Odd Chain problem.

[neptune]

I have been somewhat bored lately. Then I realised that I have three grandsons, none of whom had a bike. So I started having a scrounge around for some cheap or free bikes that I could repair and pass on. The first on was a mountain bike, bought off facebook for a fiver. The rear wheel was so buckled it would not rotate in the frame. three spokes were broke, all on the cassette side of the wheel. I removed the cassette, and fitted three spokes from a wheel I found on a cycle path.It is now reassembled, and being used.

Bike number two was a gimme from a guy up the street, as he has bought a new one. It needed a clean,lube job, and a puncture repair. It is now up and running.

Number three was also a gimme. Owner bought a new one, and reports that the problem was gear slip. I found that by using all my strength, I could cause the chain to slip. At first, I thought it needed a new cassette and chain. It would only slip under hard acceleration. Then I noticed that the chain was actually slipping on the Front Chainwheel. Examination revealed that the middle chainwheel teeth were more worn than the other two chainwheels.

I had another bike in the shed that has been scrapped due to worn rear wheel bearings. I took the cranks and chainwheels off that one, [they looked good] and fitted them to bike three. Al;though I could not make it slip, my son in law, who is young and fit, tried it and said that with him, it slips enough to be a nuisance. I then changed the chain to the one off the scrap bike, reasoning that that chain, and the "new" chainwheels had previously been run together without problems. Son in law can still make it slip. Both chains look serviceable when measured for wear with a ruler.

I am running out of things to check. Rear derailleur is a bit battered, but changes reliably. There is some wear on the rear cassette, but that would not cause chain slip at the front chainwheel. The rear derailleur is good on the scrap bike, so I might swap it. The only thing I can think of is the chain tension adjustment on the rear derailleur.

The question is, has anyone had this problem before, and how was it solved?

 

[Alan Quay]

The chain and sprockets tend to wear together. I have had problems in the past that were only solved by a new chain & sprocket at the same time. I could not see any wear, but changing both solved all the slippage problems, and also made the gear changes better.

I don't tend to get as many problems with the front chainwheel.

 

[neptune]

Mike,It is true what you say about wearing together. The odd thing is though, that the chain and chainwheel now fitted to bike three were both previously in use together on the scrap bike. It was scrapped because of rear wheel bearing problems. It was previously used by my eighteen year old grandson, and the chain did not slip. The rear cassette is not from that scrap bike, but it is not the rear that is slipping. As I say, I am beginning to suspect chain tension. Many thanks for your input.

 

[john h]

Could be a bit of play in bottom axle, i would swap it out, checking they are both the same size , pity you where not near me as i have lots of spare parts wheels chainrings ect,

 

[neptune]

Hi John. Bottom bracket axle seems fine. My next step is to change the rear derailleur, as the original one is well worn, whereas the one from the scrap bike is like new. If this does not cure the problem, my grandson can still use the bike as long as he rides it sensibly. No hills for miles, and most grandson journeys are limited to a ride across town-two or three miles max. It saves my daughter acting as a taxi service for her kids, saves fuel, and gives the kids exercise.It also gives me something worthwhile to do.

 

[bigclick]

My old Diamond Back Topanga will be consigned to the skip soon...

... Last year it had new pedals and a bottom bracket cassette. Still has original chain and sprockets so they probaly need changing. Front tyre side walls are perishing. She has never totaly let me down.

Free to collect once I get my KTM.

 

[neptune]

@Bigclick.That is a kind offer. It is unlikely to be of benefit for me, owing to the distance involved, and the fact that i no longer drive. However, I am sure that there is someone local to you who could make use of it, rather than putting it in a skip. I sometimes dispose of unwanted bikes, simply by leaving them outside with a "Free to a good home" notice.Either local kids collect them, or the scrap man takes them to recycle, which is a less happy outcome. Either way, they disappear the same day.

Going back to my problem with "bike three", I have changed the rear derailleur. I am beginning to think that the frame is cracked somewhere, allowing it to flex under load, allowing the chain to slip.

What I am going to do next is to try to resurrect the scrap bike. It was scrapped because of total rear wheel bearing failure, and play in the bottom bracket. I have just stripped the bottom bracket, cleaned lubed, and adjusted it. Tomorrow, I will fit the wheels from bike three, along with the cranks chainwheels, derailleur and various bits. I think that this plan stands a good chance of success.

As well as providing the grandkids with bikes, the object of the exercise is to keep me amused without spending a lot of money. Also, to make me feel that although retired, I can still do something that others value.

 

[bigclick]

@Bigclick.That is a kind offer. It is unlikely to be of benefit for me, owing to the distance involved, and the fact that i no longer drive. However, I am sure that there is someone local to you who could make use of it, rather than putting it in a skip. I sometimes dispose of unwanted bikes, simply by leaving them outside with a "Free to a good home" notice.Either local kids collect them, or the scrap man takes them to recycle, which is a less happy outcome. Either way, they disappear the same day.

Going back to my problem with "bike three", I have changed the rear derailleur. I am beginning to think that the frame is cracked somewhere, allowing it to flex under load, allowing the chain to slip.

What I am going to do next is to try to resurrect the scrap bike. It was scrapped because of total rear wheel bearing failure, and play in the bottom bracket. I have just stripped the bottom bracket, cleaned lubed, and adjusted it. Tomorrow, I will fit the wheels from bike three, along with the cranks chainwheels, derailleur and various bits. I think that this plan stands a good chance of success.

As well as providing the grandkids with bikes, the object of the exercise is to keep me amused without spending a lot of money. Also, to make me feel that although retired, I can still do something that others value.

I like thr "free to good home idea" thanks

 

[neptune]

I think I may have solved this problem. I had swapped out all the transmission components on bike three and substituted components from the scrap bike. The only thing I had not changed was the freewheel. I noticed that sometimes the freewheel would not ratchet, it wanted to act like a fixed gear briefly.

I flushed it out with WD40, allowed it to drain, and oiled it. I noticed that it had a lot of play on the bearings, and you could wobble it. Its tendency to act as a fixed gear increased after cleaning and lubing. Also, I could make it slip under load.

I decide to remove the freewheel, but as it was "Suntour " type, I did not have the right tool. I decided not to buy a tool because I did not want to wait for the postman, and as these freewheels are not common, I might only use it once.

First I went to Halfords.He could not remove it, and as he took it into the back of the shop, I did not see him try. He did manage to slightly burr the slots where the tool fits, probably because he failed to use the wheel nut to secure the tool. At least he did not charge me.

Next port of call was the LBS.,He removed it in two minutes. He said "no charge" but I gave him a £3 tip.

I fitted theShimano freewheel off the scrap bike. On a road test, I could not make the drive slip.even on the smallest rear sprocket. Subject to a road test by a young strong rider, I think I have solved it. It will certainly work now as a local hack bike.

One lesson I have learned. when slipping of the transmission occurs, it can be very difficult to determine exactly what is slipping.