Converting a Hybrid with 700c to 26" wheels?

[Monkspeed]

I want to change the 700c wheels on my wife's hybrid Raleigh Urban 1 to 26" wheels.

It currently has Tektro Cantilever brakes, and has some mounts (i think) for the other type of brakes, but with a 26" wheel it would need a hell of a drop.

I can't figure out what to do with the brakes, I am thinking to get wheels with disc brake mounts and convert it to disc brakes, but I'm not sure if the caliper has a mount on the frame. It's got two pairs of holes on the rear part of the frame, but only one pair on the front forks. Is there a converter or a way to convert it to disc brakes?

Reason I want to modify the bike is my wife is very short and her feet cannot touch the floor unless the seat is really low, of course then the seat is too low for her to make the best use of her leg when pedalling.

Many thanks.



EDIT: Just to mention that I've done loads of searching and 99.9% of the time its someone wanting to convert it the other way around. Sheldon brown has something on converting from 700c to 650b (or something like that anyway) but I would like to go smaller.

 

[RecordAceFromNew]

If this is the bike, I can't see disk mounts for either frame or forks... The two holes near the rear axle are for mudguard/rack. Perhaps some photos of the holes you mention will help.

 

[mickle]

I don't understand why she has this problem - unless the BB is unduly high.

If you fit smaller wheels you run the risk of knocking the pedals on the ground unless you fit a corespondingly shorter set of cranks. It's likely that you'll do funny things to the front end geometry too.

Try moving the seat back as far as it'll go and down - kind of rotating it around an radius whose centre is the BB. Then adjust the bars to fit. Would I be correct in thinking that the saddle is as far forward as it'll go so she can reach the bars?

 

[Monkspeed]

If this is the bike, I can't see disk mounts for either frame or forks... The two holes near the rear axle are for mudguard/rack. Perhaps some photos of the holes you mention will help.

Yep thats the one, I had an inkling they were for a rack etc but I was hoping it was a caliper mount, Ah well.

I don't understand why she has this problem - unless the BB is unduly high.

If you fit smaller wheels you run the risk of knocking the pedals on the ground unless you fit a corespondingly shorter set of cranks. It's likely that you'll do funny things to the front end geometry too.

Try moving the seat back as far as it'll go and down - kind of rotating it around an radius whose centre is the BB. Then adjust the bars to fit. Would I be correct in thinking that the saddle is as far forward as it'll go so she can reach the bars?

If you check this picture out that RAFN lined to, you can see the BB is indeed pretty high.

What happens if I move the seat all the way back?

 

[boydj]

I suggest your wife gets used to simply sliding forward off the saddle as she comes to a stop - this will very quickly become a natural movement. Being fairly short myself, that's the only way I can touch the ground and with 32 sets of lights on my commute I do need to touch the ground frequently.

That way you can have the saddle set for efficient pedalling, and no need for a tricky conversion

 

[mickle]

What happens if I move the seat all the way back?

Back and down, around a radius whose centre is the bb. It retains the saddle to pedal distance for efficient pedaling but moves the saddle closer to the ground.

 

[RecordAceFromNew]

Is it a confidence issue? I think pretty much everybody who has the saddle at the right height can only reach the ground tip-toed when sitting on the saddle (and leaning over).

A common rule of thumb for correct saddle height is heel on pedal at its bottom stroke with leg straight. Since the average crank arm length is 170mm, that means the heel is 6 inches below the bb axle. However bb axle might on average be say 11 inches above ground (13 inches not unusual for mtb's), so tip-toe is pretty much unavoidable, and perhaps not even achievable if one has small feet.

 

[Muddyfox]

Why dont you just sell the bike and buy another bike with 26" wheels on it and save all the faffing around with swapping all the brake system over ?

 

[RecordAceFromNew]

The issue is bb height. Most 26" wheel bikes have bb higher than 700c wheel bikes, because they are supposed to cater for rougher terrains and therefore requiring more pedal/ground clearance. For short riders perhaps 24" wheel bikes designed for teens might help, but am only guessing.

As Mickle said moving the saddle back/lower will help, but to maintain pedal reach I think it will have to move back 2 inches to drop an inch.

 

[Monkspeed]

Yes it is a confidence problem, she is tip-toed already with the seat on minimum. She looked good on a Triban Junior road bike, I think that has 24" wheels so RAFN you are probably right.

I suppose it's my fault really, I could have perhaps researched it a bit more before buying a bike for her, but when you buy a bike with a 14" frame you assume that the wheels will be in-keeping with the frame size. Why make a frame so small but with such massive wheels on it?

Anyway looks like I will have to find her a new bike.

Cheers.

 

[mickle]

A new bike will not fix the problem. This is a classic case of needing to find a compromise between the mutually exclusive desires for a saddle position high enough efficient pedalling and low enough to instil confidence in a novice. The solution's pretty simple: set the saddle as high as she is happy with and slowly raise it over a period of weeks as her mileage and confidence increases.

This might be useful..
And this..

And perhaps even this..



Oh, and this..

 

[Monkspeed]

A new bike will not fix the problem. This is a classic case of needing to find a compromise between the mutually exclusive desires for a saddle position high enough efficient pedalling and low enough to instil confidence in a novice. The solution's pretty simple: set the saddle as high as she is happy with and slowly raise it over a period of weeks as her mileage and confidence increases.

This might be useful..
And this..

And perhaps even this..



Oh, and this..

Thanks Mickle, some good reading material there

 

[Night Train]

However, if you are determined to change to smaller wheels then you could use drum brake hubs. The reaction arms are clamped onto the fork and chainstay and the cables will need to be longer and maybe re-routed at the rear.

I have a pair of Sturmey Archer 70mm drum brake hubs with 26" rims that will possibly go on my hack. The rear wheel has a nicer condition cassette on it then the one I have too.

You should be able to get the same with 90mm drums which will be a bit better more effective with 26" wheels.

 

[Monkspeed]

However, if you are determined to change to smaller wheels then you could use drum brake hubs. The reaction arms are clamped onto the fork and chainstay and the cables will need to be longer and maybe re-routed at the rear.

I have a pair of Sturmey Archer 70mm drum brake hubs with 26" rims that will possibly go on my hack. The rear wheel has a nicer condition cassette on it then the one I have too.

You should be able to get the same with 90mm drums which will be a bit better more effective with 26" wheels.

Sounds interesting, where can I get them from?

Cheers.

 

[Night Train]

Sounds interesting, where can I get them from?

Cheers.

I found mine on Ebay, sold seperately from the same seller, with Schwalbe City Jets and paid very little for the pair.
Sometimes bargains can be had!

You can get the drum brake hubs for front and rear and then have then laced into rims, I did it myself for my folder so it isn't difficult if you want to have a go.
Rear Hub
Another one
And another
Front hub
A 90mm front hub, better!
Another one