Author Topic: XM Carbon Speed - "Gran Tourismo" Frameset  (Read 3079 times)

Sakizashi

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #15 on: May 28, 2025, 09:50:07 PM »
There are several advantages to internal routing, additional design flexibility with asymmetric designs, etc, which makes T47 attractive. I think the benefits created by having a larger tube are mainly limited to the construction of metal frames and lugged carbon, which is where the T47 originated. It's just a threaded version of PF30.

IME, the bearing size stuff is marginal to the point of being nonsense if the bearing is well sealed. Most people in shops seem to believe that SRAM-branded dub BBs have great longevity, and those that use tiny bearings. Those opposed either claim that they are wearing through a lot of BBs, regardless of size (i.e., something is wrong with the bike or the installer), or are just discussing theory. Long-winded way of saying that the BB standard used wouldn't prevent me from buying a frame.

That said, if you made me king for a day, I would decree that all bikes use T47 or some variant thereof to get us down to 2 types of cups, 1 standard bearing size, and a bunch of reducers. I am not really opposed to BSA either, but realistically, the weight difference is marginal. It's around 20g in a carbon frame, including the BB, and about 50g on a Ti frame.

This XMcarbonspeed frame looks excellent IMO. Geo isn't my cup of tea; nevertheless, I'm looking forward to seeing it built up.
« Last Edit: May 28, 2025, 09:51:58 PM by Sakizashi »

Serge_K

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #16 on: May 29, 2025, 03:48:16 AM »
Looks very nice, thank you for posting!
Could you please add a few pictures of the inside of the frame? Curious to see the weave around the BB & headset.
Also, would you mind adding a few pics of the downtube, the side facing the wind? And the headtube? Curious to play Jesse Coyle to assess aero-nessitude :D

Sorry to hear about your leg, hope you'll be back riding a bike soon!
Fast on the flat. And nowhere else.

Daviddavieboy

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #17 on: May 30, 2025, 04:32:50 AM »
Bigger bearings = Long lasting.

 Yet on 2 bikes with less than 1000 kms on either I had to replace both T47 SRAM DUB BBs both for chewing up bearings. To be fair one was on a gravel bike (internal bearing) that not treated very nicely. The road bike (external bearing) developed a rough spot that did go away when washing out the NDS bearing - I still changed it out though. Moral of story - buy quality bearings if T47 is a MUST. FWIW
I have a hope until someone can prove otherwise.

Da11as

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #18 on: May 31, 2025, 04:10:25 AM »
Yet on 2 bikes with less than 1000 kms on either I had to replace both T47 SRAM DUB BBs both for chewing up bearings. To be fair one was on a gravel bike (internal bearing) that not treated very nicely. The road bike (external bearing) developed a rough spot that did go away when washing out the NDS bearing - I still changed it out though. Moral of story - buy quality bearings if T47 is a MUST. FWIW
As I mentioned in CS-R01 thread, avoid SRAM BBs entirely. Since they introduced DUB standard all bearings are exactly same tiny bearings regardless of BB shell. They wear out super quickly if you ride anything that is always dry and not dusty. Consider them only if you are not particularly strong or heavy rider, as they start to deform at power output of ~250W.

In general, I recommend NOT to use DUB/30MM axle in anything smaller than BB30 BB shell
« Last Edit: May 31, 2025, 04:19:53 AM by Da11as »

Daviddavieboy

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #19 on: May 31, 2025, 05:21:56 AM »
  They wear out super quickly if you ride anything that is always dry and not dusty.

  Consider them only if you are not particularly strong or heavy rider, as they start to deform at power output of ~250W.

  In general, I recommend NOT to use DUB/30MM axle in anything smaller than BB30 BB shell

 "They wear out super quickly if you ride anything that is always dry and not dusty." - I had the opposite experience, in the wet they wore out faster.

 "In general, I recommend NOT to use DUB/30MM axle in anything smaller than BB30 BB shell" - I would even argue that DUB should be avoided altogether unless a person plans on using top quality bearings.

 "Consider them only if you are not particularly strong or heavy rider, as they start to deform at power output of ~250W." - From personal experience I def agree with this. I had a SuperSix from 2014-2018 (BB30 using a Shimano DA crank) that went through MANY sets of bearings until I installed a Praxis BB and now the same experience with two T47. Even still, at 1100W sprint I can hear and feel a creak and 2 days ago a 60 mile zone 2 gravel ride it was dead silent the whole time.


I have a hope until someone can prove otherwise.

Da11as

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #20 on: May 31, 2025, 06:06:34 AM »
"They wear out super quickly if you ride anything that is always dry and not dusty." - I had the opposite experience, in the wet they wore out faster.
Oh well, I meant "unless you ride...". Should have checked what I wrote ::)

rsw42

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #21 on: June 02, 2025, 10:38:24 AM »
So here are some pictures of the head tube... I'm really not good on taking these pictures - any advice how to take them will be welcome

rsw42

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #22 on: June 02, 2025, 10:41:55 AM »
BB Area...

And a little update on the build... will be coated with cerakote and gun candy chameleon effect thingy... but will take some weeks...

Groupset: GRX 1x11

Daviddavieboy

Re: XM Carbon Speed - "Gran Tourismo" Frameset
« Reply #23 on: June 02, 2025, 03:32:39 PM »
BB Area...

And a little update on the build... will be coated with cerakote and gun candy chameleon effect thingy... but will take some weeks...

Groupset: GRX 1x11

 I wish they still made the exterior in a 'weave' Everyone seems to be making their frames UD carbon. Probably saves weight I suppose.
I have a hope until someone can prove otherwise.