NeilnrLincoln
Well-Known Member
- Location
- Lincoln
I'd be perfectly happy to run that. With single chainring & no rear suspension it cant ever get any tighter.
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U
User33236
Guest
Presumably it had a chain fitted before? Unless of course it's new build you are doing.
How many links did the old chain have?
Personally, whilst it works, I be more concerned about undue strain in the RD return spring if repeatedly getting pulled close to its limit.
How many links did the old chain have?
Personally, whilst it works, I be more concerned about undue strain in the RD return spring if repeatedly getting pulled close to its limit.
Yellow Saddle
Guru
- Location
- Loch side.
That chain is too short by one link. Although it will work sortof OKish, it will be noisy in that gear and will prematurely wear the tension pulley by thinning it on the sides and creating a blade-like profile that wears very quickly. Such a pulley is also prone to derailing.
Your original photo doesn't really show the whole picture. One has to be able to see the jockey cage angle wrt to the horizontal. It should bend forward no more than 45 degrees in the extreme gear combo and point back no more than just-just below horizontal in the extreme gear combo the other way.
You may be surprised to see how big a difference a single link makes. Fix the problem. Happy bike, happy life.
Your original photo doesn't really show the whole picture. One has to be able to see the jockey cage angle wrt to the horizontal. It should bend forward no more than 45 degrees in the extreme gear combo and point back no more than just-just below horizontal in the extreme gear combo the other way.
You may be surprised to see how big a difference a single link makes. Fix the problem. Happy bike, happy life.
Cubist
Still wavin'
- Location
- Ovver 'thill
Just to weigh in, it will run like that on a hard tail, my rule of thumb is to see a defined s shape through the jockeys in the big cog, and no "folding back on itself with no tension" in small. However, it would bear running one extra link. Before you whip out the splitter, make sure you have the b screw dialled correctly. You need to see about 7-8mm of daylight between the top tooth of the top jockey, and the lowermost tooth of the cog in lowest gear.
Is it a clutch mech? Can't tell on a phone screen.
Edit. Yep, clutch mech, and b tension looks close enough in the top pic.
It would withstand a whole new link, (both halves). Try it as it is and get some fast and violent up and down shifts going in the workstand. Any issues will show up there, rather than when I used too short a chain on the mojo and it threw the mech into the spokes at Cannock!
Is it a clutch mech? Can't tell on a phone screen.
Edit. Yep, clutch mech, and b tension looks close enough in the top pic.
It would withstand a whole new link, (both halves). Try it as it is and get some fast and violent up and down shifts going in the workstand. Any issues will show up there, rather than when I used too short a chain on the mojo and it threw the mech into the spokes at Cannock!
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Smokin Joe
Legendary Member
- Location
- Bare headed cyclist, Smoker
Clutch mechs are more common on mtn bikes now. They put extra tension on the chain to stop it bouncing off or rattling on rough ground.
And I'd still put two links in that.
Thanks again for the response.
I think I'm tending towards putting a pitch back in, the only reservation being putting in a joining pin (I'm already using a SRAM split link) and introducing a possible failure point.
Maybe I'll ride it as it is til the autumn, and replace it with a slightly longer one. It does seem to change gear just fine.
I think I'm tending towards putting a pitch back in, the only reservation being putting in a joining pin (I'm already using a SRAM split link) and introducing a possible failure point.
Maybe I'll ride it as it is til the autumn, and replace it with a slightly longer one. It does seem to change gear just fine.
Yellow Saddle
Guru
- Location
- Loch side.
It is a type of damper to reduce chain slap when the bike is going over homogeneous ruts. This type of ruts in the road create a harmonic wave in the chain that amplifies normal chain shake (up and down). The clutch dampens the spring in the RD in one direction so that it is difficult for the chain to "pull length" but easy for it to return to its original position. It is like a one-way damper on a suspension fork. This clutch reduces chain slap noticeably but has the side effect of making shifts (usually up shifts) more difficult since your thumb now has to overcome some friction in the mechanism that gives slack to the chain when required. They have on/off mechanical switches located on the RD itself.
Yellow Saddle
Guru
- Location
- Loch side.
I want to emphasise that it isn't all about shifting but mostly about reliability and wear. If you carefully aim along the chain's natural line on the return run and eyeball the plane of the jockey wheel, you'll notice that in the extreme big sprocket at the back, the jockey wheel doesn't follow the chain's line perfectly but wants to steer left. With shortening of the chain, this angle is accentuated and the tension pulley constantly wants to derail. You'll hear that it makes a different sound when it does that. This wears out the wheel but more importantly, poses a risk of the pulley derailing and ripping your RD out and into the spokes. The risk increases with wear and dramatically so.
This is simply a by-product of derailer design. You'll notice that manufacturers compensate for this phenomena by off-setting the tension pulley to the right. This offset is completely negated as the return run shortens beyond a point that's usually indicated by a 45 degree angle in the jockey cage.
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raleighnut
Legendary Member
- Location
- One of the 'Elite'
