Sram Red cranks and BB30A Bottombracket.

Discuss light weight issues concerning road bikes & parts.
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TLN
Posts: 217
Joined: Wed Jul 12, 2017 4:50 pm

by TLN

Hi all.

Trying to swap crankset with spider to integrated one. Both are BB30/PF30.
Old crankset set up with gray lockring spacer on NDR, big (10-12mm) spacer on DR side.
Integrated crankest comes with lockring spacer on NDR side, with no spacer on DR side and is also shorter.
At first, I was a bit scared: axle is way longer then existing one. After reading forums I figured out that it's not too bad:
In order to install crankset with integrated spider I'll need to remove grey lockring from NDR side, and replace it with wavy washer and some shims. And after all it will be same q-factor and everything as with my existing set up.
Does this sounds like a plan?
I guess I need to get this kit: https://www.amazon.com/gp/product/B0050 ... 1DF1&psc=1
I might have wave washer somewhere btw.

Thanks.
His: Specialiez S-Works Tarmac SL5 Disc.
Hers: Cannondale Synapse HM Disc

alcatraz
Posts: 2538
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Sure the old crank isn't bb386? Sounds like it could be.

The current bb might not support bb30 if it's designed for bb386 (long spindles). If the cups/bearings are internal with no portrusions outside the frame I think it should work with the existing bb.

In any case a sram red crank (w. int. spider) should work with a bb/pf30a frame so feel free to buy it.

by Weenie


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Beaver
Posts: 777
Joined: Wed Aug 18, 2004 6:06 pm

by Beaver

If it's about this bike, your old crank had a bb386 axle and the replacement will work as planned. You will also increase bearing life by doing so. ;)

Image

TLN
Posts: 217
Joined: Wed Jul 12, 2017 4:50 pm

by TLN

alcatraz wrote:
Wed Nov 20, 2019 8:05 am
Sure the old crank isn't bb386? Sounds like it could be.

The current bb might not support bb30 if it's designed for bb386 (long spindles). If the cups/bearings are internal with no portrusions outside the frame I think it should work with the existing bb.

In any case a sram red crank (w. int. spider) should work with a bb/pf30a frame so feel free to buy it.
Yeah, it sounds like my old crank is BB386. I thought newer Sram RED cranks come in only on BB30 and GXP versions.

I've just installed crankset with integrated spider without lockring. Worked great. Still need to get wavy washer and spacers, but it will be delivered in a few days.
Beaver wrote:
Wed Nov 20, 2019 10:07 am
If it's about this bike, your old crank had a bb386 axle and the replacement will work as planned. You will also increase bearing life by doing so. ;)
Speakign of bearings, why's that? Because we eliminate lever by using shorter spindle?

PS. Weight savings:
1. Spindle comparsions:
20191120_095423.jpg
2. BB386 crank vs BB30 crank
249gm vs 178gm
20191120_095508.jpg
20191120_095455.jpg
3. Chainrings.
Metal spider, 53/39, 172.5mm length vs integrated spider, 52/38, 175mm length
440gm vs 358gm. Actually former crank required spacer on drive side.
20191120_095537.jpg
20191120_095527.jpg
4. Complete weight, former crank without spacer that adds 8-10gm:
538 vs 694gm.
20191120_095652.jpg
20191120_095713.jpg
So it's almost 160gm lighter, looks better and will increase bearing life. Sounds like a win to me
His: Specialiez S-Works Tarmac SL5 Disc.
Hers: Cannondale Synapse HM Disc

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Beaver
Posts: 777
Joined: Wed Aug 18, 2004 6:06 pm

by Beaver

TLN wrote:
Wed Nov 20, 2019 5:24 pm
Speakign of bearings, why's that? Because we eliminate lever by using shorter spindle?
Yes, angular contact bearings may help here but they also have a little more drag. A matching frame/crank combo is just the best.

And you may shave another 20g later, when you switch to Praxis Works chainrings (shifting quality and durability are equal).

TLN
Posts: 217
Joined: Wed Jul 12, 2017 4:50 pm

by TLN

Beaver wrote:
Thu Nov 21, 2019 4:08 pm
TLN wrote:
Wed Nov 20, 2019 5:24 pm
Speakign of bearings, why's that? Because we eliminate lever by using shorter spindle?
Yes, angular contact bearings may help here but they also have a little more drag. A matching frame/crank combo is just the best.

And you may shave another 20g later, when you switch to Praxis Works chainrings (shifting quality and durability are equal).
I don't think I'll bother about 20gm honestly.

Now the biggest question, is what was my previuous crankset? BB386? I got 5mm lockring on NDS, BB73 bracket in Synapse 2018 and 13 or 15mm spacer on drive side.
His: Specialiez S-Works Tarmac SL5 Disc.
Hers: Cannondale Synapse HM Disc

by Weenie



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