V20 Bottom Bracket

V

vosadrian

Guru
Hey All,

I swapped the crankset on my V20 on the weekend. While I was at it, I noticed the drive side bearing is pretty crunchy and seems to be on the way out so I want to replace it. Has anyone got the full spec for the V20 Bottom bracket? I believe it is a SRAM GXP, but not sure what thread etc. This was on a 2020 V20 builtup bike from Cruzbike... so whatever CB supplies as standard would be fine.

Incidently, I installed a BBK 155mm crankset (GXP) with 52/36 rings. So shorter crank arms and longer gearing. I have not ridden it yet, but hoping the shorter crank allows for more consistent power and perhaps a small amount of aero benefit while also allowing to spin quicker.... and combined with a couple more teeth on the big ring, should allow me to pedal out to 60kph or so. Not useful for flat roads (where I was fine pedalling to about 50kph with the old setup).... but I do run out of cadence sometimes pedalling down some long 2-3% declines near me.

Cheers!
 
Don1

Don1

Guru
yep Matt is right. otherwise BSA, english thread. sram in there wisdom don't do GPX anymore they've moved onto DUB which is their own standard 29.8mm axle. you can buy BB to suit BSA, press fit blah,blah to suit the cranks..... so if you have GPX cranks you need a GPX axle centres and a BB with BSA threads. anyways, smaller cranks do strange things, you can spin at a higher cadence but your actual leg speed is actually slower.... the slower leg speed allows you time to deliver more power but you need more gears..... you can gpx BB from aliexpress ....https://www.aliexpress.com/item/400...f6-5&pdp_ext_f={"sku_id":"10000001113546512"}
 
V

vosadrian

Guru
Thanks Don, I prefer to order local at the moment rather than wait for something from Aliexpress. On ebay there are a number of SRAM and aftermarket BB options from cheap options from brands like GUN and J&L for ceramic bearings for <UA$40 delivered to SRAM branded stuff for around AU$50 delivered to some Australian made ceramic (HSC, AITA) for $170-200 to Ceramic speed for AU$500.

I don;t really want to spend the $500 for Ceramic speed. I am leaning towards the SRAM branded standard bearings, but are the unbranded presumably chinese ceramic bearing versions as good as the higher priced stuff from HSC etc? I normally shy around from ceramic bearings thinking that the power loss is so miniscule it is not worth the extra... but if costs the same, are the cheap options better than standard SRAM branded stuff.... and is the mid priced ceramic bearing worth it over the cheaper ceramic bearing stuff?
 
V

vosadrian

Guru
Thanks Craig,

I've always been a fan of OEM... mostly shimano for me but that is not an option with the crankset I have now. Unfortunately the SRAM BB I have that came with the bike and has around 6000kms does not feel smooth on the drive side, so it has not lasted well. But I may give another a go.

Cheers!
 
jond

jond

Zen MBB Master
Vossi I’d imagine hope a local bike shop would have a gpx bottom bracket. Yep ceramic bearings are mostly just ceramic balls on a metal race offering nothing for mere mortals other than bling. It’s crazy but some of my easiest spinning cranksets were square taper jobs. I guess the sealed bearings of cup bearings are a liability for those of us who ride in the rain. You cannot beat bsa threaded though for quiet reliability and ease of service though.

see you Saturday. I don’t have a spare sram bb unfortunately. Got a shimano Durace spare new too in the box.

my vendetta runs an fsa crankset. Supposedly compatible with a shimano bb or not. Lol. It’s getting hard to find a bb threaded fsa ........ lucky I don’t ride in the rain then
 
V

vosadrian

Guru
No rush at the moment. It is just something I noticed with the crank out. Crank in and spinning with no chain it feels fine and spins OK... not 30 seconds like some youtube videos of ceramics... but it seems to go for 3-5 seconds like I expect normally and I can't feel any issue. Its just one of those things that I know it is not ideal so I want to replace it sometime.... before 12+12 as I need all the help I can get!
 
Drcoop95

Drcoop95

New Member
Has anyone noted increased resistance to the bottom bracket when the cinch bolts are tightened down on the front stays around the bottom bracket cups on a V20, (gray/ black version)? Also how to correct this problem. I’m using a Dura Ace 7800 BB. Thanks
Marshall
 
Robert Holler

Robert Holler

Administrator
Staff member
Those old stays that went around the cups... sigh.

You might have to change stays or use a different BB. The reality is that some cups are too thin to be clamped and you will have to be extremely ginger in tightening.
 
B

Beano

Well-Known Member
Don1 said:
shouldn't be that tight jusr 4Nm or so max... review cruzbikes videos re building up s40-v20.
Click to expand...

2NM for me, did used to do 4nm but had some clamps crack.

My way of doing to now is to tighten the clamp bolts down whilst holding two credit cards in between. Once the clamps bite onto the cards, gingerly go around the each bolt tightening a quarter turn at a time until you reach the required torque of 2nm.
 
A

Apollo

Well-Known Member
Don1 said:
they tell us (hambini et al) say ceramic is useless on bikes since ceramic bearings pnly come into their own above 10000 rpm..... so you pays yer money.......
Click to expand...
Yeah, the average rider or mere mortal would be lucky to eek out a watt advantage on a ceramic BB vs standard metal bearings. One thing about ceramic, there's no substitute for the smoothness of those bearings. I've ridden on ceramic hub bearings and a BB for a while, which were well used not new, and let me tell you those ceramic products were far smoother than anything I've ever tried straight from the store shelf. Standard bearings don't compete compared to the boutique brand ceramic equivalents in smoothness even if the performance advantage is actually negligible. If I had the money, I'd replace all the bearings on my bikes to ceramic just to have that feel on my rides. It was transforming. Who knows, maybe it's worth more than a watt from the placebo effect alone.
 
A

Apollo

Well-Known Member
Beano said:
2NM for me, did used to do 4nm but had some clamps crack.

My way of doing to now is to tighten the clamp bolts down whilst holding two credit cards in between. Once the clamps bite onto the cards, gingerly go around the each bolt tightening a quarter turn at a time until you reach the required torque of 2nm.
Click to expand...
Thank you for this post. I was going to be researching the force required to clamp the stays on the BB shell because I'm going to be swapping out for shorter stays on my bike and need this information. You saved me some time. Good thing I invested in a torque wrench with a big range in adjustment. 2NM is a lot less than I'd have guessed.
 
D

Duncanleon

New Member
You might want to look at ChrisKing Bottom brackets. They can be a bit pricy but will outlast and outspin a ceramic BB. I've had both. I had to replace the ceramic after 2 years but that was because of the the roads in Au. The Steel bearings of the ChrisKing on that DF and now on my V20 are still going strong.

Im told that it's also a "name dropper" for tech afficionados if that matters.

Some of their higher end BBs have a lifetime warranty and advertise that it will outlast the bike it all depends on how much you want to spend
 
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