Why is my new MTB slow? Please help me to make me faster again

Note: OEM tires are rarely the same as the replacement ones you might buy in the store. For example, the Specialized Ground Control T5 (?) tires that came on my Chisel were +100gr/tire over the similar version Spec had listed. I think they’re made to leak less air and last longer. Not sure if Maxxis does this, but

ALWAYS toss the OEM tires. That’s how they make the $12k bike feel faster than the $3k bike.


If you’re riding off-road, line choice matters a lot. You prob just rode better lines in the past. Also, Strava/gps is pretty sketchy with off-road segments. I wouldn’t read into it too much


Line choice is a valid point. Nevertheless these segments are on very smooth gravel. We call them in Germany „forest-autobahn“. They are absolutely non-technical and have nothing to do with single tracks. That‘s why I look at these especially.
I recorded the race with my Wahoo Bolt and my Apple Watch. Both show the same times in Strava. I have also 3 laps in these with same results. These segments are also the longer ones were I could put out smooth power without spikes.

You are riding non-technical gravel… suited for a hard tail. You lose force in the “squish” of the full suspension.

What was your total time and how did it compare? Did you make up time on the more tech sections? I am guessing if you rode more technical, challenging trails the FS would be superior to the hardtail.

Yes, for such XCM races I wouldn‘t need a full suspension bike. But I can lock the fork and the shock to prevent any squishing. There weren’t many sections to make up time in the downhills.

The overall time was the same, however I had a significant higher average and normalized power. But I don‘t wanna focus on the overall because there were sections which I can‘t compare from last year to this year.

I haven’t looked up the Scale geo, but it would surprise me that the Spark has a shorter reach. Did you buy a smaller size Spark?

You should be sitting further forward (relative the BB) and the bars should be lower and further away. I will go and compare the Geo’s now though as I’m curious.

I agree with others, it’s most likely tyres. Though the Maxxis tyres spec’d OEM are likely not too bad if they are 120TPI. Maxxis also do their tan wall in a pretty interesting way - it’s an extra layer of coloured rubber as far as I can tell, unlike other brands where it’s less rubber - those tyres could be unusually slow. Aspen’s are very fast.

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Thanks everyone so far for the really good discussion.

I think @ArHu74 @MI-XC @liam_mail @jfranci3 were spot on with the comments on OEM tires. I wasn‘t aware of that and the noticable worst performance.

I just did another test. I put the 2.35 Mezcal on my old aluminium rims. This configuration is ~1kg heavier (but I couldn‘t bring the Mezcal on my carbon rims - maybe I need a better technique?).

I rode the same segment which I used to test the tire pressures. Both configurations were with 19/20 psi.

I rode at 250 W and gained 6s. The segments in my races I rode with ~320-340 W. So this would give me a large part of the time back.
I did another run with 15/16psi which was 4s slower.


Both bikes are size L. If I remember correctly then I turned the stem around on my Scale from the stock configuration to have the bars lower.

Watch the video on installing cushcore. It’s quite informative in general. You should be able to get the Mezcals on there. More suds, and make sure the bead is sitting in the centre groove so you have as much slack as possible to pop the last section on.

Far be it from me to tell you how to set your bike up, and it’s obviously very important to maximise your comfort, but I’d see if I could progressively move your position to utilise the modern geometry. It’ll give you more balanced traction and I think a better pedaling position. Plus, it’ll be more aero.

@liam_mail thanks. Awesome advices. I will check out the video.