Considerations for a dedicated trainer bike

I have a basic hardtail (Trek Marlin) that I was thinking about using as a dedicated trainer bike on my Kickr Core. I ride road/gravel and don’t get along well with flat bars. I have an 11 speed 105 cassette on my Kickr since I’m using my road bike on it now.

My plan is to get cheap 11 speed brifters and derailleur, throw a 34T chainring on (biggest supported by the frame), and get an appropriate stem so I can closely match my fit to my road bike. It seems straightforward, but that usually means I’m missing something so I wanted to get some tips!

Fit: Is it worth getting a slightly more relaxed/upright fit? My road bike is relatively stretched out and I’m very comfortable on long rides outside, but I find myself wanting to sit a bit more upright inside.

Bars: I have basic aluminum bars I could throw on but I’ve seen some gross pics of what sweat can do over time. Should I perhaps do a wrap of electrical tape under the bar tape, or maybe get some super cheap carbon bars?

Bar tape: What would be reasonably durable/sweat proof? I’ve been running Supakaz and it’s fine outside with gloves, but can get a bit slippery inside.

Shifters: I’d like to stick with 11 speed Shimano (or compatible) so I can use my current cassette, chain and chainring. I can get used 105 shifters and derailleur around $250 or so. Are there other options I should look at (e.g. Microshift?). The bike currently has an XT shifter and SLX 11 speed derailleur. I thought about maybe getting bullhorn bars but can’t figure out how I could use my existing shifter since the bar diameters will be different. I’m not worried about brake compatibility because this bike will be permanently on the trainer.


Will you be riding / racing Zwift? Virtual shifting (e.g. Zwift Cog) gives you lots more options if your indoor bike has limited (or even non functional) gears.

For setup, my tip is to have fun experimenting with the super cheap stuff from AliExpress. Different width carbon bars, saddles, different size stems etc. Who cares if it’s not totally trustworthy at speed. :slight_smile:

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I have an old frame I put on the trainer. I just do TR workouts in ERG mode, so I didn’t put a front derailleur on and don’t have any cables run. I put an old, broken rear derailleur on to take up the chain slack, and cranked the limits way down so the chain rides on the 3rd smallest cog. I did put an old pair of shifters on to work as handrests. It’s worked great, but 100% dependent on ERG mode.


Should have added that I’m using an older Kickr Core. I’d like to be able to shift for VO2 intervals and maybe free riding in Zwift down the road, but I’m typically in erg mode 99% of the time :face_with_peeking_eye:

I just bought a $100 Lemond road bike to keep on my trainer. It’s awesome. It’s the same size as my other bikes, but with slightly higher handlebars for comfort. I also have the front tire raised 1”

I put on used aluminum bars with no bar tape. I wear gloves

The bike is 9 speed. I put the stock cassette on the trainer.


I think the most important consideration is whether the bike fits. I would try to mimic your road bike’s geometry as best as you can — if that is possible.

Otherwise, I’d probably sell the hardtail and get a road bike. Basically, considerations like weight won’t matter one bit. I’d put a used 11-speed rear derailleur on it and run it without a front derailleur.

Sweat is an issue, and you might want to think about getting cheaper carbon handlebars for that reason. My sweat corroded a Shimano shifter and a SRAM shifter.


As long as you can get the fit right, then it doesn’t matter whether it’s an MTB frame. If you can’t get it right, you could probably unload the Marlin for a couple hundred $ and find an old road bike that already is setup with road bars/groupset/etc.

I’ve got Sensah 11 speed on my trainer bike, super cheap and works. I’ve got no brakes or wheels, Kickr Core and a DIY fork stand.

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I should be able to get the fit where I need it on the Marlin.

I’ve been looking on Craigslist and Pinkbike and can’t find anything under $500 that isn’t a clapped out piece of junk :melting_face:

Do you know if Sensah stuff will work with Shimano chain rings/chain/cassette?

Yeah, 11-speed stuff is pretty much all compatible with each other, in regards to chainring/chain/cassette tooth width and such. Sensah SRX Pro is the 1x11 groupset meant for MTB cassettes (I think compatible up to 50t, but not for sure), Empire Pro is the 2x11 for road cassettes.

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Yes, unless you have a crazy fan setup .i.e an actual a wind tunnel. I;ve found I need to raise the bars a couple of inches over what I’d ride outside, when I have the wind supporting my upper body.

Aluminium bars are fine just don’t use bar tap and drape a clean towel over your bars so you’ve got something soft to grip. A wrap of electrical tape only makes the corrosion problem more hidden and worse.

see above, no need for bar tape, use a towel. Or if you’re flush with cash replace it several times a year.

the lowest cost option is to put the XT shifter on the tops of the drop bars, How often do you change gear indoors?. theres only 1/16" difference in diameter, but seeing as you’ll probably want to fit a set of Brfiters so you can ride on the hoods, I’d be looking for 2nd hand 105 on eBay or your local second hand marketplace. I picked up a used 10spd 105 group for £84, sold the cranks and FD separately, the brifters and RD ended up only costing £44!


Quick update… In an effort to get this up and running as cheaply as possible, I put $20 Amazon bullhorn bars on the Marlin and kept the SLX shifter right next to the stem. This gives me similar hand positions to being on the tops/hoods. Reach is just a bit shorter, but figured being a little more upright would be fine. Saddle is in the same position relative to the BB as my road bike.

I threw my Assiomas on the trainer bike and did a quick 20 min ride with different efforts (also to compare to the Kickr). It’s possible I’m tired still from last week and yesterday was a rest day, but RPE was through the roof for the same power. Assiomas tracked well to the Kickr so I think the power is reliable.

The Marlin has a 32T chainring and I was in a few gears in the middle of an 11-34 cassette, vs my road bike with a 50T big ring on the same cassette. I did 5 mins of sweetspot in that 20 min ride and wanted to quit cycling on the Marlin :rofl:

Can lower flywheel speed and a slighly different fit make sweetspot feel like threshold+ ? I’m going to try an easy endurance ride today, but had planned a few VO2 workouts this week so I’m trying to figure out if I should just stick to using my road bike.

Thanks for reading and any advice is appreciated!!

  • Yes, I firmly believe gearing and related flywheel speed are an important variable related to trainer use.

Here is a basic comparison I made related to higher and lower gearing. Just a quick ratio calc at the rear axle but it translates to flywheel speed:

Making large swings in gearing like you have done is likely to affect RPE even at the same power level measured with the same power meter. It’s one reason I recommend that people test and train using similar gearing when possible, and that is regardless of the trainer mode in use.


Thank you Chad! I saw some info about the higher flywheel “feeling” easier but I didn’t realize it would be so dramatic at the same power (but different bikes). I figured using the same calibrated Assiomas and Kickr, when they both read within a few watts, at least gave me some confidence the power part of the equation was right if the RPE was out of whack.

Say I put a 34T chainring on the Marlin and the fits are reasonably close…do you think the RPE “should” be similar to my road bike in the small (34T) chainring? I think the next step is to try that.

I was excited about the prospect of a dedicated trainer bike but this has been pretty eye opening!

Yeah at least with respect to flywheel, if you match gearing between bikes that factor is controlled. Bump from 32t to 34t will barely be noticeable and you can replicate it by choosing one cog smaller at the rear (if you’re not already on the 11t).

If you had a habit of using the 50t on your previous bike and anything in the middle of the rear, you may struggle to get that same “feel” and RPE unless you get much closer to that prior drive ratio.

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Thanks Chad!! :sunglasses:

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