lerouc Posted October 10, 2016 Share I was helping a buddy replacing his chainrings on his crank yesterday when i noticed that his crank turns a lot easier than mine. Obviously without the chain on just spinning it around. When you spin his his turns a couple of times before coming to a stop spinning where mine is a lot more "tight" if you spin it it almost immediately comes to a stop. He has an alu bergamont with external BB and deore cranks and i have an alu anthem with internal BB with XT crank. I have recently removed my crank, checked my bearings and everything seemed fine, added a little bit of new grease and put it back and tightened it. Logic tells me that i would have to use a bit more power to turn my cranks than what he would use with his cranks? Could it be that my BB is stuffed, did i tighten my crank too much? Link to comment Share on other sites More sharing options...
NINER_boy Posted October 10, 2016 Share Crank spacing is incorrect, so the crank "binds" on the bearings. Remove some spacers and tighten to spec. Check for play, Ad / remove (depending if it still binds or there is play) some spacers and tighten to torque spec. Repeat until no play between crank en BB bearings AdamA 1 Link to comment Share on other sites More sharing options...
lerouc Posted October 10, 2016 Share Crank spacing is incorrect, so the crank "binds" on the bearings. Remove some spacers and tighten to spec.Check for play,Ad / remove (depending if it still binds or there is play) some spacers and tighten to torque spec. Repeat until no play between crank en BB bearings Not at the bike right now but from what i can remember there isn't any spacers. Link to comment Share on other sites More sharing options...
ALLMTB Posted October 10, 2016 Share As far as I know, shimano cranks don't make use of spacer on the crank/spindle between the crank and BB. The BB could possibly have spacers between the BB and frame but this should not have any effect on rotation. Remove the crank and make double sure the bearings are spinning smoothly. Check that the sleeve between the BB cups inside the frame is properly aligned and not damaged. On my gf's previous bike the LBS installed the pressfit BB, but the sleeve was miss-aligned while doing, this caused the sleeve to break. The result was that the broken edges of the sleeve then pierced the bearing seal from the inside and some pieces of plastic got lodged in the bearing causing it to seize. The cranks turned but on the inner bearing race, the bearing itself did not rotate. Also, when installing the crank again, take note not to over tighten the preload cap. BDF, AdamA and JXV 3 Link to comment Share on other sites More sharing options...
JXV Posted October 10, 2016 Share I was helping a buddy replacing his chainrings on his crank yesterday when i noticed that his crank turns a lot easier than mine. Obviously without the chain on just spinning it around. When you spin his his turns a couple of times before coming to a stop spinning where mine is a lot more "tight" if you spin it it almost immediately comes to a stop. He has an alu bergamont with external BB and deore cranks and i have an alu anthem with internal BB with XT crank. I have recently removed my crank, checked my bearings and everything seemed fine, added a little bit of new grease and put it back and tightened it. Logic tells me that i would have to use a bit more power to turn my cranks than what he would use with his cranks? Could it be that my BB is stuffed, did i tighten my crank too much?Presume both are 24mm Shimano cranks. The external threaded Shimano BBs come with spacer rings and instructions for placing them depending whether the bike's BB shell is 68mm or 73mm wide and whether BB mounted chain guides, chain case or front derailler is to be fitted. This should all result in the correct external BB width (92mm iirc?) being obtained. Then when you attach the left crank arm, it is pre-loaded using a small handheld (metal or plastic) socket that has a very low torque setting. You need literally just enough torque to snug the thin o-rings on the inner faces of the crank arms onto the rotating plastic face of the BB. Your BB may run with more friction if the crank arms are preloaded too tightly or if the bearings are damaged or if the grease under the BB seal needs to be replenished. There should not really be any major friction difference between threaded or press fit BBs provided both were correctly installed. It is most likely your bearings are just on their way out. One of my BB70 bearings got stiff recently after 2.5 years of use - root cause was water damage - be careful when you wash your bike. Sent from my SM-G935F using Tapatalk Rudi Pollard and BDF 2 Link to comment Share on other sites More sharing options...
lerouc Posted October 11, 2016 Share Ja no spacers that i could see. Link to comment Share on other sites More sharing options...
lerouc Posted October 11, 2016 Share Presume both are 24mm Shimano cranks. The external threaded Shimano BBs come with spacer rings and instructions for placing them depending whether the bike's BB shell is 68mm or 73mm wide and whether BB mounted chain guides, chain case or front derailler is to be fitted. This should all result in the correct external BB width (92mm iirc?) being obtained. Then when you attach the left crank arm, it is pre-loaded using a small handheld (metal or plastic) socket that has a very low torque setting. You need literally just enough torque to snug the thin o-rings on the inner faces of the crank arms onto the rotating plastic face of the BB. Your BB may run with more friction if the crank arms are preloaded too tightly or if the bearings are damaged or if the grease under the BB seal needs to be replenished. There should not really be any major friction difference between threaded or press fit BBs provided both were correctly installed. It is most likely your bearings are just on their way out. One of my BB70 bearings got stiff recently after 2.5 years of use - root cause was water damage - be careful when you wash your bike. Sent from my SM-G935F using Tapatalk Thanks for the advice, found some videos on youtube that also say it could be the side cap on the left arm that might be the culprit, I will loosen it tonight and check. Thanks. Link to comment Share on other sites More sharing options...
lerouc Posted October 11, 2016 Share Thanks everyone, it was the side cap that was on tooooooo tight, loosened it and it spins alot better now. Thanks!!! andydude and Hairy 2 Link to comment Share on other sites More sharing options...
BaGearA Posted October 11, 2016 Share Types of bearing and brand off BB also play a huge part In my Experience, Shimano my crank spins pretty okay. Put A Raceface BB(turbince X-type) on the other day and with one one firm push my crank turned 9 times Link to comment Share on other sites More sharing options...
lerouc Posted October 12, 2016 Share Types of bearing and brand off BB also play a huge part In my Experience, Shimano my crank spins pretty okay. Put A Raceface BB(turbince X-type) on the other day and with one one firm push my crank turned 9 times Ja but price difference... Link to comment Share on other sites More sharing options...
Guest Posted October 12, 2016 Share Is it just me but why does my BB left hand bearing always fail first? Link to comment Share on other sites More sharing options...
JA-Q001 Posted October 12, 2016 Share Ok, 2 things. 1st - New grease is always more sticky, grease has to "wear in", most of the time it will take a few rides to settle in. So if you regrease your bb and not your friends, then it will look more "stiff". 2nd - New bearings are also "stiffer" than old bearings, it also wears in. A bearing is only worn out when it developes play or if it gets "rough". Rust or a lack of grease contributes to this. The preload can have a small effect, but youll have to rape that little tool to overdo it really. Thats why the original shimano tool is such a small disc, it limits the amount a normal person can tighten it. Link to comment Share on other sites More sharing options...
NotSoBigBen Posted October 12, 2016 Share Is it just me but why does my BB left hand bearing always fail first? And mine demmit, I surmise cause it's so open and the right hand one has a bit of 'protection from the crank shape and blades? I could of course be totally wrong .... Link to comment Share on other sites More sharing options...
JXV Posted October 12, 2016 Share Ja but price difference........and grease and sealing. The Shimano BBs come packed full of that clear luminous green grease of theirs. It is water resistant and quite a bit thicker than most aftermarket bike greases so it does not disperse very quickly. Its when the grease runs out or gets dirty that the problems start. I reckon BB bearings would last a lot longer if they had grease ports and could be injected with a shot of grease from time to time. BB doesn't rotate as fast as wheels do unless you're in granny gear so a bit of grease drag has very little effect...maybe fractions of a watt but it makes the bearing run longer before it gets tight. Sent from my SM-G935F using Tapatalk Link to comment Share on other sites More sharing options...
Guest Posted October 12, 2016 Share And mine demmit, I surmise cause it's so open and the right hand one has a bit of 'protection from the crank shape and blades? I could of course be totally wrong ....I thought it might be because I always get on my bike from the left side. I stand on the pedal and swing my body over, this puts pressure on the left hand crank every time. Maybe I should spend the rest of the year getting on from the other side as I've just replaced the BB. If the right side fails first then I know. Myth buster in the making NotSoBigBen and lerouc 2 Link to comment Share on other sites More sharing options...
koukie Posted October 12, 2016 Share Thanks everyone, it was the side cap that was on tooooooo tight, loosened it and it spins alot better now. Thanks!!!Now you can deduct at least 30min off your previous race times! lerouc 1 Link to comment Share on other sites More sharing options...
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