Transmission database - for all your crank / bb / bottom bracket questions

Yarp: the quoted chainline is centred between the two rings.

Sheldon also writes that typically, Shimano double rings are spaced 5mm apart: so as I wrote above "With the correct BB, the inner ring will have a chainline of 41mm and the outer, 46mm."

If you're happy using the inner position, 1mm shouldn't be a problem as long as you don't use a bushed chain.

For the moment the inside is fine. Its just for my commute bike. I can live with 1mm out. Won't notice probably. Thanks for the help. Much appreciated

So today I tried to install my Stronglight 49D crankset onto my frame. I had a 111,5 TA314 axle which would give me a 42mm chainline. But after placing the axle into the frame and putting the crankset onto the frame I ran into some problems. The chainring was hitting the frame, I also had a Stronglight 118mm axle. This worked fine, but now i'm dealing with a 44,5 or 45mm chainline. Are there any track hubs with more threading so you could put a spacer in it, On the pictures I have added you can see the clearance I have with the 118mm axle. There is not much room left, so a shorter axle won't do I guess.

3 Attachments

Just a thought: is the axle asymmetric? Are the pedal ends of the arms equal distances away from the chain stays (see third photo).

In the second photo, the NDS looks a long way off the BB, compared to the DS. The chainring bolts nearly overlap the BB shell which suggests something is wrong to me.

Perhaps the axle is the wrong way around...

But to answer your question: I don't know of any hubs with extra thread.

I'm running a 45mm chainline: you need to re-space the hub (to get your chainline), then re-dish the wheel.

The axle is in fact asymmetric, I put the longer end of the axle at the DS. So it should be allright, I think.

Ah re-space the hub! Just found out that Goldtec hubs are 45mm spaced

The axle is in fact asymmetric, I put the longer end of the axle at the DS. So it should be allright, I think.

What's the OLD of the frame?

The 49d is pretty old (no pun intended), so intended for a 120mm frame?

I have 120mm in the rear, it could be true that it not was intended for a 120mm.
Here is some more information about the specific Stronglight cranksets.
http://www.classiclightweights.co.uk/components/stronglight-timeline-comp.html

But either way, my problems could be solved if I have a hub which is spaced at 45mm chainline right? Or try to lift up the difference with spacers?

Tom ritchey superlogic ISO bb in 110 + sugino 75 = 42 mm

Hell of a lot cheaper than a centaur bb. £10 ATM on ebay.

Having a complete ball ache replacing my drivetrain. After buying a Sugino RD2 set up, and it not working out, I just went and bought a proper track chainset - Campag Record Pista. I did have some trouble removing the bottom bracket I had in from the Sugino set up and had to take it to a shop. The threads looked fine when I got it back, although not even sure if they actually checked it.

Anyway, I also decided to get the Record BB since it is recommended (which I am now doubting). The bottom bracket goes in nice and smoothly and I can hand screw right up almost to the end. Then I see it’s misaligned about 0.5mm. Ok, that’s not much, but when I tighten it with the tool, the spindle doesn’t spin well. You can feel friction with the bearings. I don’t want this with a new £55 BB.

Cleaned the shell with a rag and toothbrush numerous times. Cleaned the BB of any gunk on the threads. Installed and uninstalled a few times. No dice.

First time I’ve encounter this misalignment installing one. So, is it likely to be the threads on the shell? Or perhaps the bottom bracket itself?

Anyone have any experience / ideas with this? Fed up taking the frame to London bike shops to get a shafting.

Thanks.

What do you mean by "misaligned": what isn't lined up with what?

Photo?

I uninstalled it all, but have done a sketch to hopefully better explain.

I doesn't screw in straight! That's a better description than "misaligned".

(so that diagram is looking directly up / down on the BB shell)

And sorry, its the drive side in case its not clear from the sketch...

Hm that's strange. Do you have an old BB lying around to test if that goes in straight? As you don't want to go to a shop.

Yeah, I do have an old BB, but old is what it is and the threads are not clean! I'll try and clean them up and test it. It may confirm which threads are off.

I could always take it back to the shop that removed the old BB for me. They charged me enough for it!

Heh!

Perhaps the new BB is somehow off, unlikely but...who knows. Bring it too I guess?

Question: Novatec + fixiesupermarket store (e-bay) seems to give a 40ish chainline...not 42.
Are there any (preferably) cheap cogs than sit 2 mm to the right?

I've ordered a spacer, but more than 1 mm is not possible as that's all that's left with lockring on. So that may not resolve it properly.

Gotcha!

Either the shell needs to be faced or the threads need to be re-cut.

If when you install the BB there is an equal and opposite gap on the NDS, then the shell is off. This shouldn't present you with any problems unless you are using an external BB, as the cups are independent and wouldn't be parallel with each other.

However, from what you wrote originally I think the shell is threaded on the DS. This means the NDS and DS cups don't screw in parallel to each other and when you tighten them up the axle needs to bend to fit in cups. Obviously it can't so it binds the bearings.

Thanks.

I was afraid that the frame shell may need some repairs. It must have happened removing the stuck bottom bracket that was in before. From memory, it went in fine and was sitting square.

The other bit you've described, kind of makes sense. Although in my last attempts, I only installed the DS and when tightened to a point, the spindle stopped spinning smoothly. Probably because that little 0.5mm threw the angle out a fair bit over the length of the shell.

I have also read about folk installing the DS and NDS simultaneously to try and align it. Although believe this is not recommended!

I have a 2015 Cannondale Supersix Evo Hi-Mod frame. and a set of Rotor 3DF cranks with a 30mm axle. It seems like there is lots of conflicting information around what bottom bracket I need, particularly between PF30 and BB30.

Is anyone able to recommend a bottom bracket for me? It'd be a bonus if anyone could also let me know what tools I need to install it.

I have also read about folk installing the DS and NDS simultaneously to try and align it. Although believe this is not recommended!

I can't imagine that will do anything but make the situation worse.

Swapped out my BB this morning as I noticed a (visual) wobble as it went round on the NDS arm, couldn't feel it wobbling under foot as it was tight on there.. After taking it off saw that the spindle had been twisted out of shape. On the commute in couldn't believe the difference the new bb made, felt like a completely different bike! Has this happened to anyone before??

Fixie skidder?

2x8 speed! No skidding for me :)