Rear Pain During Long Indoor Rides

I’ve started doing some 2 hours rides on the trainer and have noticed my rear to starts to hurt around the 1:45 mark. I’m not experiencing numbness, sharp pain just an ache that says get off the seat. It is not the pelvic bones that are hurting, more the rear muscles. I don’t feel any of this type of pain while rides outdoors, which leads me to believe that sitting in one or two different positions inside (not stopping, unclipping, etc while outside) is causing the pain. I purchased new Rapha cycling shorts this year, have never used chamois cream and my saddle is 2-3 years old. Anyone else have this issue? Any remedies or suggestions?

The first thing to do is move around a little bit every now and again, say every 10 mins or so. 5-10 secs standing, sit up a little and reposition, move a little bit forward and then back. Just take the pressure off and get the blood moving around.


Probably the biggest thing you can do to help is to get a bike fit. If you’ve already had one complete on that bike, but it’s been a few years, then it might be time to revisit that and get another bike fit completed. It’s recommended to get a bike fit every year.

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@SDooley, I just added a post in the Equipment section with my primary recommendation for the problem you described.

When you have a bike that is perfectly comfortable outside, and then leads to problems when ridden inside, I feel it is important to look at what is different. When you do, there are two key differences.

  1. Lack of wind resistance on the body riding inside. That is a difference that I find because you end up with slightly more weight on the hands and arms, because you don’t have the wind pushing your upper body back.

    • To compensate for that, I recommend that people raise the front axle about 1"-2" [25mm-50mm] higher than the rear axle. This shifts the weight slightly back onto the saddle and off the hands and arms. That said, I don’t think that is your issue here.
  2. A bike mounted into a typical trainer ends up being very fixed and rigid in position. This can lead to excessive loading on the sit bones on the saddle because there is no shift in the demand on the muscles and tissue around them.

    • So, the solution I recommend is adding motion to the trainer setup. The Kinetic Rock and Roll trainer was my inspiration. But I made a simple double plate with a hinge that allowed me to mount a rigid trainer and turn it into a rocking trainer. These are called "Rocker Plates.

There have been a few commercial units around and more are appearing each year. There are lots of DIY solutions that helped drive the progression of their use. I pushed really hard last fall to get them into greater visibility and use. I published my plans for free and recommended people use them or their own designs. We saw an explosion in designs and builds, nearly all with positive comments about gains in comfort.

I feel this is because the rocker plate adds the freedom for the bike to shift left and right, even small amounts, and that leads to more comfort. Most people think they pedal a bike perfectly vertical, and they are very wrong. Each pedal stroke and movement leads to subtle shifts. Couple that with the fact that we constantly lean to change location on the road and to turn.

All of that leads me to my statement that there is nothing natural about using a rigid bike setup inside. Some amount of motion is appropriate. The amount of movement and centering force is something in debate and largely a preference of the rider. We use various springs to replace the balance gained from the geometry of a bike rolling on the road. So, it’s not a perfect proxy, but close enough to make it more like being on the road, especially when compared to a fully rigid setup.

I’m happy to answer more questions in the linked thread above. Hope this helps or you find another solution either way :smiley:


Good advice, but standing on a rigid trainer is an odd feeling and is a different motion than we use outside. That is one of the reasons I wanted a rocker plate, to make standing more natural. It works well for me, but I found that the seated comfort was as much if not more of a reason to use a rocker plate.

I have my centering springs set really loose, to the point I have to actually “balance” the bike like on rollers. The result for seated and standing is that they are very close to the feel out on the road. As such, I find myself more likely to stand for breaks, just like I do regularly outside.

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Getting fit is rarely a bad idea, but going on the OP’s statement that he is fine outside, I don’t think a fit is likely to be the solution in this case. He is comfortable outside with none of the stated issue.


@mcneese.chad - I read the title of the thread and said to myself. Chad’s going to be in here espousing the benefits of rocker plates. #notwrong Oh…ha ha…I had to sign up for TR so I could shadow you on another platform. :rofl:

@SDooley - So I struggled with this and getting saddle sores ever since I started Zwifting a year ago. Never an issue outside but long indoor sessions resulted in lots of saddle sores and more recently soreness. HTFU wasn’t working, new bibs weren’t working and even the rocker plate suggestion didn’t fully resolve it for me (but it does help). What DID work for me was moving to a wider saddle. Ever since Specialized started promoting their ass-o-meter and different width saddles I’ve always riding a 143mm saddle. That’s like 15+ years. And 143mm is fine for me outside for hours and hours. I started trying all sorts of saddles as was my girlfriend and it wasn’t until I bought a gravel bike recently which came with a Specialized Avatar 155 that I tried wider than 143. When I test rode my Warbird I was shocked that the wide saddle felt so good. Because my girlfriend had tried the Specialize Power in 155, and ridden it for many months) we had one laying around so I tossed it on my trainer bike. Whala (sp?) no more saddle sores and no more saddle discomfort.

TL/DR - try a wider saddle even if you’re normally fine on what you’ve got.


Agreed that proper saddle selection (shape and width) matter. I use the Spesh sizer in my fits and have adopted a wider saddle for my own use as well. Proper support under the sit bones is a prerequisite for getting comfortable on the bike. It’s the reason it is literally step #1 once you get to the “on-bike” stage of the BG/Retul fitting process.

And to clarify, I do not claim that a rocker plate is a magic cure-all. They don’t work for everyone. But they do help for many people. As such, I feel it is a worthy avenue to explore, for many riders.

Oh I don’t know…I’ve seen your Zwift Rocker plate FB group posts. Sounds like magic to me. :stuck_out_tongue_winking_eye:

Ah just realized it only shows my nickname…Chad - Grasschopper=John Farr your friendly neighborhood forum stalker.

So you run wider than the ass-o-meter suggests both indoor and out? Like I said, I’ve run 143mm Spec saddles since like 2003. First the Avatar and then the Toupe and Romin. My trainer bike started with a 143mm Avatar on it but when I started getting saddle sores I started down the saddle rabbit hole and have tried the Power Arc in 143, a Fabric Scoop and then the Power in 155 after my experience noted above. I actually am now using a WTB saddle that was a take off from my father’s CX bike and it’s 148mm and seems to work pretty well.

Thanks for the suggestions. I’m going to try the less expensive options first. I’ll set-up a fit session, after my race in a couple of weeks. It has been 3 years since my last fit session. I haven’t changed anything since then. I’ll discuss my saddle issue and see what he recommends, maybe a wider saddle is necessary. I plan on keeping these 2 hour rides a staple going forward

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Was thinking about a wider saddle last week, thanks for chiming in.

Couple years ago I had the Retul fit and upgraded my saddle to a high-end Selle SMP Pro and proceeded to do a series of long 6+ hour century rides in the mountains. No real issues with my saddle before buying the Kickr 2017 a year ago.

Recently started doing longer intervals on the trainer, and my butt hurt last Wed after doing the 2.25 hour Warren ride. Rode 82 miles on Saturday, the first 3 hours in the drops and no problems outside. Heck, even the shorter trainer rides have led to some pain, and so at least in my mind the fixed position is the root cause. But I don’t know for sure.

I’m going to try building my own DIY rocker plate first, and if that doesn’t improve things will check out saddles next.

LOL, the nicknames aren’t my favorite in here. Gotta learn who everyone is again :stuck_out_tongue:

I am on the line of sizes, so I tend to recommend going larger when that’s the case. I tend to see more issues when people are on too narrow of a saddle, as opposed to too wide. On occasion, people will complain of low glute issues if it’s too wide, but excess pressure and odd seating on too narrow seems the bigger issue in my experience.

I’m gonna tell you how to fix this & it’s SOOO simple. A wiley old endurance biker taught me this trick.

Notice when you start to get those aches? 1:45. How long does it take to deplete liver/muscle glycogen? About 90 minutes.

One thing about muscular glycogen is that it is associated with a lot of water. If you deplete you loose water. You’re losing water from tissues that house the glycogen. So imagine your muscle like a gel pad…when it’s got all that glycogen & associated water in it everything is firm and supportive. As glycogen depletes and water comes out it turns into a flaccid bag that doesn’t support as well. And you start to get achey.

So, simple solution. For longer rides set a 20 minute timer and take down 22 grams of fast acting carbs on that timer. Hydrate accordingly. Your aches will be much improved.

Another trick that Allen Lim taught me: before a ride mix two tablespoons of dextrose and 1/3 tsp of salt in a liter of water. Drink it before you start the ride. (gotta luv a guy who will tell you ‘don’t buy my product. here’s how to do it yourself for much cheaper’) You’re sure to start off hydrated and it’s like having an extra 32oz water bottle on your bike. The downside is you’ll have to take a nature break but since you’re indoors anyhow…


1/3 TEASPOON salt per liter. Yikes!


Are you doing some off the bike core/strength work?

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All good advices above. I want to add my two cents:

  • my personal biggest improvements in fighting back pain (off the bike) was strength work. Since that I never had an issue like before.

  • training indoors is a very static thing. You don’t do any movements to hide your weaknesses like you do unconsciously outdoors (leaning your bike 2mm to the right for example). And if you do more low intensity than you do outdoors (like most of us do) your legs don’t carry as much weight as they do outdoors. Your doing more a steady bench press than a sitting running (hope you get it).

  • and all for most: it just hurts at some time. There are less impressions, it’s sometimes boring and and it’s less fun. If all other things are alright: get pain known as a new friend. :slight_smile:

Just finished the 2:30:00 Koip workout and my rear end is fine. The no-cost solution? Every 30-40 minutes I stopped, got off the bike for 30-90 seconds, and then jumped back on and kept going.

In an effort not to hijack this thread (not sorry) what the difference between the Retul saddle pressure instrument and the Spesh sizer? My fitter is in North Texas and uses Retul. From the little I know, I agree with dealing with the bump and the first contact point to address with fit issues. I too experience discomfort on the trainer but part of my issue was poor posture/form, worn out bib, or 2hour sessions. Rocker plates are definitely something I’m considering.

I’ll second @mcneese.chad comments on a rocker plate helping for this. It definitely has made the longer rides more comfortable. If you’re handy you can build a simple one for less than the cost of a new saddle or a fit. Even if it doesn’t ‘fix’ your issue, I think the benefits of a rocker plate would be additive to a better fit or saddle change.

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That works, but I think breaking the workout by stopping and getting off like that hurts the maximum potential of maintaining pedaling through the entire workout.

It’s entirely possible that I am odd, because I have a goal of not coasting in the long endurance workouts. It’s an effort to maximize the effectiveness of being on a trainer since you can pedal 100% of the workout.