HT2 BB and single ring set up question
Is it ok to fit the BB without any of the plastic 2.5mm spacers? SS set up.
Reason for asking is that after taking off the outer and inner rings from a new LX M580 crankset, to leave just the middle 32t ring fitted to the inside of the ‘spider’ tabs, the chainline is measuring about 51/52mm and with my very basic 2 spacer SS hub kit, the rear cog is about 10mm inside the line of the front ring.
My current thinking is to remove the two DS spacers at the front, plus possibly the one on the NDS and get/fit a rear hub spacer kit that has a range of spacer widths that will allow the front to line up the rear cog.
Is it ok to fit and use the BB with no spacers? Can’t seem to find any say so on tech docs, but I am a boy, so looking isn’t a strong point 🙂
TIAPosted 3 years agocpSubscriber
And yes, one way or another you need to run all the spacers on the bb. Assuming you have a 68mm shell as your using all three spacers at the mo, then removing spacers would mean the cranks don’t touch the bearings.
You can swap spacers from right to left, but you need to use them all.Posted 3 years ago
Cheers cp, yep, tis a 68mm shell.
So I presume if I were running this as a triple, I’d put two spacers on the NDS and one on the DS to get the correct chainline?
Gotcha with the multiple spacers, VeloSolo do some very nice colours but was baulking a bit at £15 inc postage, so bought a basic conversion set locally. Buy cheap, buy twice as they say 😉Posted 3 years agowwaswasSubscriber
Keep the BB spacers and play with the back end.
aren’t the two rear spacers different widths – can you swap them roudn to move the cog further out?
If you have any old Deore type cassettes the spacers on the those (once you grind the rivets holding the cassette together off) are quite good for fine tuning chain line.Posted 3 years ago
Yep, thanks www, the two rear spacers are 20mm and 15mm and there is a very thin metal washer too. Not too sure where the metal washer is meant to go tbh, so positioned it on the outboard side of the cog before the 15mm spacer.
I’ve got the larger 20mm spacer fitted on the inboard side of the cog, positioning the cog as far outboard as it can with these two spacers and with the two BB spacers fitted to the DS of the cranks, I am surprised to see the rear cog still needing to move out 10mm for it to line up with the front ring – was more as I originally fitted the middle ring on the outside of the spider tabs as most guides seem to suggest.
It is a 68mm shell. Presumably it’ll be okay to have two BB spacers on the NDS, with one on the DS?
It is a 2006 frame, so wondering if it would work better with a sq taper BB with an appropriate length axle?Posted 3 years agotheotherjonvSubscriber
There are 3 spacers with a HTII, each 2.5mm. Two are needed (one each side) if you have a 68mm shell width, to space it out to 73mm which is the other BB shell size (for threaded type BB’s, let’s ignore oddities and push fits for now). 68 + 2*2.5 = 73.
The cranks are sized for 73mm so as above if you leave the spacers out then they’ll have 5mm of side to side play and won’t load the bearings.
The third spacer is needed with both 68 and 73mm, and is there to use up the space that an e-type mech fitting would take. If you have an E-type mech then you don’t need this third spacer.
So in your case, with no mech and a 68mm shell you need all three.
Where you put the spacers is up to you – you can tune chainline a bit with them, but only in 2.5mm steps, and if you move from the 2DS / 1NDS then your cranks will not be equidistant either side of the BB shell. Whether you’d notice 2.5mm or even 5mm on an mtb is a moot point though. Just be aware if you move the cranks inbound on the DS by moving spacers to the NDS that you don’t run into clearances issues with granny tabs, etc.Posted 3 years agowwaswasSubscriber
I’d just play around with hub spacers and keep the BB setup with 2 DS and one NDS spacer.
Most of my SS cogs have ended up fairly far across towards the drop out.
I’ve always thought it might be a good thing to have the load as close to the end of the axle as possible, tbh, but no idea if there’s any scientific basis for that.Posted 3 years ago
Great stuff, thank you both.
Nicely explained jonv, I’m with you. No issues with clearance as it’s a 32t single ring SS set up and as it is atm with the 2 BB spacers on the DS, there’s about 10mm between the ring and chainstay.
It just seems strange that with the 32t middle ring in the same position as it would be as a triple chainset, it has a chain line dimension of 51mm, rather than the 48.5mm defacto standard (coincidental 2.5mm difference?).
As for inboard/outboard position of the rear cog, my thinking so far has been that it might be better closer to the hub flange, rather than the end of the axle, but like you wwaswas, no scientific reasoning or knowledge to back that up!Posted 3 years agoYakSubscriber
Yup – as above, use all 3 bb spacers and I’d not try and use them to adjust chainline. Instead use spacers on the rear hub to gain the missing mm’s.
If you’ve got lots of old bb spacers, then you can use them as freehub spacers combined with one of the big spacers you already have. They are slightly too big, but if locked in tight enough with the locknut, do the job. Edit – use a metal one from an old cassette next to the locknut as it bridges the difference in size between the plastic spacers and the locknut.
You will give in to the allure of something nice from velosolo eventually though 😉Posted 3 years ago
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