Tight Spot on new chain and sprockets

[Sppete]

That's got to be the chain
If it was the rear sprocket,sprocket holder or wheel bearing is a bit oval, the chain would go tight every one revolution of the wheel. If it goes tight every revolution of the front sprocket ( nearly 3 x per revolution of the rear wheel) it would be a final drive problem but everytime the chain comes back to the same spot has to be the chain
There are only two ways I can think of to check it
1) get a micrometer and measure the distance between the centres of each link.
2) Check each individual link for tightness.
It could just be the chain is fine and either the grease is a bit thick at one point or the links are a bit tight and it just needs a little "running in" to loosen them up. Definitly a bit of a mystery though.

Pete

[steelsey]

Well I refused to believe it could be the sprocket especially now I have used 2 new chains and tried 2 new sprockets. After much deliberation I came to the conclusion it must be the carrier or the bearing. So I bought a 2nd hand carrier complete with bearing and fitted to the bike. 100% certain that would cure the problem. I mounted it up, set the chain and span the wheel. My heart sank as the same tight spot occurred. This time i meant business and fitted the old worn sprocket, and without the chain, I span the wheel and studied the sprocket, I saw no deflection at all. I then mounted the new Renthal sprocket and span the wheel, again with no chain. This time I saw movement both lateral and linear! I took the Renthal sprocket off and using a vernier gauge I measured from the troughs of the teeth to the inside edge of the chain ring. I locked down the vernier so the gauge would not move and worked my way around the sprocket only to find that it would only sit in a few before the gap between the troughs and inside edge of the chain ring grew as I made my way around the sprocket. This has to be the cause of the tight spot. The measurement varied from 28.7mm up to 29.3mm.

I don't know what to do? the entire chain and sprocket fit so far has cost me way too much! I want to go back to a standard chain and sprocket but I can't afford to do a u-turn now and I can't see another Renthal sprocket being any different! I'm not been picky or anal about the tight spot, after much frustration I nearly decided to run it like that but after running the bike in 2nd gear on the stand the tight spot caused such a violent whipping of the chain I simply would not dare to run it like that.

Has anyone on here got Renthal 520 sprockets? what you recommend doing?

Thanks

Rich

[CROOKY]

Renthal have a new machine for doing the sprockets to reduce the amount of ops on each one.I run my own engineering company and the write up was in a trade mag that i get.The old way they made them could easily account for a 0.6mm run out.But 0.6mm run out should not cause tight spots when you have 20mm of slack on the chain.Is the pitch on the chain the same as the module on the sprocket.

[steelsey]

Renthal have a new machine for doing the sprockets to reduce the amount of ops on each one.I run my own engineering company and the write up was in a trade mag that i get.The old way they made them could easily account for a 0.6mm run out.But 0.6mm run out should not cause tight spots when you have 20mm of slack on the chain.Is the pitch on the chain the same as the module on the sprocket.

Thanks for the reply, Yeah I bought the renthal 520 kit from B&C express. The tight spot always occurs in the same place on the rear sprocket on each revolution.

[steelsey]

Fixed it! I bought a Talon sprocket!!!! Got it today, fitted it, set the chain and all is good. I can't believe how out the Renthal wass I've been a big advocator of their products for years. They were great though and offered to take the sprocket back and refund me my money

[Dmac]

Good news

Well done on persevering with it,

It's amazing how frustrating these things can be - and seem easy when there fixed.
- like looking for lost keys-- easy after you have found them.

[Sppete]

Result!

They must have a bad batch, maybe I'll give Renthal a miss this year
I'm going to have to replace mine at some time this summer

Pete