Bicycle Mechanics - Switching from 26" wheel to 27", brake Qs

I have tandem that came w/ 26" wheels. I have a pair of 27" wheels that I'd like to use. The wheels fit in fine, but the problem is that the brake bosses are too low. Are there any ways to address this? Are there brakes with long arms that allow the pads to slide up?

Try an email to Tandems Unlimited at
tandems@mindspring.com for further info.
Steve

Also do you mean 700Cs? If not use 700Cs they will be a bit closer to the bosses.

Also do you mean 700Cs? If not use 700Cs they will be a bit closer to the bosses.


Yes, they're definitely 27" wheels and not 700c. I'm sending an email to Tandems Unlimited. I'll post whatever reply they give me. I talked to my LBS and their only suggestion were brakes made by a company called Marinovative. Apparently, they had really long arms that you could slide the brake pad up and down. Unfortunately, I think they're out of business.

ebbet

I am at work now but I will try to post a photo of an aluminium "U" that I made to put in new, higher bosses. I utilised the old bosses as well as the horizontal part of frame above the wheel to attach the "U" to the frame. I then turned new bosses that screws into the "U" a little bit higher in the approprate place. I now have Shimano XT V-brakes on the back of the tandem where I used to have a very old, heavy and ineffective centrepull brake. Feel free to contact me at tandem4@mweb.co.za or hendrikp@kprsa.co.za if you need more information.

Keep those wheels spinning!!!!!

Big H

I'm surprised that the 27" wheels will fit-have you checked clearances everywhere?

I'm also wondering why you would want to switch from a common and current size wheel to something that is about 20 years obsolete. I'm not even sure if tires suitable for a tandem application are even still made in 27" sizes.

If you were to find an extra-long brake arm, you likely soon find out just what torque can do to a boss. The longer a lever arm (brake arm) you have, the more torque is applied to the base. I'll bet the bosses bend and snap off quite quickly, especially with the weight of 2 riders to stop.

If you seriously want to go through with this, the only safe way to change the mounting position of your bosses is to take it to a framebuilder.

I'm surprised that the 27" wheels will fit-have you checked clearances everywhere?

I'm also wondering why you would want to switch from a common and current size wheel to something that is about 20 years obsolete. I'm not even sure if tires suitable for a tandem application are even still made in 27" sizes.

If you were to find an extra-long brake arm, you likely soon find out just what torque can do to a boss. The longer a lever arm (brake arm) you have, the more torque is applied to the base. I'll bet the bosses bend and snap off quite quickly, especially with the weight of 2 riders to stop.

If you seriously want to go through with this, the only safe way to change the mounting position of your bosses is to take it to a framebuilder.

I put both 27" wheels on and the clearances are fine - no toe overlap or frame rubbing. I got a great deal on the tandem (a Burly Zydeco - or something like that) at SF Veloswap. But the wheels on it are pretty cheap. They look like they came off some department store bike. So...I had an extra set of 27" wheels that were looking for a home. Plus, my current understanding is that these biggers wheels will allow you to reach a faster top speed.

Here's what Tandem Unlimited said:

"The difference between a 26" tire (actual rim diameter ~559mm) and a
700c
(622mm) or a 27" (630mm) is too great to take up with any brakes
available
today. If it's a steel frame, a qualified frame builder can move the
brake
bosses.

Another option -- tho' not highly recommended -- is to swap wheels to
an
internal brake-hub front wheel and a rear wheel that is threaded for a
drum
brake."

Unless you have double-wall 27s, the 26s are probably stronger wheel wise. Also, if the tandem has modern compentry, the drivetrain isn't going to be compatible anyhow... Just gear it higher if you want to attain more speed.

Paul makes the MotoBMX brakes. They are designed to let you use a larger wheel size then normal, and according to the website will work for converting from 26" to 700c so I'm guessing 27" will probably work too.

http://www.paulcomp.com/frmbk.html

Considering the two substantive responses: Dave
Stohler and Tandems Unlimited it sounds like you
need to stay with the 26" wheels. The alternatives are
more expense than the frame justifies. The suggestion
of an outboard "U" bracket of aluminum might work and
if you are handy with metal fabbing, it is cheap and
worth a try. It might be too flexible though, only way to
tell would be to try it (per BigH). In the rear the brake force would push the U bracket toward the frame, but
in the front the force would be away from the frame.
Steve

Hi, here is some photos of a conversion I made on the tandem. It has been working for a year now with no maintenance or repair.

Seems it did not work @!@$%!@$*!(

Another one

^&%$%#$*%$)#&#@ Drat!!!!!