My road bike is in the shop and I have temporarily mounted my mountain bike to the trainer. My LBS loaned me a 11–32 road cassette, which isn’t ideal in terms of gearing, but works.
This morning, I tried to do a sweet spot workout and it just wasn’t happening, and I wanted to tap into the hive mind that is the TR forum to figure out what improvements I can do. Here are some issues:
I felt a lot more strain on my muscles and I was much more out of breath.
My MTB has a Rotor 2InPower power meter, which I use with power match. My road bike has a Quarq power meter. Even if the readings are somewhat different (I can’t compare them directly), I was struggling to put out wattage I can easily hold outdoors.
I use resistance mode for my workouts. I tried to lower the resistance so that I am in a gear that produces a higher flywheel speed for more felt inertia. It was better, but still not great.
Cooling was an issue. The wider wheels and fork seemed to block more air from my fan.
Any ideas on what I can do to troubleshoot and/or improve my setup? It is just temporary and I am just in the pre-season as far as training is concerned, i. e. I haven’t started a training plan, but I am training regularly, getting into the groove so-to-speak.
It’s likely that the position of the saddle in relation to the BB is quote different on your MTB, which is why you are feeling muscle strain. Depending on your MTBs seat tube angle and seatpost setback, I’d be adjusting it to get as close as possible to my road bike position. Next thing to sort is the bar position which affects hip angle how open your chest is etc.
I’ll give you my take as someone who does the bulk of his Spring and Summer training on his MTB - including a lot of Road Miles and a lot of time on the trainer (Leadville Prep)
Biggest factor for me would be different power meter putting out different numbers. For me - The position difference between my MTB, Gravel Bike, Road Bike is a bit different, but it’s usually going the other way getting used to my Road Bike with the Stretched out position. Putting out Power just isn’t that different once I make sure Power Meters are close. To make sure of this - I do a lot of dual recording on the trainer and calibrate my Quarqs to match (using the trainer or a set of Assioma pedals as reference)
With that said - I would try and tweak the position to be as similar as possible. Longer Lower stem, narrower bars could help, swap bar spacers to above the stem for a quick fix… Biggest issue though is probably Saddle / BB as mentioned above.
Drivetrain loss would not be it unless you’re using the trainer as the Power Meter - otherwise Quarq, Pedals, all power meters at the crank come before the loss.
But - if it’s short term, just ride by RPE / Heart Rate. No harm in adjusting your zones up or down a bit if you’re getting the same impact.
once you get your road bike back, I would check to see if both power meters are reading the same. You can do this by not power matching and dual recording the trainer and PM separately, then switch bikes and do it again. use the trainer to be the common power source to compare the two. kimda pointless to have to PMs reading different.
I suspect not. The 2InPower hasn’t tested particularly well, but I couldn’t resist one of Rotor’s fire sales (they are in financial trouble) as I needed a new crank anyway. On a commuter, I don’t care as much if it reads low compared to the Quarq.
It doesn’t help that as far as I understand I can only zero it via Rotor’s app (it is a two-stage process and connecting the power meter via Bluetooth to Rotor’s own app is finicky).
I also bought a new Rotor Inpower before Breck Epic since it was so cheap. I already had the same power meter, but in 175mm crank length and I thought might as well get the same power meter in 165mm since they were so cheap.
I tell ya, I was having so many issues getting this thing to pair with the Rotor App to zero it and then calibeatre - and have somewhat accurate readings compared to my older InPower. Eventually, the morning of Breck Epic, I got the damn thing to pair properly with my Garmin despite conflicting documentation on which pedal is at 12 or 6 when calibrating. I had to use the battery cap from the old power meter to get the battery to seat properly. Hoping now I can go back to the new battery camp thing.
I think it reads a bit lower than my Garmin Rally pedals, but since that hiccup, has been consistent.
Good to know that “I’m not holding it wrong.” The calibration process is so much more finicky that I am not zeroing my power meter very often. With my Quarq I do that every time before a ride even though I probably don’t have to.
Honestly, the price was so low that if push comes to shove and I would use my mountain bike or its successor for more serious stuff, I would consider getting a pair of Faveros.
My reasons were cheap + I really wanted 165 mm cranks on all of my bikes + my 175 mm XTR cranks had a crank in them. (Although I only discovered the crack when I installed the Rotor cranks.)
Is your MTB a full suspension and if so, was it locked out rigid? Suspension bob will cause your PM to underreport by a slight bit. Also potential for differences in calibration between the two PM’s. Then what everyone else said, fit/position is likely different.
I’d also echo what some others are saying here about positioning.
A lot of MTBs (even XC bikes now) are really designed for seated pedaling uphill, which means that the STA is quite steep. If you’re used to doing workouts on a road bike, you’ll probably notice more fatigue in your quads.
For those who don’t do so much steep climbing with their XC bikes, it seems that moving the saddle back can help a lot for longer days in the saddle with some flat pedaling.
I have two trainers side by side. My gravel bike on a wahoo kickr v6 mounted to an inside ride e flex plus, next to my Epic 8 on a wahoo kickr v6 with some Etsy racquetball attachments which helps a ton.
On both trainers, I have a Zwift cog installed so any bike can be used, although I have a sram xx with 10-52 on both bikes. I control the wahoo resistance through my garmin head unit and run the power from my crank based power to my iPad which runs TR.
Until early summer, I hardly ever used the MTB on the trainer as I’d been using the gravel bike on the trainer for a year and a half. Once I finished my last gravel race and started preparing for the high Cascade 100 (mtb race), I spent 100% of my time on the mtb. I went from being “meh” to absolutely loving it. It may even be better than my gravel bike. Granted, going back to some rides on the gravel bike on the trainer likely was just lack of riding it for a couple months.
My mtb is set up with same length cranks (165) and a 90mm stem that puts me in a very comfortable position for flats and climbing. It’s not as preferred for descents, but too comfortable otherwise. The inner bar ends are great when I want an aero position or changing hand locations.
I’d check dimensions, setback, saddle levelness, etc., to see where you’re at.
Come winter in the PNW, I’m not sure which bike on the trainer I’ll be spending more time on. Have one more mtb race in 3 weeks and then the start of offseason. Easy to switch between bikes on a whim.
Yes, currently only one fan. On my road bike one fan works well enough, but perhaps I’ll upgrade eventually to two.
Yup, exactly, my quads felt unusually tired.
So it seems it might be a case of “all of the above”. I’ll check the power meter situation by tracking the power numbers of my trainer. I haven’t compared the power numbers of my Suito to the Quarq lately, but they were vastly different, too, both, in terms of slope and offset. Seems like I might have a case of three power meters all disagreeing!
