Alfine won't fit. Thoughts please

[Gillstay]

Hi. This is a 45 tooth crank that fits into a 68mm wide bottom bracket. It has a 6 mm plastic spacer from the frame it came out of.

When I fit it in this one it ends up just touching the frame. Can I space it any more.

Or am I best going for a smaller chainwheel and putting a bigger sprocket on the 8 speed nexus hub in the back wheel. Thoughts please.

 

[Gillstay]

Hollowtech bearings I forgot to mention but you probably worked out.

 

[Cycleops]

So you're putting it in a different frame. The Alfine chain ring is touching the stay? If that's the case it sounds like the offset on the chainwheel is not enough to clear the stay.
A smaller chainwheel is needed or one with more offset.
Those spacers are just to give a bit of end float.
You might try washers under the retaining bolts or can you reverse the ring to give more offset?
I suspect the frame wasn't intended for hub gear use.

 

[Sharky]

Or am I best going for a smaller chainwheel and putting a bigger sprocket

You'll need a smaller, not bigger sprocket to give the same gear.

Another option, take off the outer chain guard (whatever its called) and put the 45 on the outer side of the spider. You might need shorter chain ring bolts or with the right thickness of washers, still be able to bolt on the chain guard. So everything is on the outer side of the spider.

Good luck

 

[Tigerbiten]

I'd put crank and hub in the frame and check how straight the chainline is.
At a guess, if the chainring is touching the chainstay then it's not in line with the sprocket.
Once you know how offset inwards the chainring is then you will have a better idea how to fix it, spacer washers vs moving the chainring.

Luck ............

 

[Gillstay]

ooh! Yes that might work. I see what your all on about now. It might be enough. Will report back soon. Many thanks.

 

[Gillstay]

Well tried it with the guard off and the ring on the other side.

So that has created enough room. Just need washers for the studs that hold the chainring on and a smaller spacer for the crank as the original one is now too thick.
On the hub, can I run the sprocket the other way around ? This would then make the chain run perfect.

 

[Sharky]

You can get a set of bolts for a single chain ring for not much. Better than fiddling with extra spacer washers.

Don't think you can turn the rear sprocket round as it will have a flange that keeps it away from the hub. If you reverse it, it will not give clearance for the chain.

Don't worry too much about the chain line. There should be enough tolerance in the chain to make it work.

 

[Gillstay]

Yes, I suppose as its only 1 cm out it its well with in its normal working range

 

[Pale Rider]

Rohloff sprockets can be reversed to double their life or keep you going while crossing the Andes or whatever adventurous Rohloff owners do.

I'm all but certain Shimano hub gear sprockets are not reversible.

 

[GuyBoden]

With a Hollowtech BB, spacers can be used before the threaded cups to get the correct chainline/spacing, I did this the other week.
https://www.cyclechat.net/threads/c...llowtech2-chainset.276118/page-3#post-6589610

See the spacers below:

 

[Ming the Merciless]

 

[GuyBoden]

View attachment 620342

Yes, exactly, you can also use 1.25mm spacers not only the 2.5mm spacers provided with the BB, these can give a more accurate chain alignment.

See my post from another thread:

Eventually, I managed to get a reasonably good chainline on my roadbike using a Hollowtech MTB chainset and BB by using one 1.25mm spacer on the non-drive side and two 2.5mm spacers plus one 1.25mm spacer on the drive side.

 

[si_c]

It looks to me like you're fitting a 73mm axle chainset to a 68mm bottom bracket, which is why spacers are needed. Hollowtech comes in two formats 68mm and 73mm with the latter being for MTB equipment. Alfine being one of the trekking groupsets falls between this and the spacers allow it to fit to either, but you still have to account for the correct chainlines. The correct solution is as posted above by @GuyBoden and to use a set of spacers to correctly position the cranks.

If set correctly you should be able to use the chainguard.

 

[Gillstay]

It looks to me like you're fitting a 73mm axle chainset to a 68mm bottom bracket, which is why spacers are needed. Hollowtech comes in two formats 68mm and 73mm with the latter being for MTB equipment. Alfine being one of the trekking groupsets falls between this and the spacers allow it to fit to either, but you still have to account for the correct chainlines. The correct solution is as posted above by @GuyBoden and to use a set of spacers to correctly position the cranks.

If set correctly you should be able to use the chainguard.

I had come to very close to the same conclusion and very nice to have it verified as i can do it with much more confidence now. Thank you all.

si-c I still cannot get the chainguard on but am not concerned about the fact. It would need 15mm worth of spacers on the drive side to fit the frame. i think the frame is meant to be for a triple chainset or a smaller chainwheel, but at the moment i need to use as many of the bits I have from the old frame as possible as the costs keep mounting. Thank again all.