[MENTION=104655]jimc101[/MENTION] thanks for the suggestions. Timed on strava was almost identical. I had minor adjustments made to saddle height and had a smaller stem fitted. Also pumped up tyres... All had a positive effect, but none alleviated the problem. I only use the 52 cog on my Trek so it's not low gearing comparisons.
[MENTION=2667]Homebrew[/MENTION] I tested the standing starts on both bikes on as similar a gearing as I could get. The BMC requires more force through my legs to get moving irrespective of gearing.
[MENTION=252435]RubeRad[/MENTION] the BMC wheels spin much more freely than the trek. It's not even comparable. The brakes rub on the Trek so it's lucky if it does 3 full rotations.
[MENTION=345109]corrado33[/MENTION] I cycle in London dude. It is dangerous to not be able to pull away at traffic lights easily. I'm having to use a gear so low to move off that after two turns I'm changing up.
[MENTION=193959]FastJake[/MENTION] I have tested the bikes back to back (see above). The cranks on my trek appear to move more freely than the BMC. When spinning backwards the BMC cranks stops sooner. The BMC also creates a clicking sound between the pedals (bottom bracket)
[MENTION=256459]rmf[/MENTION]lna the wheels are spinning freely. Honestly there is nothing slowing the wheels down.
[MENTION=35181]Reynolds[/MENTION] that's literally offensive and not helpful at all
[MENTION=81612]NFM[/MENTION]iso Good analysis and the BMC clearly has less rolling resistance. I can feel this when going down hills. The point missed is the Trek is converting more power from my legs to forward motion than the BMC. As soon as I need to pedal (to accelerate or maintain speed on an incline) the Trek outperforms my BMC. Let me say it another way. I can climb a hill easier in any gear on my heavier Trek with rubbing breaks than I can with the lightweight BMC. However if I go to the top of a hill and let both bikes just roll down and see how far they go when the road flattens the BMC will roll further with ease.
**The best way to describe it is as if someone has put gum between the cogs of a car gearbox. It wouldn't matter what gear you selected, the engine would need more power to get the car moving.**
On the BMC, it just takes more effort to turn the wheels from the pedals than it does on the Trek no matter the gear.