Shimano XT crankset Upgrade

hbello

Hi All, if you want to replace a shimano XT m8000 1x11 for a carbon one sram or race face what would you pick? Consider I am looking for almost the exact geometry of cranks as we tried a few sram in a local bike shop and didn't fit in my bike and hit frame in left rear triangle.
My bike is a BMC Speedfox SF02 XT 2016. I don't even know if there is any change of the frame geometry between SF01 SF02 and SF03 more than materials.
Thanks for any advice

I am very interested in the Race Face Next but not sure if will work

The Rookie

Can you leave that question in just one thread? Decide which!

cooldad

I'd pick the Shimano, but surely with the correct BB most will fit? What's special about your bike?

hbello

I don't know what is special about my bike, only know that XTR and most SRAM crankset with Q factor 168 mm don't fit. They all hit same place in rear triangle left side.
HB

The Rookie

So you need a slightly wider q-factor crankset, some of the SRAM racey ones are quite narrow.

You need to measure up and then check the specs carefully before buying.

hbello

That is exactly why I went to local shop that at same time is a bmc dealer and they couldn't do anything in fitting sram cranks. Funny part is that for same bike model no XT version people fit sram race face etc....
I am looking for a carbon crank with very similar geometry that shimano XT which has a Q factor of 176 mm but get confused with some of the spindle lengths.
By the way local shop tried to contact BMC and they didn't answer and of course there is no other way to get help from them.
I am very happy with the XT cranks but kind of frustrated not been able to upgrade cranks if I want to.

The Rookie

It's not really a BMC issue, it's just finding cranks with the right width. Most of the SRAM carbon cranks are XC and won't fit normal boost rear end frames. Maybe have a look at DH cranks although the weight may be little different to some decent alloy.

Truvativ descendants have a Boost option so may suite.

hbello

I found the Race Face Next SL G4 covers multiple disciplines and has boost option as well, again I get confuse with the RF spindle code 134 vs 143. It looks like are the same arms with a different spindle. Q factor on those is 177 mm so 1 more than XT. I guess it should fit.

poah

I wouldn't swap it

hbello

Considering that option but frustrated with BMC and lack of information.

The Rookie

Not sure what you expect from BMC, you have a 12" rule, that is all you need!

You are asking BMC to assure you a certain crank from a third party will have the right Q-factor, why should they do that?

hbello

My only question to BMC was if there is any difference in geometry between same model bikes with different cranks configurations. Same bike (BMC Speedforx SF02) came with SRAM or SLX and mine that was the XT version cant fit anything. I think I have the right to know if my bike geometry is different or not to evaluate my options.

cooldad

They are not going to make different frames for different cranks. Trust me.

The Rookie

Agreed, not going to happen, what would be the point, they would just use the narrowest frame they may have made for all!

hbello

I saw the guys in bike shop taking out a xtr crankset from a Bmc speedfox 01 and it didn't fit my bike, SF01 has a rear triangle in carbon and mine is aluminum so I can see a chance to have other geometry there. The worst part for me was when the top technician told me he used to have same bike as mine with sram so we ordered and didn't work as well.

The Rookie

So the carbon rear triangle is different......so look at the alloy ones the same as yours.....yawn.

hbello

I did sir, my same frame (SF02) comes with SRAM X0, XT and SLX.
X0 has a Q factor 168.5 mm