11-32 on Tiagra RD4600 mech

chrisaonabike

Disclaimer: I've read the spec and I know that 32T is more than the RD4600 supports!

That said, I've found a few people on the interwebz saying they've done it and it works, so I thought I'd try it, as the cassette was only 22.50 at Wiggle when I looked the other day.

So I tried it, and it's not bad... just a couple of questions (in bold below) I'd be grateful for some advice on...

- It's slightly noisy in the lowest gear (Front - 34, rear 32) - not all that surprisingly as the chain does run pretty close to the sprocket as it goes round the jockey wheel. I tried tightening the B-screw (two whole turns) but the mech didn't seem to move away significantly. Why would that be?

- When I fitted the chain I removed a couple of links to make it exactly the same length as the old chain, which I was using with an Ultegra 12-30 cassette. Would I be better off taking only one link out, or no links out, now that I've got the 11-32 on?

The shifting itself is fine - indexing is just as good as with the old 12-30 cassette.

Grateful for any advice!

gazza1286

Any B-screw adjustment should be done with the mech slackened on the hanger. The movement will be minimal but should be noticeable when adjusting with the chain on the largest sprocket.

The 'add a link or not' advice relies on an assumption that the original length was the correct length. Measuring around big - big + 2 links always seem to work for me.

chrisaonabike

Thanks for this. Why does the mech need to be slackened? I've watched several videos on the B-screw, but they don't refer to slackening the mech first.

Could you elaborate on the method of figuring out the right chain length, I'm not clear on that. Thanks!

wotnoshoeseh

ChrisAOnABike wrote:

Thanks for this. Why does the mech need to be slackened? I've watched several videos on the B-screw, but they don't refer to slackening the mech first.

Could you elaborate on the method of figuring out the right chain length, I'm not clear on that. Thanks!

https://www.youtube.com/watch?v=Vg2SoOOrpE8

bobones

If the chain is not slack (sagging down) in small-small and not super tight in big-big (chain makes an S shape through derailleur cage) then it's fine. If the chain is a bit slack in small-small you can use the B-tension screw to tighten it. You'll probably notice the effect of the B tension screw more in small-small than anywhere else.

chrisaonabike

bobones wrote:

If the chain is not slack (sagging down) in small-small and not super tight in big-big (chain makes an S shape through derailleur cage) then it's fine. If the chain is a bit slack in small-small you can use the B-tension screw to tighten it. You'll probably notice the effect of the B tension screw more in small-small than anywhere else.

Well this is the thing. It's not slack at all.. but it is pretty tight in big-big. It's only rubbing slightly round the jockey wheel and generating a little extra noise.

Would a chain with an extra link or two help?

bobones

If it's beyond spec then it might never be totally smooth. You can check the chain length a few ways, but if it's too short you can usually see just by looking at it. See image here https://www.parktool.com/blog/repair-he ... -section-4

If you have a quick link lying around, you can use it to easily see the effect of an extra link. However, lengthening the chain usually involves buying a new chain.

Stanley the 2nd

I ran Dura Ace 9000 a couple of years ago and ran a 11-32 and 11-30 cassette no problem on a few occasions. Considering it's the shot cage pro derailleur I was impressed that it worked okay.

Bumo_b

You can actually run a 34t rear cassette on the long cage. I have done it on the 4600 and currently doing it on the 4700. Chain length is critical though and you need the tiniest bit of slack taken up in the "small/small", literally the quarter of a turn that does it is enough.
Use this
http://www.machinehead-software.co.uk/b ... hcalc.html
Silent as any other combo
PS In case you are wondering, I cant climb for toffee, but can spin like a madman

chrisaonabike

Update:

Ok, so now that I've got my chain routed through the jockey wheels properly, I've been out with the 11-32, and it's now quiet and shifts well. It's a bit noisy when cross-chaining, but obviously I'll avoid that.

However, one time only, as I shifted on to the 32T cog, the chain went too far and fell into the spokes as if the limit screw was adjusted wrong. However, this never happened with the 11-30, I've never moved the limit screws, and the indexing has been perfect for almost five years.

I couldn't make it happen again, and once the chain was on the 32T, pushing the shift lever didn't move the derailleur at all.

Is it possible that somehow the chain is shifting up the cogs with a bit more oomph (obviously it's a bit tighter round the 32 than the old 30), and had the momentum to go too far?

Should I ease off the limit screw a bit anyway?

Bumo_b

Personally I have found that each change of cassette requires a marginal adjustment as there are always very slight intolerance's, maybe how they sit on the hub or spacer, but someone with far more intelligence than me would be able to give you a more definitive answer!

bobones

The limit screws don't affect the indexing: they only set the outer limit of movement of the derailleur. The best way to set these limits is to remove the cable from the fixing bolt so it's not affected by cable tension, and push/release the derailleur by hand. If you can't move the chain past the last sprocket by hand then it won't go over when you've got the cable attached.

svetty

If it's over-shifted once it will do so again. Just adjust the limit screw a smidgen so it still shifts............