Well, that was embarassing...

[Robert O]

So, I ordered my V20 frameset last fall, then waited until December for that batch of frames to roll in. Of course, by the time that the frame got to Rose City Recumbent Cycles, I had a whole family room worth of cool parts off of eBay. I got the frame home at about 6:30 PM that Saturday, and by just after midnight I had everything but the last 5 links of 11-speed chain set up.

Problem was, I couldn't get the ceramic BB to behave. I'd torque down my Red crank until there wasn't any play in the splines, but then it was too tight on the BB. If I set it up so the BB was right, there was play in the crank because the non-drive arm wasn't fully engaging the bottom of the splines. Not a lot of play, mind you, but I knew it was there.

Finally, I'd had it. Yesterday I pulled the BB, threw on a GXP BB that I had hanging around. Reassembled the front triangle, and there was no play. Still wasn't the slickest crank, but it was at least tight. I went to put the ceramic BB away; served me right for buying a no-name, right? Then I noticed that there were spacing rings on the cups. In my haste to put the bike together, I'd never seen them. I never took the front end apart far enough to notice. I pulled the whole thing apart again, and put the ceramic BB back on. Tightened it all up (minus the spacers), and the whole thing fit like a dream.

Still, it was just a couple of wasted watts, right? So I'm riding back down the valley this afternoon, enjoying the nice smooth rotation of the pedals. I pulled a DF rider for a couple of miles while we chatted. As we rode through Kent, we had to put up with a few roads crossing the trail. At the last road crossing, he told me that he figured that with no interruptions for a couple of miles, this was where I was going to drop him. I told him that you never know.

Next thing I know, I'm hauling 32 mph on level ground, no sweat. That's always been a 26-28 mph stretch, and I'd always feel pretty good about that speed. Now, I'm eclipsing that. And this isn't a sprint, it's just cruising speed. I looked back over the forum when I got home, and noticed that Ratz rated BB as the second largest speed differentiating component next to wheels. Man knows things!

 

[DavidCH]

It's embarrassing to admit it. I have a ceramic BB that I haven't fitted because I thought perhaps I might upgrade to a V20 and if I did I probably change cranks to SRAM. Now after reading that, I will definitely have to fit it.

Guess you would call it resistance training.

 

[ratz]

Robert we've all been there.

When you pedal you create Watts; you can have those Watts go to Heat, Flex, or Speed. Your BB is the fulcrum and it directly controls the amount going to Heat and Flex.

I don't know things; I just read what the smart guys write and repeat it here so I don't have to store it inside the brain cage. Pre-Recumbent I just was the nob that let the bike shop rip me off for half knowledge. After catching recumbent N+1 disease it wasn't affordable to not know this stuff. I have learned from others more than I've taught; think of me as a aggregator that sometimes can remember and credit the person that I learned it from. When I forget to create someone just assume it wasn't intentional. And you all get credit for reading through my typos. If I had to edit properly then I'd get ¼ the info posted.

Any how, bearings need to spin....We all do the "good enough" trap now and then; I just made powerTap replace the wife's pedals because the bearings feel Gritty and I was very insistent that they do it on warranty because they are expensive; yet I have been riding all season on a rear wheel with crushed bearings (over tightened the skewer) simply because i have never ordered a replacement before wheel bearing before. So an $8 fix probably slowing me down far far more than her pedal was going to affect her. I measure urgency by expense instead of affect.. And now because of this thread I get I better get off my butt and get that replacement ordered before the Iowa TT.

Now for all the rest; really seriously 4 things and 1 optional.
1) Don't over tighten you chain stay clamps you'll crush your BB Bearings.. Hand Tight and back off ¼ turn
2) Each season end or beginning take your BB off the bike and clean it; it's holding forces on these bikes that the Bearing cups were not designed to carry. Even John T admitted it was "naughty"
3) If the bearing don't spin silky smooth then replace it with a new $30 part -or- buy the $150-199 one so that it will last for 5+ seasons.
4) IF you have a cheap BB and you thing you might have crushed it; take an afternoon to take the crank apart and check if it rotates gritty in your fingers. If it is get another $30 and tighten it correctly

Optional
4) Start saving now for the new chain-stay that's going to eventually arrive that eliminates the cup clamping; and cross your fingers that Jacob makes it backwards compatible. That will be worth 1 mph as it stiffens up the front triangle

(BB discussion only affects the S and V series bikes)

 

[LarryOz]

Optional
4) Start saving now for the new chain-stay that's going to eventually arrive that eliminates the cup clamping; and cross your fingers that Jacob makes it backwards compatible. That will be worth 1 mph as it stiffens up the front triangle

Seriously Bob - 1mph?? Wow - can't wait to get that upgrade!

 

[ratz]

Seriously Bob - 1mph?? Wow - can't wait to get that upgrade!

IF you already have the XD-15 it's probably more like .25-.50 mph; but yeah if you think about how much force is getting loaded and unloaded on to the bearing cups each rotation of the pedals it's a lot. Ages ago I measure it on the Kickr. SRAM 30$ versus XD-15 and played with over tightened clamps (I had an old BB to sacrifice.); I compared the Stages power reading versus the kickr wheel reading for the same Erg setting the delta of the power loss between the crank and wheel, was not nominal when I altered anything that affected flex or rotate of the spindle. If we can get that load off the cups; it's going to make a difference. This would be about the time I made the BB spin video; That's actually the 2 BB I was comparing. Sadly that's before we started being diligent on recording the data in spreadsheets.... Heck at that time we were using a Quest to train on the trainers most of the time.

Edit: Not this is not a linear speed increase; this is going to apply to high power loads call it > 225 watts; below that you are not pushing hard enough to make a different. This is part of the reason Robert O didn't notice the BB issue until he hit sprint speeds. Doesn't matter when you are just putting along at 100 watts.

 

[Robert O]

IF you already have the XD-15 it's probably more like .25-.50 mph; but yeah if you think about how much force is getting loaded and unloaded on to the bearing cups each rotation of the pedals it's a lot. Ages ago I measure it on the Kickr. SRAM 30$ versus XD-15 and played with over tightened clamps (I had an old BB to sacrifice.); I compared the Stages power reading versus the kickr wheel reading for the same Erg setting the delta of the power loss between the crank and wheel, was not nominal when I altered anything that affected flex or rotate of the spindle. If we can get that load off the cups; it's going to make a difference. This would be about the time I made the BB spin video; That's actually the 2 BB I was comparing. Sadly that's before we started being diligent on recording the data in spreadsheets.... Heck at that time we were using a Quest to train on the trainers most of the time.

Edit: Not this is not a linear speed increase; this is going to apply to high power loads call it > 225 watts; below that you are not pushing hard enough to make a different. This is part of the reason Robert O didn't notice the BB issue until he hit sprint speeds. Doesn't matter when you are just putting along at 100 watts.

Thanks, Ratz. Bearings seem to be fine; it wasn't the rings I was tightening, it was the crank bolt. I didn't notice the BB issue, until I wasn't working against it anymore, but now I can feel it even in the just cruising mode. Can't wait for next year's STP...

By the way, you're a heck of an aggregator; I have this vision that whenever someone types a Cruzbike related search term into their browser, it diverts straight to your head. You make great use of the stuff you soak in, thanks!

 

[Lief]

Uh oh - I've begun to learn stuff.
I actually followed that conversation.

Better start working on my N+1 psychology training.

 

[Tohopko]

New chainstay???