robertorolfo

So my 1982 Lotus Unique, which is my bad weather commuter, originally came with 27inch wheels. In an effort to improve the breaking, I "converted" it to 700c using some narrow (15mm internal) rims I had lying around, and some Tektro 559 dual-pivot long-reach calipers. The bike rides pretty well with this setup, but I have tons of clearance to work with and I'd like to make it a little more comfortable.

I've been reading about 650b conversions, and I was about to take the plunge, but my calculations seem to show that even the long-reach Tektros won't be long enough (the pad holders are about halfway down the slots with the 700c tires on, and according to the sources I've read I would need another 19mm to work with). That would mean another set of ridiculously long calipers, and so far I've only seen some flimsy looking "beach cruiser" types.

Do you guys think I would be better off simply buying (new or used) a wider set of 700c wheels? I was thinking 19 or 21mm internal width, so I can go pretty much as wide as the frame and fenders will take? If it matters, I'm currently running downtube friction Shimano 600 Arabesque, so it should be fine with anything 9 speed or below.

Thoughts?

skinny matt

I think wider 700c is a better option than 650b. The longer those calipers get the more performance degrades. Wider rims would be ideal but might not be absolutely necessary depending on what you want to achieve. How wide are your tires now?

ascherer 

I've just put Compass Bon Jon Pass 35mm tires on my wife's 1984 Lotus Eclair and she immediately reported it being a much cushier ride than the 28mm something or others that were there prior. Not sure of the rim ID, they measure 19.5 at the brake flats so still fairly narrow.

Robert C

Just another factor to consider, I am unable to find studded commuter tyres for 650b. That may, or may not, be a consideration where you are.

Banzai

That was going to be my point. Depending on where you live, you may want/need winter tires. Winter tire options in 650b are virtually nonexistent. That’s what stopped me from doing a conversion.

rhm

I think you have your answer. To get good braking with 650b you probably need to have the frame modified (have cantilever bosses brazed on). What's the widest 700c tire you can fit? How much wider could you go if you went to 650b? If there is a big difference, that is if you can fit 650 x 42b tires, I'd consider having the frame modified. But if you already have 700c wheels, I don't see how 650b conversion will really make sense.

robertorolfo

Thanks for the feedback, guys.

Yes, I'm definitely leaning this way. Breaking performance is probably top priority for me. Currently I'm running a 25mm on the rear and 23mm up front, because that's just what I had lying around. I know I could go bigger than that on my current rims, but I really want to take a significant step up in size.

Wow, her bike looks great. And yes, if they are measuring 19.5 external, I'd imagine they can't be any bigger than 15mm internal. According to this famous link that everyone references (https://www.sheldonbrown.com/tire-sizing.html#width), that would be over the limit for 15's, but some people claim the chart is a little conservative.

My issue in looking for wheels right now is that most of the wider rims come with 135mm hubs (and I already have to sweat to wedge a 130mm hub in there), or they take a bolt-on freewheel. I haven't searched that throughly yet, though.

That's a good point, but for me personally it isn't too much of a factor.

robertorolfo

Agreed, and that's part of the reason why I was asking. If a 650b tire at the same width as a 700c has a taller sidewall, will the difference in ride be drastically better (more comfortable)? I have no idea, and I have no idea if that make it worthwhile considering the other sacrifices (braking quality).

rhm

A few separate remarks:

1. Don't do anything that compromises your braking power.

2. You can safely assume that an inflated part of a tire has a circular section. Height and width will be the same. That's a correct answer in theory, and though it may be wrong in practice, it's a good place to start. The parts of the tire that are not inflated, such as studs, or a thick tread, distort the proportions a bit. Panaracer Ribmo tires, I've noticed, have a kind of pointy shape, taller than they are wide (I assume this means a fairly thick tread in the center).

3. Wider tires certainly have the potential to be more comfortable, but on a commute, do you really need more comfort? I mean, I really like the 26 x 2.3 inch Rat Trap Pass tires I have on one of my randonneuring bikes; they are fast, and they are comfortable, and I can ride 24+ hours, literally hundreds of miles, without getting that beat up feeling. On a ride like that, every little bit of comfort, especially makes it possible to stay in the saddle for another hour, is a benefit. I can't see why you would need that on a commute.

Wilfred Laurier

If you had to get long reach brakes to use 700C, you will struggle to get any decent brakes to work with 650B. Furthermore, that is going from 630mm diameter rims (27") to 584 mm diameter rims (650 B) - an extra step down in size compared to the normal 700-650 conversion - I would expect pedal strike to be a bigger concern with every mm in wheel size you drop.

If you already have long reach brakes you can almost definitely fit 700X35 tires (or wider), which don't generally need to be inflated very hard, and will provide good comfort. You also don't need to worry about rim width so much - 15mm width rims will work just fine with 35mm tires.

ascherer 

Well, they mounted fine and seem to be quite happy there. I say, if the shoe fits...

I recently built a rear wheel for my International to take a 10-speed cassette using a Sun XCD high-flange that's 130. A bit hard to source, I got mine from VeloDuo in the UK.

Archwhorides 

Suomi A10 is the only studded option I know of and difficult to find https://www.peterwhitecycles.com/studdedtires.php

Robert C

I have seen another knobby design. What I am looking for (before next winter) is a tyre that is more of a street tyre.

golftdi

Peter White has 650b Nokian A10 studded snow teres in 2 sizes - ISO 40-584mm & 54-584mm. https://www.peterwhitecycles.com/studdedtires.php
I plan to get a set of 40s for my Midnight Special next winter.

(Edit: I didn't see the post above mentioned these before I did)

robertorolfo

Well, you are right that I can certainly survive my (pretty short) commute with some discomfort. It's just that I wanted to try something different on this bike compared to my other bikes. Aside from all the wet weather work, it also gets all the super low speed riding around with my GF duties.

And you know how the streets can be in the city sometimes. A few rough patches won't kill me, but I'd like to have a bike that allows me to think about them just a little less.

For some reason, this bike has very good BB clearance. I used clips on all my quill pedals (no straps), and this has always been my only bike that will allow me to ride with the clips facing down and not have them scrape on the pavement (not that I do that often). At first I thought it was the bigger 27" wheels, but it still has this good clearance with 700c wheels on.

Anyway, you guys did a good job and convinced me to just buy a set of 700 X 35 tires and throw them on there. Cheap and easy enough...

So which gumwall/skinwall tires does everyone like best? The Paselas look nice...

Looks nice. I wish I had the time to build a set of wheels up, but it's just not on the cards right now.

chas58

I can think of 3 reasons why 650b won't work. 700x35 Paselas are great commuter tires. Hard to do better. Put as big as you can fit on there - but 35mm makes a pretty good city tire.

If you really want new wheels, get something around 21-23mm internal width and tubeless compatible so you have the option of never having flats again.

Just don't get anything knobby with those downtube shifters. I tried that once, and it really hurt!

noglider 

I considered 650b for my Raleigh Super Course, but @nlerner pointed out there's no need, as I can easily fit fat 700c tires. Remember, larger diameter wheels smooth out bumps better, so there is a compromise when you go to a smaller size wheel. I think fat 700c wheels would be better than 650b. I haven't built the Super Course up yet, but you'll know when I've done it.

On the other hand, there are some very large dual pivot brakes available, and they work better than you might expect. Not enough reason to switch to 650b, but don't decide only because you worry about brakes.

Archwhorides 

This year I've been riding a cycle with 700 x 30 slicks (Gatorskins) in dry weather and another with 650b x 40 studded (Suomi A10) in snow/ice conditions.


Based on this experience compared to prior years, I've been waffling on my preferences:

• for plowed icy streets, I sort of prefer riding the 700 with a 30mm Continental Winter (2 row) studded tires, because they feel much lighter than the wider 650b studded, and the narrower width cuts through snow and slush
• and in nicer weather, the 650b with 47mm WTB Horizons run surprisingly fast and they are super cush on crappy urban roads.

robertorolfo

OK, got a pair of 700 X 35 Paselas on their way to me (they are only $29 each right now at Planet Cylcery, w/free shipping). I'll post pics when I get them mounted. Still hoping to meet up with @noglider one Monday night at the bike co-op.

ThermionicScott 

I think you chose wisely. The chief reason to convert to 650B is when your frame can only fit skinny tires in 700C or 27".

ascherer 

Where's there a co-op around these parts?

noglider 

Andy, for a few months, I've been a volunteer mechanic at Mechanical Gardens in Williamsburg. It's a lot of fun, and although I'm the oldest person there, I feel like I've found my tribe. These folks live on their bikes, and I even rode with them on cold winter days.

It's open Monday evenings and Saturday afternoons. It is always busy. The job is to show people how to fix their bikes, not do it for them. They pay a voluntary contribution for use of the equipment and our time. We also strip and rebuild bikes for cheap sale. So we keep people rolling cheaply while they learn.

Minnesnowtan

Your 27" wheels were ISO 630, the 700c is ISO 622, but 650B is ISO 584. Going to the 700c was only an 8mm reduction in diameter and you saw what a problem that was. The 650B is 46mm less in diameter than the 27" originals. If you really want the little wheels then get a new frame. Orange Velo seems to push that wheel size.

I don't. This stuff costs too much, and a way to reduce costs is standardized parts. 700c/ISO 622 has a HUGE selection of not only tires but tyres as well. Get a 23 to 25mm wide rim and put 32mm tires on it. Vectran breakers are best, so look at Continental "Top Contact II" or Continental "4 seasons" (which are really only 3 seasons in Minnesnowta) for reduced flat problems. Or go with Stans or another tubeless rim, and go tubeless (it's breezy) with Hutchinson Sector tires.

Might as well go for a dynohub and get some excellent lighting plus the possibility of charging a USB device while riding, unless you like to make batteries your excuse for limited distance rides.

Stay 700c. 650B is nice for the frames it is designed for and the little people who ride them. 700c is the current standard and there is no good reason to leave it.

robertorolfo

Yes, I realize how big an overall change it would have been, and I guess I just got caught up in the 'do something different' fever. But you guys have convinced me to stick with 700c (and I agree totally that standardization is best for certain things).

So I'm going to try these 700 x 35 tires on my current wheels, and see how they do. If I eventually want to try wider rims, I'll take that step later (and maybe, hopefully, have time to build them myself).

robertorolfo

Fast update: Despite not having the right sized tubes yet, I had to mount the tires last night because the weather here in NYC has been horrible.

So despite using tubes rated only to 700 X 28, everything went on just fine and my first impression has been very positive. The ride feels super plush and nice, like an old Cadillac, and they don't feel dramatically heavier either. I guess I'll have a better idea after I do my usual ride home.

And I'll try to post some pics tomorrow. Suffice to say, in my opinion, they look great on the bike.