bikeinxs

The drop bar conversion on my old Cousin It is coming along but I'm seriously thinking about changing direction a bit. Rather than stick with 26" wheels I'm considering moving to 650B. I was about to order White MI6 hubs with 26" Aeroheat rims, but I'm thinking of switching to the 650B Synergy rims (36 hole). There's lots of clearance on the front and back (in fact there is room for 700c rims with about a 35 mm tire). I've got a Cannondale Fatty fork so I'll be running disc brakes on the front (the new Shimano calipers with ICE rotor). I haven't taken a torch to the frame so it's still canti's on the back. If I go to 650B I'll need to put Paul's Moto BMX brake for the pad adjustment. The primary use will be gravel roads and fire trail. Planning on riding D2R2 this August as well. We're a just under 300lb team.

Any thoughts before I place my wheel order?

waynesulak

I converted an Santana Arriva 700C bike to 650B and love it. I paid a local single bike frame builder move the canti studs and purchased a 60mm rake fork. Our current ride is a road only bike. We have about 7,000 miles on it. We run Grand Bois Lierre tires at 70-80psi. The bike is pictured with 42mm Hetre tires but there was not as much clearance as I like. Team weight 280-290 lbs.


I considered using a 26" inch wheel tandem for the conversion but did not have one to try the wheels size for fit. I am interested to see how the Paul's Moto brakes work out. Please post results if you convert. I may do a 26" wheel tandem conversion next.

swc7916

Would R+E's BigSqueeze brakes provide the pad adjustment you need?

syburgh

Be careful: IME the Synergy extrusion is not really up to the rigors of a wide tire at the high pressures needed for tandem. I converted our 700C tandem to Synergy + Grand Bois Hetre, which we run at 80psi (450lb team). We've broken three Synergy rims in less than 12 months riding on occasional gravel roads (mostly roads, probably about 3k miles). The wheels fail by going severely out of true after each ride (need lots of truing every dozen miles) and then eventually the rim cracks at some random time of the day or night (sounds like a gunshot). We have had the same experience with US and Australian-made 36h O/C rims. Our wheels were built by one of the more internet-famous builders of tandem wheels.

Stoker loves this setup and would not consider going back to narrow tires, so we are on Synergy #4 and #5 now (both are fine with <1k miles)

I've enjoyed Synergy rims on my single bikes for many years (and miles), but am looking forward to 36h 650B downhill rims for the tandem (our frame is ready for discs). Considering Pacenti DL31 and Velocity Blunt for next step, but neither is compatible with rim brakes.

waynesulak

Our 650B tandem had the same issues with 38mm tires at 75-80 psi. I got some of the rims replaced by Velocity and they continue to say the rims will work. We have replaced four rims all rebuild cost out of pocket. Mine cracked along the middle of the brake track within 1,000 miles.

Had both sets rebuilt with Velocity A23 rims. These rims are "tubeless ready" which means they have a much shorter rim wall and shallower well which hopefully will make them resist outward force of the wide tire. I did some calculations and slightly shorter unsupported rim wall dramatically increases the strength at the bead to resist for wide tires. I have only a few hundred miles on the wheels. They are much more difficult to mount tires on due to the shallower well between the rim walls. Hopefully they will work out.

The A23 is not listed as 650B on the Velocity web site but Longleaf bicyles ordered a special run and has 32 & 36 650B rims for sale. They also carry 40 hole 650B rims of some variety if you have some older hubs

Also bought some heavier Velo Orange rims to give a try should the A23s crack.

waynesulak

These 26" wheels look like an option rather than converting to 650B

https://www.compasscycle.com/tires_comp_26_175.html