano RD?

regards,
Eddie

Chunkers1980

That's rubbish - even an XTR with the Gold Japanese stuff RRP is prob just over £200 - if you don't know what to look for, I'd steer clear of ebay - befriend your LBS instead.

nicklouse

eddieb wrote:

Nicklouse : Remiss of me to fail to state number of gears.. 21 gears. Normal . Yes, gear seven is high.

Mmm thats one idea out of the window. but i would hazzard a guess that the bearings in the hub or the freebody are on their way out/need a service. why only in 5? maybe the force inputed to the body id just at a level where it is causing a movement while in the other gears it is hidden.

Have a good look at the links in my sig (ParkTools and Sheldon) for some good how tos.

cooldad

eddieb wrote:

I hope I'm not stretching friendship, but I would like to ask another question, if I may!

Subject: Shimano gears, the price off and what justifies it.

I look each day on Ebay ( Retired with nothing to do and all day to do it in!!! ) And peruse the Shimano gears section. The prices vary enormously. I appreciate that true mtbs require top of the range and my type of mtb doesn't, but £434.00 for one Shimano RD?

regards,
Eddie

Decent new one - Deore or SLX should be between £20 and £35, from Ebay or CRC or similar. XT can be had for well under £50.
I ran an el cheapo Alivio for a few years on fairly rough stuff with no problems and for the sort of riding you do no need to spend silly money.
I have a Mountain DX on an old bike of mine - original 1985 Specialised, and it still works perfectly even at 25 yrs old.

eddieb

Chunker1980 - Rubbish not I'm afraid.
http://cgi.ebay.co.uk/New-Boxed-2010-Sh ... 5ad6349dcd

Cooldad, I am not looking to buy, simply perusing, just for something to do. I have no need of a new gear.

Nicklouse, thanks for that . Although I look there all the time, I find their advice very good.

Anonymous

£424 for a rear mech? holy cow :shock:

stubs

yeehaamcgee wrote:

£424 for a rear mech? holy cow :shock:

+1 with big knobs on

Imagine whacking that against a tree stump you'd hang yourself

peter413

1. thats is a road mech is it not

and 2. it is for that new fanggled electronic shifting I believe so its new technology so obviously expensive

bails87

peter413
Spot on!

5pudgun

If it's one knock per pedal revolution, I'd guess your pedal is catching something when your in said gear,rather than a problem with the gear itself.Like yourself I'm paranoid about unwanted noises,had a similar problem recently which turned out to be a couple of loose allen keys in my pocket that clicked together on the upstroke :oops: