Bike too large, if I change the wheels to a smaller size will this lower the height?

Question

I've got a second hand Raleigh racing bicycle. The frame is too big, when I stand on the bike, off the seat, my toes only just touch the ground. I'm not thinking this is safe to ride around London. I want to use it, buying another bike is not an option at the moment.

If I change the wheel size, rims, to a smaller size will this lower the height of the bike?

I measured the rims diameter 25 inches. If I got smaller wheels would this work? I've lowered the seat as far as it can, and the handle bars too.

I have another bike (Green Raleigh), which is broken, and the rims measure 22.5 inches. I could ride that bike without any trouble, although the frame was smaller.

Any advice would be great, really need some help about this, I can post up pictures of the bike too if this helps.

Thanks

edit:

The brakes, same back and front wheel.

Gears

When I stand either side of the top bar my toes are flat, with my heels raised high, and can balance myself but hard to mount and dismount the seat generally. If I had even half an inch off the bikes height this would make a difference. I'm 5'7, M, 22, I may grow a bit more, though not holding my breath.

Wheels (700x35C/37 - 622 (26x13/6 x 15/8)

Rim 27 x 1 1/4

When cycling I was straining slightly to reach the pedals, my legs were fully streched out, but still in contact with the pedals.

Would smaller tyres fit and lower the bike half an inch, or is this to do with the frame size?

Hope this helps, thanks!

Answer 1

There are several issues worth addressing.

The frame is too big, when I stand on the bike, off the seat, my toes only just touch the ground. I'm not thinking this is safe to ride around London.

When road bikes had top tubes parallel with the ground, if you could not stand over the top tube (i.e. out of saddle, straddle the top tube, put both feet on the ground), that was an indicator that the frame was too big. That's no longer true, since almost all frames have sloped top tubes.

On performance bikes, it is pretty common to sit on the saddle and be barely able to touch the ground. I can touch it with the tip of my toe, and I think my saddle height is a bit lower than average.

I am not sure exactly what your quote means. Please consider clarifying. What does standing on the bike, off the saddle mean? If your toes can't touch the ground, are you actually sitting on the bike's top tube? (If the latter is true, that bike is probably many sizes too big.)

If I change the wheel size, rims, to a smaller size will this lower the height of the bike?

This will lower the height of the bicycle. Unfortunately, bikes with rim brakes can't take smaller wheels - there is no means to lower the brakes. Bikes with disc brakes should be able to do this. However, you would also change the bike's handing away from the design parameters. Notably, I think you will decrease the bike's stability...

I measured the rims diameter 25 inches. If I got smaller wheels would this work?

I'm actually not sure what you measured as 25". There is an older wheel size called 26". The effective rim diameter, i.e. 2x the distance from the center of the hub to the bead seat (not to the top of the rim sidewall, this is where the tire beads sit) is 559mm, or about 22 inches. A 29er rim (same diameter as road bikes) has an effective diameter of 622mm or 24.5 inches. I am guessing you might be measuring from one end of the tire to another. If you have a disc brake bike, then I guess you could put in 26" wheels, which are an older spec, if you can find one which fits in your bike (e.g. does it have quick releases or thru axles; the latter will be a big problem) However ...

I've lowered the seat as far as it can, and the handle bars too.

If you need to lower the seat all the way, then yes, the bike is very likely to be too big. However, you can't actually fix this with a smaller wheel size. That changes how low you are to the ground. It does not change the length of the bike, or the distance between the bottom bracket and the saddle, which affects your leg extension when pedaling. Many casual cyclists set their saddles too low, and they won't be able to generate as much power.

So, why did you lower the saddle? Is it because you have trouble reaching the pedals at the bottom of the pedal stroke? That means the bike's too big and can't be fixed. If you just lowered the saddle because you can't touch the ground, that wasn't what you want to do.

Answer 2

Being able to touch the ground while sitting on the saddle is not a criterion. When you stop you are supposed to move in front of the saddle. If you are in front of the saddle and unable to stand on the ground because your genitals are hitting the top tube then your frame is certainly too big.

Saddle position should be set for the most comfortable and efficient pedaling motion. This usually means that your leg is almost fully extended in the lowest pedal position (6'o clock) so it doesn’t rise too high in the highest position (12'o clock).

Changing to a smaller wheel diameter would create all kinds of issues. There are only a few mountainbikes with disc brakes which are designed for it.

Answer 3

No - this bike cannot take smaller wheels

Based on the photo - you have rim brakes on an 80's or early 90's road bike. The height of the pads has a few millimetres of adjustment, but not enough to go from a 700c sized wheel to any reasonable smaller size.

It is possible to get caliper brakes with longer reach, but their performance drops off rapidly because of leverage. These are good for a 630mm--> 622mm rim swap, but you're not going to get down to a 584mm rim, which is also known as a 27.5"

If the bike had disk brakes, then this would be more feasible. But this frame cannot take disk brakes and it is not build to have them retrofitted.

Your only real option is to buy a smaller bike frame that fits you, and sell this gorgeous old raleigh. Sorry if that's bad news.

Answer 4

The main thing to check is whether, when sat on the saddle, you can easily reach the pedals with a flat foot at the bottom of the pedal stroke. By "easily", I mean without locking your knee out completely straight. Ideal bike fit means having a very slight bend in your knee even when your foot on the pedal is in the lowest position.

So what if the bike doesn't fit?

Well, it can be uncomfortable and, over long rides, lead to joint or muscle pain that might need physio work to fix.

It might also be unsafe if you can't easily control the bike in the situations you'll be riding. In London you may need to stop suddenly or swerve to avoid other road users, etc.

However, plenty of people do ride bikes that are too large or small for them.

At the end of the day you're the best judge of whether the bike is good enough for you to ride safely. I suggest checking this out in a safe area like a park when few people are around.