# Significant Saddle Height Discrepancy On Trainer



## fatbaxcat (Nov 30, 2008)

Hello. Curious if anyone else has experienced this situation. When I put my bike on the trainer after riding outside, I need to lower the saddle by about 5/8"! I feel like I cannot get any power or fluidity through the stroke while on the trainer until I lower the saddle by this much. Conversely, when I go back outside, I feel like I am kneeing myself in the chin, and my hips and inside thigh muscles get toasted very quickly. When I raise it back up, it feels fluid and I still feel stable on the saddle. 

I can't make any sense of it. Only considerations I have are possibly that the bike is moving significantly underneath me while on the road. Or, perhaps, muscle recruitment is slightly different while fighting forward movement and wind resistance, which may alter how you power through the bike. 

Interested for any detective work.


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## tlg (May 11, 2011)

It's impossible for your saddle height to change merely by putting your bike on a trainer.
Do you have a block under your front wheel? Most trainers raise the height of the bike. If you don't raise your front wheel to match, your bike will be tilted forward an inch or so. This isn't a saddle height discrepancy. But it could give you the sensation of such from leaning forward.


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## fatbaxcat (Nov 30, 2008)

tlg said:


> It's impossible for your saddle height to change merely by putting your bike on a trainer.
> Do you have a block under your front wheel? Most trainers raise the height of the bike. If you don't raise your front wheel to match, your bike will be tilted forward an inch or so. This isn't a saddle height discrepancy. But it could give you the sensation of such from leaning forward.


Thanks for the reply--no, it's even more simple. The bike feels just all wrong while pedaling on the trainer, until I lower the saddle. I use a level at the axle points to make sure the bike is plumb.


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## duriel (Oct 10, 2013)

That must be a long level!


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## Peter P. (Dec 30, 2006)

Is it possible? Yes.

While on a trainer, your pedal stroke is not the same as riding on the road because of gravity and road tilt. Resistance on the trainer is too "even". As a result, your downstroke is not as powerful and if you could put a weight scale under your saddle, you'd find that on the road you're actually lifting yourself off the saddle on the downstroke, or at least your pressure on the saddle is reduced.

I believe that is what you're experiencing.


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## tlg (May 11, 2011)

duriel said:


> That must be a long level!


What? Road bike wheelbase is ~39-40".
You don't have a 48" level? Pffft. I got two. And a 6ft. 
Plus you could use a string and a short level.
C'mon man up.


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## duriel (Oct 10, 2013)

Women like men with long levels? Who knew!


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## fatbaxcat (Nov 30, 2008)

duriel said:


> That must be a long level!


Carpenter level


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## fatbaxcat (Nov 30, 2008)

Peter P. said:


> Is it possible? Yes.
> 
> While on a trainer, your pedal stroke is not the same as riding on the road because of gravity and road tilt. Resistance on the trainer is too "even". As a result, your downstroke is not as powerful and if you could put a weight scale under your saddle, you'd find that on the road you're actually lifting yourself off the saddle on the downstroke, or at least your pressure on the saddle is reduced.
> 
> I believe that is what you're experiencing.


That makes perfect sense. I just seems as though I am not getting any strong downward force. My heartrate also evens out on the trainer when I lower my saddle, so that seems consistent with what you are saying. I ride on the trainer alot, so I maybe be a lot more sensitive to this effect than most. Thanks for the great feedback!


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## tlg (May 11, 2011)

fatbaxcat said:


> That makes perfect sense. I just seems as though I am not getting any strong downward force. My heartrate also evens out on the trainer when I lower my saddle, so that seems consistent with what you are saying. I ride on the trainer alot, so I maybe be a lot more sensitive to this effect than most. Thanks for the great feedback!


What kind of trainer do you have?


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## fatbaxcat (Nov 30, 2008)

tlg said:


> What kind of trainer do you have?


I have an older 1upUSA trainer. Huge flywheel, I really like it. Not a smart trainer though.


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## duriel (Oct 10, 2013)

Well on that trainer, you can't lean left-right. You would be surprized maybe by how you throw your bike left-right while really riding on the road, particularly when you stand.


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## smokersteve (May 22, 2016)

It makes zero sense to have to change saddle height from riding outside to riding on any type of trainer. Zero sense. I’ve used dumb trainers, smart trainers, various types of rollers…all at the same saddle height.
Your peddle stroke cannot and won’t change just because your bike is on asphalt or rollers or attached to a trainer. Correct knee angle is correct knee angle. 
Also 5/8 inch height change is a lot for moving a saddle. I can notice when I lower or raise my saddle 2 mm.


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## tlg (May 11, 2011)

fatbaxcat said:


> I have an older 1upUSA trainer. Huge flywheel, I really like it. Not a smart trainer though.


 I used to get knee pain riding a standard trainer. Similar symptoms you describe. I could barely tolerate an hour on it.
After I got a Tacx Neo, it was a world of difference. The electronic flywheel provides varying resistance. And it has a few degrees of rocking side to side. I can ride for 3hrs and no knee pain.


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## fatbaxcat (Nov 30, 2008)

smokersteve said:


> It makes zero sense to have to change saddle height from riding outside to riding on any type of trainer. Zero sense. I’ve used dumb trainers, smart trainers, various types of rollers…all at the same saddle height.
> Your peddle stroke cannot and won’t change just because your bike is on asphalt or rollers or attached to a trainer. Correct knee angle is correct knee angle.
> Also 5/8 inch height change is a lot for moving a saddle. I can notice when I lower or raise my saddle 2 mm.


That's why I asked for input.


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## PBL450 (Apr 12, 2014)

smokersteve said:


> It makes zero sense to have to change saddle height from riding outside to riding on any type of trainer. Zero sense. I’ve used dumb trainers, smart trainers, various types of rollers…all at the same saddle height.
> Your peddle stroke cannot and won’t change just because your bike is on asphalt or rollers or attached to a trainer. Correct knee angle is correct knee angle.
> Also 5/8 inch height change is a lot for moving a saddle. I can notice when I lower or raise my saddle 2 mm.


Exactly this. Kurt Kinetic and rollers. No saddle adjustment. Any change n saddle height will be communicated by my right knee rather quickly. 5/8ths of an inch is massive.


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## Coolhand (Jul 28, 2002)

See if you can borrow a different trainer- the road fit should be the correct one. Unless _neither_ is quite right (road a bit too high, trainer too low to compensate)


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## Oldteen (Sep 7, 2005)

A bit late to the thread (been away for a while), but over the decades I've never felt the need to change saddle height going from road to trainer (always use a front wheel block). While I understand Peter P's point about road vs trainer pedaling sensation difference I've never thought about changing seat height because of it. 
In any case, agree that sudden 5/8" change in seat height is quite large (assuming initial fit is reasonable).


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