Octalink & ISIS BB Tool Are They Both The Same?

Darkstalker420

Hi the chainguide on the youngest boys bike (in my opinion!) is pushing his chainline out of whack and somehow causing his bike to keep lunching rear mechs. (Second one croaked this morning) so i would like to remove the said guide and see if this helps. Alas i only have a square taper BB tool and i see the buggers have made the axle just SLIGHTLY to large for the BB tool :evil:. So i now have to get ANOTHER one...... Which looks near identical! (i love progress :roll:).

Just wanted to know if the Shimano Octalink BB tools are compatible with the ISIS BB tools (i'm not 100% sure what BB the bike has)...... Though i swear it said FSA on the drive side BB cup so to be honest i'm at a bit of a loss which to purchase (cranks are RPM's of some kind?).

Thanks.

YeehaaMcgee

If he keeps wrecking rear mechs, then in all probabilityt, the chain is too short, the mech hanger is bent, or the limit screws on the mech aren't set up properly.
Or all of the above.

supersonic

ISIS can be an external 8 notch tool. The internal type spline should be the same.

cooldad

But do you mean BB tool or crank puller?

Darkstalker420

Tool to remove BB. If i look at the chain from above (the chainring) it looks like the chain is trying to fall or be dragged off all the time towards the BB (worse when in the biggest cog at back). He has a single chainring (32) at the front and i would say it ACTS like the BB axle is to long (forcing the chain into "weird" angles). The only thing i can put this down to (without knowing the correct BB length) is the chain guide MAYBE is pushing the whole BB assembly out to the right a few mm (and forcing a less than ideal chainline).

The bike arrived from it's last owner as a single speed (but where we live this is borderline "insanity"). So i swapped the transmission from a donor bike and within hours it had torn off the mech hanger and destroyed mech #1!!! (the return spring for the mech had snapped so the cogs just hung there). This time it has happened when he lent the bike to a friend and once again the mech return spring is kaput and the mech is just hanging instead of tensioning the chain!!

When the bike is in the large cog at the rear WITHOUT the chain device attached by eye it appears to have about similar chain length (the mech is in about the same place) as mine in the same gear so i'm not sure if chain length is the cause however if you can show me a way to check if this COULD be the case i will of course check ....... As it's already emptied the spare parts box of rear mechs and now we have to go out and buy one.

Thanks.

YeehaaMcgee

Check chain length by routing the chain over the largest sprocket, and the largest chainring, without going through the rear mech at all, but DO include the chainguide...
Then add 2 whole links.
If it's too short, it will continuously trash the rear mech.
Even if there is a BB mounted chain device, it shouldn't cause the chain to drop into the BB - it sounds like you have a badly set up chainguide.
Pictures from a few different angles so we can see what's going on, please - and in the meantime, check that chain. I'm almost certain it's too short.

nicklouse

Tools to remove the bb can be the same or different tool to remove Isis and octalink cranks are the same.

But as to the issue it could be Chainline but ht will be incorrect bb for whatever cranks are fitted.

But if the rear mech spring is going then it is something very different.

But without knowing what th bike is. What the set up is etc who knows.

But chain length should be as above include ant chain device. But if a fully check with the sus fully compressed.

Darkstalker420

Bike is a Planet X Jack Flash (not sure of year) black powdercoat about 14" i will try to find the picture on Google again. Unfortunately the nipper while we were out on our bikes has converted it back to single speed :roll: and has now gone for a ride with his mate so i can really show you the issue now. We won't try to fit another rear mech until i have at least got the BB mounted chainguide off to see if it is pushing the BB/crank to far to the right. I will (when we put the gears back on perform the chain length test). So i will be safe then to order EITHER BB tool from CRC then? I have no trouble getting the cranks off with my extractor.

This is the frame (NOT his mind) don't know anything about it really infact when i emailed On One for a mech hanger they said they don't even have spares anymore We managed to get a Kona mech hanger to fit though.

viewtopic.php?p=16352546

Thanks.

nicklouse

Post pics of the set up as it is pointless looking any any other frame as that does not have the issues.

So what cranks?
What bb?
What bb width? Etc etc etc.

Darkstalker420

As i mentioned above bike is now single speed (again :roll:) so pictures of the mech etc ain't possible! Bike was second hand so i have NO idea what BB or what size because i need to purchase the correct BB tool to remove it (hence this thread). All i can tell you is the cranks have RPM written on them and they are spline BB other than that you know as much as i do!

Can't identify parts if i can't see them/didn't install/or purchase myself. The nipper has returned now so i will get some pics up as soon as poss.

Thanks.

Darkstalker420

BB shell is 68mm i have tried to get some shots of the BB/axle area. The chain device is pictured without the roller this would be pushing the chain onto the chainring usually but has been removed/used for the single speed kit at the back. Best i could do with the pics camera is crap tbh can't measure the BB axle as i don't have anything long enough (only a short metal ruler). If any more angles or pics of anything are needed do say so.

Thanks.

Darkstalker420

Another.

Thanks.

YeehaaMcgee

Look, since you CAN'T take the chain device off, but you CAN examine the chain length (without removing anything :roll: ) then check the chain length first.

Oh, and those shots show us NOTHING about the chainguide alignment.

nicklouse

Images not visible in Fire fox or on the iPad. So no idea.

Darkstalker420

Hi (sigh) . It's been one of those days today i can't even do that mate :roll: . In his haste to get out riding the nipper has put the other chain somewhere (the one used for the geared transmission) when he swapped BACK to the single speed kit that's on now which uses a DIFFERENT chain entirely (maybe longer maybe shorter etc!). So any measurements i tell you now won't mean jack (even if i had something long enough to measure a chain!) and as it's single speed i can't do the big cog/big ring add two links. it also won't be the same chain when the 8sp cassette and mech go back on.

And to top it off he ain't here so can't tell me where he put the chain :roll: *jesus wept*!! . As for the chain device how can i best get a shot that shows what you need to know? all i can say is the roller had plenty of play to slide to and fro as the gears changed didn't appear to snag anything and imho seemed to work as advertised. (although i have never ridden the bike bar a quick blast up the street). All the issues have been explained to me i've never seen the cause first hand. By the fact that it's doing in the mech springs i would say as other have mentioned that the chain is to short. BUT to see it even in the largest cog with the chain device there LOOKS to be more than enough chain. This has to be one of the most pain in the arse problems i have ever seen on any of the bikes i've looked after imho and the fact it's eaten through my supply of rear mechs and now we have to go buy one maybe for it to "lunch" that one to if it was mine i would BEAT IT with a hammer .

Not sure whats up with the pics tbh i have Firefox and can see them??

Thanks.

YeehaaMcgee

The roller will do precisely ZERO to keep the chain in line at the top of the chainring. We need pictures of the upper chainguide, side on, fromt view, top view, rear view - so we can see that it's aligned properly with the chainring.
The roller isn't a guide, it's just there to stop the slack from the mech whipping about from unseating the chain from the chainring.

Darkstalker420

There is no upper guide just a bolt/seat tube bracket to anchor the lower guide. I can get a pic if you need to see what i mean. The lower roller is the ONLY chain guide.

Thanks.

YeehaaMcgee

It's not a chain guide then.
Get one.

Darkstalker420

Like this.

Thanks.

YeehaaMcgee

Looks to me like the chainguide is missing.

Darkstalker420

ah ha (never used one like that myself so wasn't sure what it looks like from new). It came from the last owner like that so i figured it was "working" as is :roll:. Will look into replacing the top bit if possible (or the nipper will LMAO!). One other thing i noticed when i took the crank off to cure an annoying creek is there are small silver washers between the crank and the BB spline (you can see them in the pic). Are these spacer used to adjust the chainline or are they just what they appear (washers).

Thanks.

YeehaaMcgee

I can't see which washers you're on about.

right. So... if you want to keep it as a geared setup, then you're going to need some kind of chain device. The simplest, and most commonly available one is just a front mech, with the limit screws set so that the mech keeps the chain on.
You can ditch that thing that's on there now, but that may mean the BB won't fit properly.
I'm rusty on how the old style BBs measured up, so I'll let Nicklouse handle that one.

nicklouse

The washers are not removable they are the stops for the cranks.

Darkstalker420

He definitely wants gears but only at the rear. If the downhills wern't uphill round here i would say stay single speed tbh but some sort of gears are a must .

Thanks for the help if i had hair it would be all over the floor by now LOL!

EDIT cheers Nick i won't mess with them.

Thanks.