New bike/BB90 trouble, please help!

Anonymous

Hi,

Ordered a new bike on-line, it's a Scott Addict R3, comes with Shimano 105, but have a arranged a deal with a fellow Bike Radar member to swap my new 105 with his new Rival. He kindly dropped the Rival off at the bike shop this morning so they could do the swap and then send me the bike. All fine.

Except it turns out the two BBs are different and neither is compatible with the Scott frame and Rival chainset.

The Scott frame needs a SRAM BB90 bottom braket, not the GXP style that comes with the SRAM Rival chainset. Trouble is the shop informs me they can't get one till August.

So my question is dose anyone know where I can get a suitable bottom bracket to fit a Scott Addict R3 and SRAM Rival chainset?

I have tried looking on Merlin and Googeling, but to be honest I really don't know what I'm looking for.

Please help.

markshaw77

This is a bit of a minefield, but having been through this with my Scott CR1, the options are fairly limited

Basically the standard BB in most top end Scott road bikes is the "shimano press-fit" standard (mostly referred to as BB86, but sometimes referred to as BB90 - not to be confused with the BB90 bottom brackets used in top end Treks )

Basically, the BB86 will only work with 24mm shimano-standard cranks (Shimano, FSA, Rotor). To run anything else (SRAM, Truativ, Campy) you need a different BB or an adapter

Have a look here for some more discussion:

http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=69716&start=0

it explains what the different standards are for each of the manufacturers/bikes, but the bottom line is that you can buy BBs/adapters that will fit in the "press-fit" BB shell of the Addict and allow the use of an SRAM (GXP) crank - they ain't cheap though and are very difficult to source in the UK at the moment (Have a look at the links in the discussion above or check out http://www.enduroforkseals.com)

IMHO, you are probably best off sticking with the 105 chainset and coming to some sort of agreement with the seller of the SRAM kit

Anonymous

Thanks for the reply Mark, just what I needed to know. (Though maybe not quite as good news as I'd hoped).

If you want to run Shimano you can fit the cranks straight to the frame with the bearings supplied with the frame.

If you want to run Sram you simply knock the Shimano cups out and fit a Sram BB86 press fit bracket in instead.

A 2nd option to use Sram is to leave the Shimano bracket in and buy a GXP conversion from Hope, which is an alu shim that presses into a standard shimano bearing so that you can run the GXP axle, whilst Shimano's axle is the same diameter along it's length the Sram one has a narrower outside diameter on the non drive side.

Having said that, the bit in bold here is pretty interesting.

A quick Google reveals this - http://www.chainreactioncycles.com/Models.aspx?ModelID=26899 (Merlin has them in stock).

Seems to good to be true, a cheap and simple solution?

Monty Dog

Yup, standard BB90 BB with Hope adaptor on NDS should be fine

Anonymous

Monty Dog wrote:

Yup, standard BB90 BB with Hope adaptor on NDS should be fine

Great, seems almost too simple. I've emailed the bike shop I'm dealing with to let them know. We'll see what they say.

rake

yes thats basically the same as gxp but 1mm wider to account for shimano bearings being 1mm thinner. just put 1 in each side of the left bearing. may have to tap them in or maybe not either way its no trouble.

Anonymous

rake wrote:

yes thats basically the same as gxp but 1mm wider to account for shimano bearings being 1mm thinner. just put 1 in each side of the left bearing. may have to tap them in or maybe not either way its no trouble.

To be honest this is a bit over my head, I'm very new to road bikes. But as long as that adapter allows be to use a GPX BB in my Scott frame I'm a happy bunny.

Anonymous

According to the bike shop I'm dealing with that spacer won't work/do what we need.

Not too bothered though as they've phoned round a few companies and found out that Shimano do a conversion kit that will allow me to keep the Dura Ace BB that's already in there and use the SRAM cranks.

This kit costs £6, and they're not even going to charge me for it.

Not sure the part number, but I can find out.

rake

RichardSwt wrote:

According to the bike shop I'm dealing with that spacer won't work/do what we need.

Not too bothered though as they've phoned round a few companies and found out that Shimano do a conversion kit that will allow me to keep the Dura Ace BB that's already in there and use the SRAM cranks.

This kit costs £6, and they're not even going to charge me for it.

Not sure the part number, but I can find out.

thats what the ones above do. those collars insert into your shimano bb so you can use sram cranks on it.
http://www.enduroforkseals.com/sitebuil ... _rwc_f.pdf
you can see more about it here. basically shimano cranks use 24mm diameter axles and so the inner hole of the bearings is 24mm.
sram is also 24mm except the piece at the end which goes through the left bearing is stepped down to 22mm, so you need a shim to reduce the bearing 24mm hole down to 22mm same as the axle end. why is it like this you may ask. its because sram clamps the left bearing to the axle between the 22mm step and the crank arm

Anonymous

rake wrote:

RichardSwt wrote:

According to the bike shop I'm dealing with that spacer won't work/do what we need.

Not too bothered though as they've phoned round a few companies and found out that Shimano do a conversion kit that will allow me to keep the Dura Ace BB that's already in there and use the SRAM cranks.

This kit costs £6, and they're not even going to charge me for it.

Not sure the part number, but I can find out.

thats what the ones above do. those collars insert into your shimano bb so you can use sram cranks on it.
http://www.enduroforkseals.com/sitebuil ... _rwc_f.pdf
you can see more about it here. basically shimano cranks use 24mm diameter axles and so the inner hole of the bearings is 24mm.
sram is also 24mm except the piece at the end which goes through the left bearing is stepped down to 22mm, so you need a shim to reduce the bearing 24mm hole down to 22mm same as the axle end. why is it like this you may ask. its because sram clamps the left bearing to the axle between the 22mm step and the crank arm

Are, right. I see what you mean. Looks like there the same as the Shimano kit the bike shops ordered. They said the Hope ones wouldn't work, looks like they got it wrong. As long as they get it working I'm happy.

maddog 2

Hope adaptors only work with Hope HT2 BBs. And Hope don't do a press-fit....

I run a Sram c/set (Red) on a BB86 frame (Giant TCR). I use the enduroforkseals press-fit cups, which are very well made.

See http://www.enduroforkseals.com/id258.html

They may not list a Sram version on the website but the do make one. Email them.

If the Scott really is a BB86 then this is a good option IMO.