ichabodcr

Issue with chain tensioner - New inspired Fourplay Pro 2020

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Hi Everyone,

I've just bought a brand new Fourplay Pro 24'', can't wait to be able to ride it, but I came up against an issue when putting it together from the delivery box.

Basically the lower sprocket of the chain tensioner rubs against the chainstay if aligned correctly. If I move it inwards a few mm then it does not rub (but it's very close indeed), but the chain is not in line any more and I'm sure it would end up wearing badly very quickly if used that way.

See pic, and a youtube video with no rubbing bad "bad" chain line. 

 

 

My question is: how do I solve this? I'm going to call TartyBikes (I got it from there), but I believe the problem is that the chain is a few links short, if it was longer than the tensioner would be a bit more relaxed, and the lower sprocket would stay well BELOW the chainstay.

Any other ideas? Am I missing something obvious? I've never had a single speed bike with tensioner before so I'm very new to this and could just be doing something very silly...

 

cheers!

IMG_20201121_095858293.jpg

Edited by ichabodcr
correction

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Having the chain as short as possible is desirable in trials. It keeps everything nicely tight and compact, and stops it all flapping around so much on landing.

To be honest, the video clip looks fine. I'm not super familar with those bikes but a lot of the clearances can get pretty close in on trials bikes. If it's close but it clears, it's fine.
At that angle, the chainline didn't look too bad. Could you post a picture down the length of the chain to show how "bad" it is?

I get the impression you have an MTB background... if that is the case, just know that single-speed bikes with comparatively wide chains have a lot more tolerance in chain-line.
Definitely worth getting in touch with Tarty as their service is great and it might be an actual issue, but I'd be happy enough with riding that.

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Thanks for calling and emailing Pablo, glad we have it cleared up for you already.

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Cheers guys for clearing this up for me.

Thumbs up for TartyBikes after-sales support, super quick and helpful.

This is a pic that shows how I would have it set up for the sprocket to clear the chainstay (by barely a mm maybe..)

 

If you say it's fine I'll stop worrying about it. I just did not want to do something stupid and go out and damage the new bike straight away by riding it whilst badly adjusted.

And yes, you're right.. I come from a mountain-biking backgroud so I'm just totally ignorant about how a trials bike is set up correctly.:D

 

IMG_20201121_095831890_HDR (1).jpg

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Not sure what advice Tarty gave you but I’m glad it helped, one thing to note in case they didn’t mention it (and to save others from calling them) that chains do stretch so after a couple of hard riding sessions the chain/tensioner should sit further away from the frame which would help fix the clearance issue :) 

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3 hours ago, Ali C said:

Not sure what advice Tarty gave you but I’m glad it helped, one thing to note in case they didn’t mention it (and to save others from calling them) that chains do stretch so after a couple of hard riding sessions the chain/tensioner should sit further away from the frame which would help fix the clearance issue :) 

The advice was not to worry about it and ride it. It's fine as shown in the pictures/video. Chain line might not be perfect but that was just me being over-zealous I guess. Also, I only ever messed with bikes with derailleurs and thinner chains, where the chain is either dead straight or ends up jumping all the time.

I went for a first test ride today and indeed it was perfectly fine. :D

Thanks everyone for the advice and support! :lol:

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Glad I saw this thread because although my chain on my '19 Fourplay is a bit longer so the sprocket sits lower the actual sprocket and chain alignment looks just like yours, ie: it looks a bit off. As I bought my bike second hand I assumed the tensioner was a bit bent but as yours is the same then mines probably also fine. 

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On 26/12/2020 at 6:05 PM, Rip said:

Glad I saw this thread because although my chain on my '19 Fourplay is a bit longer so the sprocket sits lower the actual sprocket and chain alignment looks just like yours, ie: it looks a bit off. As I bought my bike second hand I assumed the tensioner was a bit bent but as yours is the same then mines probably also fine. 

Yeah, these things are always a bit crooked. My OCD couldn't handle it, so I've taken some inspiration from Ali C and made his style of chain tensioner from a plate of titanium. Looks cleaner, weighs less, and makes a lot less noise when bouncing around.

Only thing I find with tensioners that occasionally after a rough bounce without pedal pressure, and then putting pressure on the pedals, the chain will sometimes make a single clang/pop noise, like it has come ever so slightly off the chain ring's teeth, even though my chain line is perfect. Guess this is inevitable as the chain has way more room to jump around than with a proper tensioner-less single speed setup?

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20210501_165855

I just removed a chain link to tighten things up a bit and it has exacerbated the chain alignment issue, it's hard to get a photo but this looks terrible. The photo was taken with the camera squared up with rear hub and sprocket and you can see how far the chain kicks off to the right after its been through the tensioner so it has to do a big diagonal on its way to the front chainring. Surely that's not by design? I do have a brand new tensioner in my spares bag so maybe I'll try fitting that just to see if it makes any difference. 

 

 

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Posted (edited)

Actually, I've fixed mine. It seems my problems were two fold...

1. The old tensioner was definitely kicking off at an angle (old tensioner on the left):

20210501_171902

2. This is the funny one, one of my tensioner bracket mounting bolts was snapped off so the whole assembly had pivoted around the one bolt that was actually doing its job. The head of the bolt was still there so at a glance it looked ok but it just sheared off when I went to undo it:

20210501_170931

 

 

Here's the chain alignment after fitting a new bolt and the new tensioner, not perfect but much much better:

20210501_172108

 

 

 

 

Edited by Rip

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Posted (edited)

Oh, and the reason the old tensioner was kicking off at an angle was a worn out brass bush (8.1mm dia hole and a 7.5mm dia bush). That tension is 2-3 years old so I assume it's just worn out over time and thus the new one will as well at some point. Strange material choice IMO for that bush as these tensioners do not have to constantly rotate like a rear derailleur would for example because with a single speed setup the tensioner is always at a fixed angle. Literally any other material would have done as long as it wasn't soft like brass. Perfect example of potentially having to spend £25 on a new tensioner assembly because of a tiny inexpensive component. I might make a Phosphor Bronze bush for it. 

20210501_173827

 

 

Edited by Rip

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Posted (edited)

Anyone happen to know the recommended torque specs for the two bolts that mount the tensioner to the frame and also the single bolt that mounts the tensioner arm to the tensioner mount? All three bolts are M5 Stainless steel threading into aluminium so probably around 8Nm?

20210501_172108

 

 

 

Edited by Rip

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3 hours ago, Rip said:

Anyone happen to know the recommended torque specs for the two bolts that mount the tensioner to the frame and also the single bolt that mounts the tensioner arm to the tensioner mount? All three bolts are M5 Stainless steel threading into aluminium so probably around 8Nm?

20210501_172108

 

 

 

I don't know the exact Torque numbers for those 2 bolts but I don't tighten them too much as it doesn't take a lot of load.

I tighten mine to 8nm and that does the trick, never come loose. 

Rich 

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7 hours ago, Richie612 said:

I don't know the exact Torque numbers for those 2 bolts but I don't tighten them too much as it doesn't take a lot of load.

I tighten mine to 8nm and that does the trick, never come loose. 

Rich 

Thanks, my guess of 8Nm could be about right then. 

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On 5/2/2021 at 5:03 AM, Rip said:

Thanks, my guess of 8Nm could be about right then. 

 

20210503_114718.jpg

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Nice one, thanks. 

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