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Hi,
I need to choose a new bottom bracket for my Heckler that will work with some SLX cranks.
The information from Santa Cruz that I've had says that it is a 68mm English thread and can have a chain line of 47.5 and 50 mm.
How does this translate into axle length?
Thanks for any help,
Martin
With slx cranks, you don't really get any say in the chain line. Just get any HTII bottom bracket that fits your budget. An slx one would work perfectly. The come with spacers. Have a look at shimano tech documents for exactly where they go. Good luck.
I'd be thinking more about longevity. The Shimano HTII BBs don't have a great reputation for sealing or long life. I have a Wheels Industry BB in my spares box waiting for my Shimano to wear out. Hope is also popular on here. The mag just finished a 2 year test on the Chris King BB - it's still going strong, but it's rather expensive.
With HT2 bottom brackets, you don't need to worry about chain line, it can't be adjusted, as the axle is part of the chainset. Any set of HT2 BB cups will fit. As it's a 68mm shell, you will need to fit the spacers that are included, (not needed for a 73mm shell), but other than that there is nothing to adjust.
So your options are- cheap shimano cups, but expect to have to replace them periodically, expensive "better" ones like hope or king, which need to last 3-4 times longer than shimano to justify the expense in terms of function, but may be worth it on pose value, or others such as those from superstar which are probably somewhere in between.
I have one bike with SLX running fine after 18 months, and hope ceramic on another which is another year older and still fine.
Obviously it all depends how often and how far they are ridden. I clearly aren't riding enough or I'd have killed that SLX bottom bracket by now!
You pays your money and takes your choice
So if I understand this right, when I take the SLX crankset off my old bike I take the axle out of there and put it onto the new bike which I have fitted the external cups to?
Sorry for the noob questions!
Yes that is correct. It's a 2 piece chainset. The axle is part of the drive side crank. You need a couple of special tools to fit the new BB cups which I guess you need to budget for also. Have a look on the Park tools website for info. It's not a difficult job at all.
there is basically 3 shimano HTII BBs for mountain bikes: Deore (worse sealing and heaviest), LX/SLX/XT - all the same and then XTR which seems to be the same again but in black.
Rose bikes have the LX/SLX/XT for £13 and the XTR for £16 - £3 sounds about right for the mark up of a less mass produced colour option rather than any mechanical differences. Even the weights are the same.
I would go for the LX/SLX/XT one and if you kill it quickly consider getting a more expensive one or just fit it with Enduro bearings.
It will come with 3 plastic spacers. For 69mm with BB shell you normally run one on the non-drive side and 2 on the drive side (where the chainrings are).
For a 73mm shell you just fit one to the drive side.
You should normally get the frame faced before fitting but it depends on frame - eg carbon ones should come perfect and you don't want to cut the carbon with a facing tool!
Use a bit of anti-seize or teflon grease on the threads when fitting.
Remember to use the plastic pre-load bolt on the non-drive side to preload the bearings before you righten the clamps on the crank arm and look at the guide on how to remove as there is a little plastic part inside the clamp of the crank arm.
PS you can use your existing BB if it is still fine and you have the correct spacers.