Author Topic: 26" or 700C  (Read 1515 times)

26" or 700C
« on: 24 January, 2021, 02:11:29 pm »
I'm planning on building a new tandem this year around an S&S coupled frame. As I'll be having the frame built the world is my oyster with regards to spec. We currently have 26" wheels with Marathon Supreme 1.6" tyres. Without wishing to start a debate along the lines of "I use x size and they are better...", and I've read all the technical articles regarding contact patch etc. What I would really like to know is is there anyone here who has used both sizes WITH the same tyres who can comment on any perceivable performance differences? I am fully aware of the advantages of smaller wheels (weight, strength, lower gearing etc) so is there any good reason for going over to 700C. I might add that I'm 6'1" so there are no issues to do with my size that would favour a smaller wheel. The tandem will be used for day rides and loaded touring.

Thanks, Ian

Re: 26" or 700C
« Reply #1 on: 24 January, 2021, 02:21:30 pm »
My experience (not tandems) is that the same tyres don't perform in the same way.

I used to ride on 1.5" x26 paselas. Got a 700c bike and bought the same tyres, but 28mm width.
didn't perform anywhere near the same way. Less grip, wore out quickly.

There probably isn't much if any difference if you run the same tyres, same width, same pressure.

I found 700c did roll better, a tad less vibration.
<i>Marmite slave</i>

Re: 26" or 700C
« Reply #2 on: 24 January, 2021, 02:22:36 pm »
700c.  26" is becoming marginalised as MTBs adopt 29" (which is 700c with a fat tyre) or 27.5" (which is 650b with a fat tyre).  Tyre choice has always been poor for 26" road (I had a Thorn Nomad for 10 years) and will get worse.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

LittleWheelsandBig

  • Whimsy Rider
Re: 26" or 700C
« Reply #3 on: 24 January, 2021, 02:26:32 pm »
rogerzilla has the right answer. 650B if you want a smaller overall wheel diameter.
Wheel meet again, don't know where, don't know when...

Re: 26" or 700C
« Reply #4 on: 24 January, 2021, 04:17:10 pm »
rogerzilla has the right answer. 650B if you want a smaller overall wheel diameter.
Limited choice of suitable road tyres in 650B for a tandem. Likewise limited choice of rims if you want rim brakes (I do).

Re: 26" or 700C
« Reply #5 on: 24 January, 2021, 04:19:39 pm »
My experience (not tandems) is that the same tyres don't perform in the same way.

I used to ride on 1.5" x26 paselas. Got a 700c bike and bought the same tyres, but 28mm width.
didn't perform anywhere near the same way. Less grip, wore out quickly.

There probably isn't much if any difference if you run the same tyres, same width, same pressure.

I found 700c did roll better, a tad less vibration.
Comparing a 1.5" (38mm) with a 28mm tyre will show a noticeable difference in performance but tells us nothing with regard to wheel size :)

Re: 26" or 700C
« Reply #6 on: 24 January, 2021, 04:21:15 pm »
700c.  26" is becoming marginalised as MTBs adopt 29" (which is 700c with a fat tyre) or 27.5" (which is 650b with a fat tyre).  Tyre choice has always been poor for 26" road (I had a Thorn Nomad for 10 years) and will get worse.
I don't really understand that. Schwalbe do an excellent range of road tyres suitable for tandems in 26" (and 700C).

Kim

  • Timelord
Re: 26" or 700C
« Reply #7 on: 24 January, 2021, 04:26:56 pm »
I don't think the 26" road tyre is going to disappear any time soon, but most of the choice seems to be at the 'touring' end of the tyre spectrum.
Careful, Kim. Your sarcasm's showing...

Re: 26" or 700C
« Reply #8 on: 24 January, 2021, 08:25:33 pm »
I've always preferred the handling of 26" wheels with  good tyres - Though I've not ridden a 700c wheeled tandem since the late 90's and that was just on a short club run...  We can all speculate on availability & tyre choices  for 26" wheels, but I am just as concerned as to the diminishing options for rims designed for rim brakes, as the bike industry jumps on the disc brake bandwagon.

Re: 26" or 700C
« Reply #9 on: 02 February, 2021, 09:15:23 pm »
Having owned two 26” and one 700c wheeled tandems I have defiantly come to prefer the 26” wheel for tandem use.  I’ve had a few occasions on twisty, poorly surfaced country lane decants were the folks on solo bikes just fell away behind us, the grip and confidence you get from a good 26” x 50mm touring tyre is superb.

Of course things move on and there are now some really good light weight wide tyres available in 700c & 650b so having to choose between a 700c x 32mm tandem set up or a 26” x 42/50mm set up is now a null point.

On the subject of 26” tyres we’ve used Panaracer Pasela’s, Marathon Supreme’s, Marathon Duremes and on the odd occasion Marathon XR’s.  The Duremes are my favourite tandem tyre, managed to get a couple of pairs when Spa were selling them off at £10 each. 

If I needed new tyres today and were not constrained by price I’d probably try a set of Rene Herse / Compass tyres, it would be interesting to see if they are as good as some folks report.

Re: 26" or 700C
« Reply #10 on: 02 February, 2021, 09:50:54 pm »
Having owned two 26” and one 700c wheeled tandems I have defiantly come to prefer the 26” wheel for tandem use.  I’ve had a few occasions on twisty, poorly surfaced country lane decants were the folks on solo bikes just fell away behind us, the grip and confidence you get from a good 26” x 50mm touring tyre is superb.

Of course things move on and there are now some really good light weight wide tyres available in 700c & 650b so having to choose between a 700c x 32mm tandem set up or a 26” x 42/50mm set up is now a null point.

On the subject of 26” tyres we’ve used Panaracer Pasela’s, Marathon Supreme’s, Marathon Duremes and on the odd occasion Marathon XR’s.  The Duremes are my favourite tandem tyre, managed to get a couple of pairs when Spa were selling them off at £10 each. 

If I needed new tyres today and were not constrained by price I’d probably try a set of Rene Herse / Compass tyres, it would be interesting to see if they are as good as some folks report.
Thank you for chipping in. I've been using 1.6" Supremes (the latest iteration HS469) and like them. I wonder why you prefer the Duremes which are heavier, particularly as you are leaning towards Compass tyres which I would imagine are more like Supremes.
 

Re: 26" or 700C
« Reply #11 on: 02 February, 2021, 10:59:05 pm »
My Orbit Tandem is fitted with twin bosses  so you can fit  700c for road work , or  26" for heavy touring and a rear disc. It might  be a good idea to future proof a custom build . I can see good quality 26" road tyres going the same way as  650c , I have a trike fitted with them bloody expensive & difficult to get if you want a plus 23mm size .
 Thorn do a reversible mount for some of their frames . I know Geoff booker  ( Trykit ) love's his 650b that are fitted to his tandem trike .   
Four wheels move the body, two wheels move the soul  three wheels Nurses !!!

Re: 26" or 700C
« Reply #12 on: 03 February, 2021, 08:05:17 am »
My Orbit Tandem is fitted with twin bosses  so you can fit  700c for road work , or  26" for heavy touring and a rear disc. It might  be a good idea to future proof a custom build . I can see good quality 26" road tyres going the same way as  650c , I have a trike fitted with them bloody expensive & difficult to get if you want a plus 23mm size .
 Thorn do a reversible mount for some of their frames . I know Geoff booker  ( Trykit ) love's his 650b that are fitted to his tandem trike .
As it happens our Orbit Tandem has the same feature of twin brake bosses at the rear. But to use two different wheel sizes would require to sets of front fork, one for each size of wheel, or one with long fork blades that would accept both sizes of wheel either with disc brake mounts or two sets of bosses (although IMO opinion it would look all wrong with a 26" wheel fitted). However one thing I don't like about our Orbit is that the chainstays appear to very long and out of proportion fitted with 26" wheels. Secondly fitting mudguards is a bit of a fiddle to get 26" guards to fit neatly into a space designed for 700c. The other thing that I'm unsure about is how the handling of the bike would be affected by changing the wheel sizes. It would appear that Orbit designed the frame to take either a 26" or a 700c wheel at the rear and I assume they would have supplied the appropriate length front fork for the matching front wheel. This however would change the steering geometry, the longer fork and bigger wheel giving a shallower head angle and consequently less trail. I wonder if this is why they abandoned the idea?

LittleWheelsandBig

  • Whimsy Rider
Re: 26" or 700C
« Reply #13 on: 03 February, 2021, 09:06:52 am »
Changing unsuspended fork length on a tandem between 559 and 622 makes little difference to head angle, particularly if the 559 tyres are much fatter than the 622 tyres.
Wheel meet again, don't know where, don't know when...

Re: 26" or 700C
« Reply #14 on: 03 February, 2021, 05:25:17 pm »
Changing unsuspended fork length on a tandem between 559 and 622 makes little difference to head angle, particularly if the 559 tyres are much fatter than the 622 tyres.
You make a very fair point and one that has got me using my school boy Pythagoras! Looking at typical touring bike forks the difference in length between their 26" and 700c forks is around 14mm to which we need to add the increase in rim radius of approx 31mm minus any decrease in tyre width (say 5mm) giving an increase in height at the fork crown of 40mm, which equates to difference in head angle of approx 1.3° which I don't think is insignificant. In fact it reduces the trail by about 8mm, approx 15%. To what extent that would have any significant effect on the steering I wouldn't like to say. For the same tyre width (which would probably be the case for my usage the difference would even greater). Any frame builders here like to comment?  :)

LittleWheelsandBig

  • Whimsy Rider
Re: 26" or 700C
« Reply #15 on: 03 February, 2021, 06:34:33 pm »
559 forks usually allow a lot more tyre clearance than 622 forks. Traditionally, 559 MTBs could be fitted with skinny 700C road wheels and tyres, sometimes with mudguards.

You are changing both front and rear wheel, so the difference in radius between 559 and 622 is irrelevant. The whole bike moves up and down, just like changing the tyre width.

The only real difference is the difference in fork length. Your assumption for that is 14mm, a very small percentage of a tandem's wheelbase. I will let you run the numbers yourself to find the angle difference. The very rough rule of thumb for solos was 1 inch = 1 degree.

A good designer will use different fork rakes for 559 and 622 forks and for different cycle types. You have assumed the same fork rake for both but you are talking about a custom tandem. Unless you are using carbon forks, you get to choose the amount of rake on your steel fork, so you can choose whatever trail value you want. Generally tandems steer better with about 10-12mm less trail than a solo with the same head angle. Whether a tandem runs a steeper head angle or a more raked fork (or a combination of the two) than a solo is up to you.
Wheel meet again, don't know where, don't know when...

Re: 26" or 700C
« Reply #16 on: 03 February, 2021, 07:49:59 pm »
559 forks usually allow a lot more tyre clearance than 622 forks. Traditionally, 559 MTBs could be fitted with skinny 700C road wheels and tyres, sometimes with mudguards.

You are changing both front and rear wheel, so the difference in radius between 559 and 622 is irrelevant. The whole bike moves up and down, just like changing the tyre width.

The only real difference is the difference in fork length. Your assumption for that is 14mm, a very small percentage of a tandem's wheelbase. I will let you run the numbers yourself to find the angle difference. The very rough rule of thumb for solos was 1 inch = 1 degree.

A good designer will use different fork rakes for 559 and 622 forks and for different cycle types. You have assumed the same fork rake for both but you are talking about a custom tandem. Unless you are using carbon forks, you get to choose the amount of rake on your steel fork, so you can choose whatever trail value you want. Generally tandems steer better with about 10-12mm less trail than a solo with the same head angle. Whether a tandem runs a steeper head angle or a more raked fork (or a combination of the two) than a solo is up to you.
You are of course quite right about the difference in fork length being the only factor affecting steering angle - I wasn't thinking straight! And as you imply any change in trail due to change in head angle can be compensated for with a change of rake.

Re: 26" or 700C
« Reply #17 on: 04 February, 2021, 09:01:59 pm »

[/quote]
Thank you for chipping in. I've been using 1.6" Supremes (the latest iteration HS469) and like them. I wonder why you prefer the Duremes which are heavier, particularly as you are leaning towards Compass tyres which I would imagine are more like Supremes.
[/quote]

That's a fair observation.  I’ve been interested in trying the Rene Herse / Compass Rat Trap 26” tyre for a while, if I were to buy a pair I’d probably use them on the Surly LHT and maybe try them out on the tandem after that.  The fact is though that I’m unlikely to be buying them any time soon as I’ve got unused Supreme’s and Duremes squirreled away.

I’ve been happy running 50mm Supreme’s on the tandem but tend to prefer the Dureme’s as they offer a bit more grip when riding on lose surfaces which we often find ourselves doing.  Despite the extra weight and tred of the Dureme they seem to roll just as well too. 

Re: 26" or 700C
« Reply #18 on: 05 February, 2021, 07:53:32 am »
That's a fair observation.  I’ve been interested in trying the Rene Herse / Compass Rat Trap 26” tyre for a while, if I were to buy a pair I’d probably use them on the Surly LHT and maybe try them out on the tandem after that.  The fact is though that I’m unlikely to be buying them any time soon as I’ve got unused Supreme’s and Duremes squirreled away.

I’ve been happy running 50mm Supreme’s on the tandem but tend to prefer the Dureme’s as they offer a bit more grip when riding on lose surfaces which we often find ourselves doing.  Despite the extra weight and tred of the Dureme they seem to roll just as well too.
Out of interest have you tried 1.6" Supremes? I've wondered about using the 2" Supremes but am unsure of the difference in performance between the two sizes.

Re: 26" or 700C
« Reply #19 on: 20 February, 2021, 10:34:46 pm »
I have had a set of to 1.6 Supremes but it was a long time ago and not on the tandem.

The 50mm Supreme does seem to quite a bit narrower than stated once on the rim, if I remember I'll measure them tomorrow.