Opinions: Rather go a frame size up or down?

I am considering pulling the trigger on the Canyon Speedmax CF 8.0 SL. With a height of 177 cm and an inseam of 83 cm their sizing tool places me on an medium sized frame. If my inseam would be 82 it would be a small sized frame.

As I wont have access to a fitter in the foreseeable future, I figured I better reach out to you guys and ask for your opinion. So, what would you do?

Thanks in advance for your feedback. It’s highly appreciated.

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Go down. Could also throw on a longer stem and setback seat post.



Can I answer a question with a question? :wink:

Do you currently have a bike, and the X/Y location of your cockpit related to the pads, aero bars, and saddle?

  • Sizing to this is often a better direction to work from when looking at a TT/Tri bike (as compared to typical height/inseam).
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I do have a road bike with clip on bars. Though the fit is very poor. I just used it to get more acquainted to the different angles. Certainly no good for a baseline.

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Even with that, you may have worthwhile info to add to the discussion. I’d suggest capturing that info, with a mind towards any feel you may have, and couple it with the other sizing info.

I am no TT/Tri expert, but might be able to expand on recommendations with some pics of you on the bike, along with your current feelings about it.

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I’d always go with a smaller frame. you have a much wider range of options to adjust your position.

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Maybe. But I want to point out the specifics of the OP’s question here, that is related to a TT/Tri bike. This alters the view a bit, IMHO, because the ability to make wide ranges of adjustments may well be less than a typical road bike. At the very least, it is often more complicated requiring special parts and/or limits.

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fair point. I can’t say I have much experience with TT set-ups

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Right now I am super unsure wether the information wouldn’t skew your judgement. The saddle is too far back, the bars are too high, and the pads too far back. It’s pretty much a mess.
It is mostly caused by the limitations of my bike in terms of saddle position and steerer tube/spacers. If I could, I would have move the saddle forward, the bars lower and the pads also more forward. Though unfortunately, this is not an option.

Hope this makes sense. Nevertheless, I will look into it and give it a second thought!

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I totally get it. Road bikes make bad TT/Tri bikes, who wudda thunk it :stuck_out_tongue:

If you haven’t already looked, Slow Twitch may be the better place for a question like this since they have WAY more experience than I ever will. I suspect there are some existing TR forum members with the same bike, and may be able to offer some insight too. But ST is the place that should have a greater depth of info to offer.

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I have a speedmax, and based on my personal experience I’d say size down. I was in between a XS and a S, and the XS was perfect for me. That being said I’m no bike fitter, so I’d recommend maybe contacting them. There’s also a ‘fit assistance’ thread for Canyons on slowtwitch, which looks to be pretty detailed :grin:


I am about to start building a bike, that is based on a frame that is one size down from what I usually ride (46.5 vs. 50).

One of the downsides of going shorter wheel base, is that the bike becomes less stable. That, combined with a long stem, say 120mm up from the usual 90mm can make the handling a bit unpredictable, as you have slower initial steering, followed by a snap.

Pros and cons to both. Ideally of course, you want the frame that fits your body type, rather than having to compensate by going for longer or shorter stems or cranks.

PS. By the way, please do not look at the professional athletes as an indication of what YOUR OWN set up should look like. There are a LOT of cases where some (just like many of us) do it for the looks only.


I’m definitely not an expert… just someone who has spent a lot of time figuring out what TT size works for me. Understanding there’s a lot of unknowns here… Most bikes have some adjustability up/down and if you’re right between sizes it probably doesn’t matter as there will be decent overlap in possible setups. Think about things that would push you to one side or the other (flexibility, leg/torso length, etc). For example if you have a long torso then get the med and if a shorter torso get the small. It’s easier IMO to get the stack right, assuming you don’t need to go below the med slammed (if you think that’s a possibility in the future def get the small). Also, if you have poor flexibility maybe size up.

If you really are in between and both would support your pos, some would argue to get the larger frame as the taller frame is more aero than the things you have to do to add stack… but I don’t think it matters and would pick whatever you think looks better.

FWIW, I went with a TT bike that is considerably smaller than my road. I’m 188cm and ride a 58cm tarmac with 81cm saddle height, 120 stem, yada yada.

My TT bike is a medium argon 18 E-116 and it fits great and has some room for me to drop the front end over time. Easy these days to add some stack to a smaller frame if you need it, harder to shorten the reach if the frame is too long or drop the stack if it’s too tall… I am all legs so went with a shorter frame. I could easily get the large into same position, but the XL would be too big (long).

At the end of the day even an estimate of your initial pad X/Y as well as long term desire (i.e. maybe drop stack over time as you get used to pos) would go a long way towards making the decision.