spectastic

should I add 2 more links? sram force short cage is rated for 28 cogs... if I add two more, I might get droopy chain on my lowest gear.. what do you think?

https://scontent-a-atl.xx.fbcdn.net/...90267872_o.jpg

Corben

My god you kids with your thousand speed bikes. Are you on the large chain ring or the small one. They'll want to know that.

e_guevara

Tip: When working with the RD, do not turn the bike upside down. The RD won't work properly (gravity is going against it).

As to your chain's length - it looks fine to me (I still think you should do that right side up). I assume it's on the big-big combo? As per Park Tool's guide, there should be an S-bend at the jockey wheels for a properly-sized chain.

See Park Tool Co. » ParkTool Blog » Chain Length Sizing

spectastic

ok i'll keep that in mind.

spectastic

it's the future. get wit it

spectastic

wacha think about my cable end?

trailangel

Here is a tip. Never turn bike upside down for any reason.
It'll ruin the brake cables.

How are you going to add 2 links? More like add new chain 2 links longer.

e_guevara

You shouldn't be doing your own wrenching...

spectastic

How does it ruin brake cables?

I do it all the time. Mainly tuning the Rd or taking off wheels to store bike in trunk or lubing the chain

DiabloScott

Nobody uses that gear anyway. Ride long and prosper.

trailangel

It's something nimrods do.

e_guevara

All the more reason NOT to turn your bike upside down when doing those.

chi-james

do sram derailleurs have a b-tension screw? if so you need to tighten it.

rydabent

chi

Sram RDs do indeed have a "B" screw, but it is NOT a tension screw like so many think it is. It is there to adj the distance between the jockey wheel and largest cog in the cluster. My Sram 7 calls for 6mm between the two. The easiest way to measure that clearance is with the end of a 6mm allen wrench.

spectastic

why can't you lube your chain with your bike upside down?

why can't you adjust your RD with your bike upside down? the indexing is lateral, what does gravity have anything to do with that?

why does it ruin your cables if you put your bike upside down? that one just doesn't make any sense.

FBinNY 

The chain length is fine, you KNOW that because the lower pulley still has room to swing upward. (Sram lower pulleys can swing above the lower loop even if it's dead straight, hence the big/big+1" minimum length).

No harm in working on bicycle upside down, the RD function isn't affected by gravity, and aero cable routing eliminates the damage to cables that used to be the issue.

However I wouldn't oil a chain with he bike upside down because dripping oil IS affected by gravity.

spectastic

is this what you're talking about??

e_guevara

Aside from the obvious purpose of the RD to shift cogs laterally, it also applies tension on the chain vertically (via the cage return spring) so it wraps around the cogs for proper teeth engagement. With the bike upside down, some of the tension is lost due gravity bearing down with the weight of the derailleur body and chain, resulting in poor shifting. The RD is not designed to be used upside down.

It's messier.

I lube my chain on the bottom run of the chain while backpedaling with the bike right side up. Any excess oil drips down on the floor after chasing the oil on the chain with a rag.

Backpedaling with the bike upside down causes the chain to chatter on the cogs due to insufficient tension.

I'll leave the last one to you.

trailangel

It's just the way it is. See rule #49 :
Velominati ? The Rules

cyccommute 

First, yes, your chain is too short. It might work but you risk damaging the derailer and dropout if you botch a shift. But you can't simply "add a couple of links" to a modern chain like you did in the past. The pins are peened so that the chain can take more side force to shift on a narrower chain. You can use a master link but you can't just push out the pin and push it back in again like you could in the old days. The chain will fail.

Second, although I don't turn my bike upside down to work on it, there is FBinNY is correct (mostly) about that. You won't damage the brake cable unless you have very old style brakes and even then it's not all that likely. The derailer will work just fine in any orientation you want to place it in since the mechanism is extremely light and the springs inside the derailer are very strong.

The tension on the cage return spring is strong enough and the derailer is light enough that gravity would only have a minimal effect on the derailer. There just isn't enough weight there to cause any kind of sag or loss of tension on the return spring. If the derailer were worn out or there was a problem with the spring, gravity might cause the derailer to sag under its own weight but in that case the derailer would have to be replaced anyway.

The rear derailer doesn't care if it is upside down or right side up. It simply doesn't matter.


You do realize that the chain goes around and around, don't you? If you put lubricant on the chain when it is at the bottom of the system and you turn the cranks (at any time) the oil on chain at the bottom will eventually become oil on the top of the chain. That's why gravity doesn't matter...sorry, but I have to disagree with you, FB, on that point but what's new? The oil (or any fluid) is going to flow within the chain and be distributed. If the bike sits for any appreciable amount of time, at least some of the oil is going to flow to the bottom of the chain. If you have it in excess, it's going to drip onto the floor and frame. It doesn't matter where you lubricate, it's going to flow.

And the bike clatters when you backpedal because the system isn't properly tuned. It will do that right-side up, up-side down or sideways.


Because you don't have an answer. Unless you have brakes like on the Fuji del Rey, it won't damage the cables to turn the bike upside down. Even then it's a stretch. It might damage the brake levers but any damage would only be cosmetic.

e_guevara

I will not argue with you on this one, and I do agree that modern (new) derailleurs have stronger return springs.

However, I have had an older bike with an old RD (probably worn) way back then that exhibited that problem. So as a general rule, for me at least, I do not service derailleur systems with the bike upside down.

You failed to understand my post completely. Lubing on the lower run with the bike right side up after chasing it with a rag minimizes the oil scatter than with the bike upside down. At most it will only drip onto the chainstay and probably the BB shell. With the bike upside down, it may drip on a lot more areas (saddle, seat tube, chainstay, seat stay).

Please stop assuming I'm an idiot.

I'm assuming the original poster of that comment (trailangel) is somewhat of a retro grouch from his history of previous posts, and therefore was referring to the old-style brakes. The OP did find the answer with the Fuji del Rey.

spectastic

that's the first I've heard of this... you're saying we can make chains shorter with the 10-11 speed stuff, but we can't add links? I can't imagine there to be too much side to side play with the chain unless someone is putting down 400 watts while shifting down 3 a climb.

woodcraft

Disagree. "Botching a shift"= chain riding on the tops of the teeth? That already happened to get into the gear.

- B screw should be tightened so there is clearance between the cog & jockey wheel.

- Cable should run straight through clamping washer/screw, not under bent washer tab. There is a groove in the washer for the cable.

- Cable housing loop looks short- enters the RD at an angle instead of smooth curve.

FBinNY 

Forgetting the side issues, the chain is long enough. The reason that the minimum length is bog/big +1" is so that you can hift into that combination without damaging anything. Well (assuming it's on the big chainring) you're in that combination with some spare slack and nothing happened. Therefore the chain is long enough.

OTOH- I prefer longer chains, subject to being short enough to loop the small/small without slack (which the OP said wasn't possible) Even if you cannot lengthen without causing small/small slack, you still have the OPTION of going longer if you wish, but why would you add even a minor problem if you don't have to.

There, also the issue of the chain itself. Lengthening would require adding 1 inner link and another connector. Not a problem if it's necessary or you choose to, but IMO an unnecessary expense.

cyccommute 

If you don't want to service your derailer upside down that is your choice. I probably wouldn't do it either but I have a workstand for that job at home. Out in the world, I wouldn't hesitate to turn the bike upside down.

However, just because you had an issue with an old rear derailer in the past that was worn out doesn't have any bearing on a new derailer.

Nope, understood you completely. But it doesn't matter. You shouldn't be putting on enough lubricant to get it all over the bike in the first place.

trailangel wasn't the original poster of that comment. spectastic was. trailangel's comment's are more in line with yours about turning the bike upside down. But you can't "ruin" the brake cables on a modern shifter/brake lever combination. There's nothing that sticks up above the handlebars to ruin. Since spectastic is the original poster and he is using a modern Sram derailer, I'm going to assume that he has the shifters to mate to it. So he has no cables that can be damaged...not that the old, old, old brake cables were that easy to damage in the first place.

No, you can't add links like you could with 6 or 7 speed chains. The side-to-side force on the chain doesn't come from the power you put into the drivetrain but from the movement of the derailer. You are forcing the chain from one cog to the next. As chains have narrowed, they have had to go to a peened pin to keep the side plates from pulling off. When you press out a pin, you destroy the peening and also increase the diameter of the hole in the side plate. You are more likely to make the side plate slide off the pin when you shift...the chain will break.

Modern chains use master links or they use the Shimano replacement pin. Personally, I prefer the master link because it's easier to install and remove.

Botching a shift can happen in any number of ways. If the chain is too short, you just don't have a lot of wiggle room.

Tightening the B-screw wouldn't do much since it would pull the derailer rearward. It's already stretched to the limit.

The cable is running where it should. I wouldn't wrap it around the post like that nor cut the inner cable that short but otherwise it's okay.

The cable housing loop is okay. A little longer wouldn't hurt but it's not the problem here.