Hacking a slightly too-large frame for my purposes… help?

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byogman
Member
#

Not too far back I picked up an old school 54cm road bike, with the intention of giving it away to someone a bit taller who would’ve had good use for it… but he’s too far out of the city now.

In the meantime I noticed something rather interesting, which is that with the larger frame, my laptop could just nest in the front triangle with the long edge on the downtube (albeit with very little room to spare).

So this is a question in two parts. First of all, how to hack a frame bag together and especially do the padding as robustly as possible given the limited room? Bonus if it’s a mod on the bike (ok if it’s permanent) and the frame bag itself can be as normal as possible, but really, anything that works is a big score.

Second of all, how hackable is the reach in a situation where the top tube is honestly a little too long? Anything allow you to bring saddle a bit more forward than just sliding it as far forward as possible on the rails?

Obviously there’s the stem which could be shorter (though it’s not especially long). Does a shorter stem front to back make steering twitchy? Is the same thing equally true of anything that brings the hands back, all other things being equal?

The same basic questions about front to back sizing adjustability also applied in terms of a recent almost N+1 on a folder a ways back and could easily apply in the future. I didn’t have quite enough use for such a thing just for myself but it would have made more sense if it were something my eldest daughter could have ridden over a range of years.


Jacob McCrea
Participant
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Regarding your second question, while it is physically possible to cut a frame apart and shorten the length/wheelbase so that it fits a shorter rider, I think it would be an extreme waste of time unless you (1) already owned the necessary litany of expensive fabrication equipment; (2) were a fairly proficient welder and fabricator; and (3) had a really good reason (and I can’t think of any). Dollar for dollar, and hour for hour, I believe the best you can do is install a shorter stem and bars with a shorter reach. I don’t mean to be too negative about this, just honest and direct.

As for how a slightly shorter stem will affect handing, my experience is that the difference is negligible.


reddan
Keymaster
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@byogman: perhaps replacing the bars with a more swept-back set (a la Nitto Promenades) would help? I may have a spare set that you could use.

You’d likely have to swap brake levers for MTB-style ones, unless you can somehow convince the existing road levers to play nicely with the new bars.


ericf
Participant
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I would try a shorter stem and swept back bars. Throw ’em on and ride the bike. If it feels good you win, if not, at least you tried. Best way to learn.


jonawebb
Participant
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You can also reverse the seat post to move the seat a bit more forward.


Jacob McCrea
Participant
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Ben, if you have not done so already, it would be well worth your time to read Andy Pruitt’s Complete Medical Guide for Cyclists, particularly the chapters on bike fit. I found the chapters on bike fit to be very helpful and I think they would give you a clear understanding of what is, and is not, a proper fit.

By the way, I recall you had some back troubles with a single speed bike that was probably a little too large for you, and you received a lot of sound advice on this board. Is that the same bike you mention in this thread? More importantly, did you follow any of that advice, and if so, what was the result?


byogman
Member
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Problem with the back went away by itself by just laying off a bit, mainly on the determination to crank up my super-steep driveway (now that’s fine too, but I had to give myself a little time without that stress and work my way back into it).

Anyways, this dicussion is on a different bike, the change has more to do with the fact that my towing duties now involve some more gradients and climbing. Nothing all that serious mind you, but eh… what exactly am I trying to prove? Plus the road bike is fun.

Will be reversing the seat post shortly, thanks for that pointer. With the seat forward on the rails and soon, more so still with the reversed seatpost, and the (likely) still bit of a stretch position was also thinking that in some ways my position was a little more tri-bike like than road bike.

So, maybe if I could hacksaw some short lengths of conduit, plug them into the then end of the bars that hook back, and pad them with pool noodle or some such nonesense, I could get a little more support for that slightly extended very aggressively bent over position?


Jacob McCrea
Participant
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Glad to hear that your back is better. I have a number of concerns about what you suggest in your last paragraph. The short of it is that you could create a very unsafe situation. I would write it all out here but the hour is getting late. Feel free to call any time and I will explain it. You should have my phone number, and if not, let me know and I’ll send it to you.


byogman
Member
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I run thought experiments with a lot of things with few filters, so it’s not surprising to me to hear stuff like this.

Still, would like a little more in the way of specifics before I decide. Very tempted by the seat post reversal in particular since it’s so easy to try. Assuming I can adjust the angle of the saddle to something surface level reasonable, that is.

Otherwise, yeah, it definitely would put my weight further forward, be careful with decents and feel things out carefully in terms of turning dynamics before getting aggressive. Which would be true with a tri-bike for the same reasons… no? More to it than that?

Anyways, missed you over lunch. If you see a missed call from a 919 area code, you can call it whenever’s convenient.

Or post here, seems like good content for the thread.


reddan
Keymaster
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@byogman: if nothing else, be aware of your knees if you choose to move the saddle that far forward…I suspect you’ll be pedaling “back” a bit instead of just “down”, with the seat moving forward in relation to the bottom bracket. While I’m no fit expert or ergonomic guru, that seems likely to be tough on the knees.

Extending the bars would certainly affect the steering…you’d need to move those bar extensions further left or right to produce the same amount of rotation at the steerer. I don’t know how that would affect your particular bike…might make handling better, might make it worse.

From a mechanical perspective, I’d be very concerned about extending the bar ends with anything non-structural; having one of them pop off while you’re hauling on the bars would be safety-disadvantageous. I wouldn’t be comfortable with anything short of a well-soldered joint with lots of overlap between the bars and the extensions. (Also, If the bars are aluminum, you can’t really solder them, so you’d need to rely on an epoxy or other glue of some kind…not something I’d want to trust.)


Swalfoort
Participant
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Plan B……smaller bike, one that fits safely and comfortably. And a smaller laptop! Probably cheaper and safer in the long run, unless you have a really big/fast laptop, and need all that capacity.


byogman
Member
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Work laptop, and I need a machine with some horsepower and a good sized screen in any case.

I will at some point probably get out of this mode trying to make basically silly things work well enough and select the right tool for the job, even if it means I have to pay for it. Just not yet.

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