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For another pal!
the issue is he cannot get the correct chain tension on his bike. It has angled dropouts and runs a nexus hub. with the current sprockets and tyres he does not have enough adjustment - chain is either too slack when right at the back of the angled / slotted dropouts or remove a link and then the wheel is far enough forward that the tyre hits the frame!
He is thinking tensioner - but the frame does not have a dérailleur mount on it.
Is there a spring loaded tensioner that mounts on the rear axle?
Have you tried a half link chain?
no. Its the other option to put a half link in but are they not a bit shit?
You used to be able to get chainstay mounted ones, haven't seen one in years mind you.
crossed posts
Fast haggis - that looks ok
Edit - bolt up axle not QR so I think neither of those will work!
I don't suppose the frame has ISCG mounts?
Or how about an ETR-B
https://clee-cycles.co.uk/P1677/product
NOpe Scotroutes.
Bodge up a chain guide?
no. Its the other option to put a half link in but are they not a bit shit?
Never used them myself, but Google would suggest they might be.
What about an eccentric bottom bracket? You can get versions that fit some normal BB shells:
https://www.sigmasports.com/item/Wheels-Manufacturing/BB30-Eccentric-22mm-GXP-Bottom-Bracket/EQA4
https://www.bike-components.de/en/Trickstuff/Exzentriker-Bottom-Bracket-p25947/
I'd just use a BB mount stinger like this.
Would they really miss going up or down 1tooth on the sprocket or chainring to solve the problem?
half link ......... but are they not a bit shit?
A whole half link chain is a bit stretchy, but an individual link will be fine, just remember not to use narrow/wide chainrings.
I don't think that will work - its got a square taper BB using a shimano cartidge
Is this some bodged-together thing that's never going to work or was it supplied as a working bicycle? I mean, if it has angled dropouts, no EBB and a Nexus, how did it ever work?
We had a Specialized one on a Stumpjumper that went around the chain stay and put tension on the chain a couple of inches behind the chain ring.
Can't find a link but a search throws up a RSP one that looks like it does the same
"RSP Chain Director Chain Guide | Tredz Bikes" https://www.tredz.co.uk/.RSP-Chain-Director-Chain-Guide_76633.htm?sku=243457&utm_source=google&utm_medium=cpc&utm_campaign=google_shopping&gclid=Cj0KCQiAst2BBhDJARIsAGo2ldW5M9VV71vlxUnGJI1xZkGIcED5w1ev9sGNhwHyWFC8340WfOL0TZoaArp_EALw_wcB
People used to run chain guides with square taper BB's all the time a few years ago.
can we use a single half link with a 9spd chain? what width? ( they come in differnt sizes from what i see
Its not long since the whole drivetrain was replaced including fairly expensive chainrings and when we set it all up the wheel was almost at the back of the dropouts. I had hoped that when it wore a bit then we would be able to take a link out and get to the front of the dropouts
can we use a single half link with a 9spd chain? what width? ( they come in differnt sizes from what i see
You'll need a 3/32 chain:
https://www.sjscycles.co.uk/chains/jtek-chain-half-link-332-inch-each/
Which version of the nexus is it? I really would just get a new sprocket with one more tooth, they're £6 for the simplest ones and would solve the problem without the need for any additional bodging or parts.
Thats probably the best answer tinas - a new sprocket.
thanks for your help folks. Its not helped by the fact this guy is built like a rugby forward and mashes the pedals to death.
My stubborn refusal to do the sensible thing and get a proper tensioner has taught me this:
A half-link is a useful option but there is still enough slack to be an issue at some chainstay lengths/levels of wear
A chain ring or sprocket one tooth bigger or smaller is effectively a quarter-link, but that's still not a fine enough adjustment
A ghost ring is enough to take up any remaining slack that a half-link and one-tooth difference can't manage
As the chain wears the magic combination of half-link (or not)/extra tooth/ghost ring will change. A tensioner would likely deal with that
Could you use a bracket mount rear mech like this
https://www.amazon.co.uk/SHIMANO-INDEX-RD-TY15SS-DERAILLEUR-SPEED/dp/B00SJJ02F2
(sorry for the Amazon link, just gives you an idea of what it looks like)
Fits into a angled dropout and you could use limit screws to get the chainline right.
Bike Station will have loads if you just want to try it out.
WillTheRealForumPleaseStandUp
the bike has angled dropouts that allow the wheel to move back and forward - the problem is its not enough adjustment
boriselbrus
That would do - just the bracket bit would be better
Ta again folks
Ghost ring (floating idler) Different, if not a bit crazy 🙂
[img] https://www.mtbr.com/attachments/ghost-ring-jpg.1117392/ [/img]
I'd do as above and 1 tooth on the sprocket.
Full half link chains weigh a ton and I've seen them fatigue crack on the S bend in the plates (but think that was on 32:16 so maybe prone to stressing the same groups of links). Have also seen them burst where chain line was bad.
Alright, putting it another way...
If you limit yourself to adding or removing whole chain links then you need half an inch of adjustment to always be able to get the perfect chain length
If you are prepared to use/remove a half link as well then you need a quarter of an inch of adjustment
If you are prepared to use/remove a half link and change the sprocket by one tooth you need an eighth of an inch of adjustment
Maybe you have all you need but the gorilla stomping on the pedals is moving the axle. Also bear in mind that the chain will stretch so it won't stay perfectly adjusted for long
WillTheRealForumPleaseStandUp
I think you are missing the issue - he has it on different gearing to how it came originally so with a brand new chain you are already towwards the back of the adjustment range in the slotted dropouts. the chain has worn to the point it is right at the back of the dropouts but taking a whole link out the wheel is too far forward and hits the frame. the chain still has plenty of life in it.
Chainstay-mount wheel tensioner?
Or search for "emergency derailleur hanger" - MuckyNutz do one but there's loads on eBay.
I would (I did) remove a whole link and add a half link then.