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Hi
Trying to help out a friend who is on a budget.
Currently he has a ruined Truvativ Powerspline 68x118mm bottom bracket and worn rings that need replacing. One crank arm has also worked loose a few times, meaning it may need replacing anyway.
I have a new octalink crankset that I said he could have.
Is it a straight swap as long as it's a 68x118mm octalink bb. The only thing I dont know is if its Italian or english thread on the truvativ.
Anything else to be aware off?
Cheers
Is it a straight swap as long as it’s a 68x118mm octalink bb
The chainset will determine the bb length, not the frame
The only thing I dont know is if its Italian or english thread on the truvativ.
Measure the frame. If it is Italian thread then the bb shell will be 70mm wide. If it is BS thread then it will be 68 or 73mm wide.
The frame from the bottom is 68mm
Thanks
I did remove the bottom bracket and it said 68mm shell on it.
The octalink chainset is FC-M410
Should be a 118mm bb for that chainset...
Many thanks guys.
Just to clear it up. Whatever chainset you have determines what bb you need.
In this case it will be a 68x118.
So for this bike it will always be a 68x?? Depending on what chainset you get.
Do I have that right?
So for this bike it will always be a 68x?? Depending on what chainset you get.
Yes (although with modern chainsets the axle is now part of the chainset rather than the bb)
Cheers
The saga continues. I forgot the fact he has a double setup so he said he would buy one instead.
Currently he has a SRAM VIA Centro power spline, 48/32T chainset and a
SRAM, PG-1030, 10-SPD, 11-36T
He said he only uses the 48t ring. He does not use the 32t. It's a Boardman Hybrid bike.
He has a 10 mile exercise route he does on a daily basis. Nice flat tarmac cycle route.
Ideally if he could lose the 32t and go for a single that would suit him better.
If he has to stick to a double he doesn't mind.
What are his options in replacing the chainset and bottom bracket.
From reading square taper seems to be the most reliable.
Any recommendations?
Recommend keep it double incase he wants to go up a big hill one day something like a Shimano Tiagra 50-34 chainset with an uberbike bottom bracket. https://www.uberbikecomponents.com/category/401/Bottom-Brackets
The hollowtech 2 system is much lighter, stiffer and easier to put together/maintain compared to square taper.
So a road chainset would work?
Everyting i have been reading suggests it can be one but you get issues with q factor? chainstay clearence etc. Mind you they were all discussion about mountain bikes, i take it Hybrids are a bit different.
Good point, I forgot it was a hybrid.
The Shimano Road cranks run a spindle 5mm shorter than the MTB cranks.
The chainrings etc are all 2.5mm closer to the centreline of the bike, probably not a problem especially if he likes using the big chainring while running the lower gears on the rear cassette, but it is worth checking the existing inside chainring and crankarm clearances.
Otherwise, it is generally more difficult getting MTB cranks that have larger chainrings.
For the Shimano hollowtech II MTB cranks the BB is intended to be installed directly into 73mm wide shell or with 2.5mm spacers either side for a 68mm shell, the road crank is intended to be used without spacers for 68mm shell width only.
Many thanks