I recently bought an 13.5 Trek Cali for my daughter (9 years old). I got an incredible deal on it and bought it sight unseen from an out of town seller. After getting it, I realized it had 29" wheels on it instead of the 27.5 the more current models have. I was actually looking for a 26" at the time, but it was such a great deal, I couldn't pass it up.

I like that it is something she will be able to grow into, but the tires are absolutely huge for her. I did some modifications (moved some spacers and flipped the stem) so it is definitely ridable.

I am curious if I could throw some older 26" wheels on the bike for the next year or two until she gets more comfortable with the bigger wheels. It has disc brakes so that shouldn't be an issue.

I know she is going to have a much lower BB that may lead to a few pedal strikes and it is going to look a bit akward with the longer seat tubes and forks. But since I am changing both wheels, it shouldn't affect the overall geometry too much.

So what do you think? I know it isn't ideal, but any reason it wouldn't work?


I have seen this question, but it addresses only changing the front wheel (which would change geometry. And also this question about going down to 27.5, but he is looking more for performance improvements.

  • Are you sure it's a 29" wheel bike? I googled the Trek Cali and only found 27.5" wheel bikes in the 13,5" small size. Jul 2, 2018 at 18:01
  • 100% sure. Frame says Virtual 14", Actual 13". It is running 29x2 Bontager with a 29" fork up front. I was like you, I did my google searches and figured it was a 27.5. While not ideal, I thought my daughter could handle it. I am guessing it is 3 or so years old. Perhaps before Trek started adjusting their smaller frames to run smaller wheels.
    – kickert
    Jul 2, 2018 at 18:08
  • Is the bike truly ridable? Is the stand-over low enough? If so, wheels just looking too big are not really a problem. Jul 2, 2018 at 18:29
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    I have trouble believing a 9-year-old can ride a 29" bike. How tall is she? Jul 2, 2018 at 19:21
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    Yes- good kids bikes are hens teeth and expensive for the 1-2 years you get out of them. 26" inch wheels makes a lot of sense. The bike IS too big for your daughter, anything you can do to make it a better fit will be a big benefit. Also consider shorter cranks as well. It will make the bike fit a 9yo infinitely better.
    – mattnz
    Jul 2, 2018 at 20:19

1 Answer 1


If you look at bike literature from the early 29er years it was the best thing to buy. There were some issues that showed up after they became common enough for recreational riders. Recommended frame sizes tended to put people on a frame that was actually to large. It seemed that they forgot about the top tube being raised 1 1/2 inches by the larger wheels. Another issue when 29 inch wheels were put on small frame sizes was toes striking the wheels while turning and pedaling. So while a small size 29er may seem odd now they were a one point common. Manufacturers seem to have learned a lesson from all this and now put 26 inch wheels on the smallest frames 27.5 on the less small frames and make larger frames in both 27.5 and 29. All this is just to explain why you have a small frame with 29 inch wheels. The good news is that with the 27.5 boom 26 inch disc wheels are available with steep discounts. I don't see any reason it wouldn't work. It might be cheaper to buy an entire used bike if you add in tires and tubes. Use the wheels until she out grows them, put the 26's back on the used bike and sell the whole bike for likely close to what you paid for it.

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    I appreciate the input. I couldn't think of a reason it would cause adverse effects, but wanted to check. Having disc brakes certainly simplifies things. I'll keep an eye out for an older 26" bike with disc brakes, but for now I am hoping I can someone who has upgraded a bike and has an old set laying around.
    – kickert
    Jul 2, 2018 at 20:09
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    Pedal strikes would be the main drawback
    – Rider_X
    Jul 3, 2018 at 1:43
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    Provided your daughter doesn't ride over extremely technical terrain with lots of pedal placement and stroke juggling, the pedal strikes won't be a big issue. On the other hand, the lower clearance will be a shortcoming if she likes/learns to ride technical terrain.
    – Gabriel
    Jul 3, 2018 at 19:20

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