chain rub

[David Ross]

I built up a Gus recently. I used a 1x11 Deore derailleur and the chain rubs the tire in the largest cog. The chain above the chain stay clears the tire, but below the chain stay the chain rubs the tire. Is my problem 1x11 cassettes with 135 spacing? I'm only running 2.25 tires and the Gus is rated up to 2.6. Any help would be much appreciated. 

[Steve]

David, would a wider bottom bracket axle solve the issue?  How long is the current one?

[Patrick Moore]

First, check chainline.

Doesn't the Gus have typical long Rivendell stays? This should structurally minimize the chance of such chain rub, so perhaps your spindle is too short for proper chainline. Does Riv spec a spindle length for that frame and a 1X11?

OTOH, if the chainline is correct but you still need to add another couple of mm to the drive side spindle for the chain to clear the tire, perhaps adding a 1 or 2 mm spacer behind the DS cup will fix things, chainline be damned.

IMO chain clearance is more important than a perfect line. To paraphrase what Grant said years and years ago when someone fretted that slighly imperfect chainline might accelerate chain and sprocket wear, "If you are riding enough to replace chains and cogs more frequently than you think you should, then you are lucky to be riding so much." And modern chains do tolerate a lot of deflection without greatly affecting performance or wear.

-

[Mike Rossi]

For the record, I’m using a 122.5 mm spindle on my Susie with a 1 mm spacer added to the drive side. It gives plenty of clearance with 2.3’s. I am using a 2 x 7 setup, so my biggest sprocket is a little further away from center, but I think I could still clear the tire even if it were closer. If I were using 2.6’s with a 11 speed cassette, I’d probably get the Shimano bb that has a 123 mm spindle with a 2.5 mm spacer on the drive side. I wouldn’t think there would be a chain rub issue with that setup.

Sent from my iPhone

On Jul 6, 2024, at 11:23 PM, Patrick Moore <bert...@gmail.com> wrote:



--
You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bun...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/CALuTfgvaybQC2hmhjyEihLbqapf7SOU1_zWht6KLKetL8OZCgw%40mail.gmail.com.

[Mike Rossi]

Also, you mentioned chain rubbing at the bottom and not the top. When I received my frameset I had to adjust the derailleur hanger as it was misaligned. That may be an issue as well.

Sent from my iPhone

On Jul 7, 2024, at 4:49 AM, Mike Rossi <mwill...@gmail.com> wrote:

For the record, I’m using a 122.5 mm spindle on my Susie with a 1 mm spacer added to the drive side. It gives plenty of clearance with 2.3’s. I am using a 2 x 7 setup, so my biggest sprocket is a little further away from center, but I think I could still clear the tire even if it were closer. If I were using 2.6’s with a 11 speed cassette, I’d probably get the Shimano bb that has a 123 mm spindle with a 2.5 mm spacer on the drive side. I wouldn’t think there would be a chain rub issue with that setup.

[Steve]

What Mike Rossi said!  That would explain the peculiar situation of the chain rub at the bottom only. 

My money is on Mike.    

[Will Boericke]

It wasn't until I got a hanger alignment tool that I realized how many bikes have misaligned hangers.  I use it all the time!  And newer drivetrains are definitely much more sensitive to misalignment.  All to say, this sounds like an alignment issue to me as well

Will

[Mike Rossi]

Yes, Will, it’s one of my favorite tools. I have a feeling there are quite a few Riv owners with friction shifters riding around with hangers that are misaligned. But, I suppose that can be seen as an added benefit to friction shifting.

Sent from my iPhone

On Jul 7, 2024, at 10:48 AM, Will Boericke <wboe...@gmail.com> wrote:

It wasn't until I got a hanger alignment tool that I realized how many bikes have misaligned hangers.  I use it all the time!  And newer drivetrains are definitely much more sensitive to misalignment.  All to say, this sounds like an alignment issue to me as well

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/6f6e3179-87de-48b1-b1b7-4b050bb74fabn%40googlegroups.com.

[Patrick Moore]

The bent hanger suggestion is a very good one and responds to the fact that the rub is only on the lower chain run. I'll be interested to hear what Mike finds, and I wonder how many of my own der hangers have been slightly bent but hidden by friction shifting.