Si’ 700c


There it was: a 48 hole Suzue hub in my very own hands. Complete with bearings, it turned so smooth and was so shiny. Curse the LBS for ordering such a thing. It was calling me, I knew I must resist. But I was weak.

I asked a tandemist friend if he had any extra 48 hole rims, knowing he would say no. He called me the same afternoon, he had two still in the wrapper. They weren’t the type he used on his tandems and offered them for free. No turning back now, MUST BUY THE HUB.

The wheel was laced up 4 cross and ready for practice on Tuesday. I picked up some 4"/102mm cranks and cheap BMX pedals on the way home from work. The only spare 700c tire in my garage was a foldable 700x23c but what the heck, slapped it on and pumped it up to 110psi. I took the 26x2.5 Muni wheel off the Profile frame and put in the 700c, plenty of room for a bigger tire!

Only had time for a spin up the driveway and back, definitely quick. At practice I found it wasn’t that bad after a few runs, really screamed on the straights. Idling came quickly, backwards was do-able and mounting no problem at all. Back at home that evening I tried a mile run around the neighborhood, after ½ mile I had a strange UPD and somehow wedged my foot in the wheel so that the pedal smacked the back of my leg and stuck there. OUCH.

Today I picked up the biggest 700c available at another LBS, a Continental 700x47c/28x1.75. It fit fine in the frame with 9/16" clearance to the crown. The larger tire was a bit heavier but a more comfortable ride. Tried it out on 4 miles of Brier hills, going down hill is the biggest challenge, with the short cranks the control phase on the up-stroke is very brief. I fell off going down on a couple of steeper hills that I was able to handle on the Coker.

Going up moderate hills was not a problem but again steep hills were very different. On the Coker and other uni’s I can either march or do the ½ revolution & pause to get up steep stuff, with this one I had to keep the spin going or I would stall and fall.

So, how long does it take to really get used to the short cranks on the hills? This thing is a gas on the flats but them big hills have me beat so far.

Photos Here

i never really got used to the skidishness of 102’s on a 29er,i just delt with it.if i did it again i think i would go with 110’s.still fast.

(good to see the Profile is still alive,looks like you squeezed the frame a litte though :wink: )

On my 28, I have 110s. (A 28 is only about 3% smaller than a 29.)

I have ridden it with 102s, and it is rideable, but skittish. Super short cranks have this problem: on any uni you can only exert meaningful control on the pedal for a few degrees of the revolution (say 120 degrees?) and when the crank is short, the pedal passes through those 120 degrees very quickly. This means that the slightest mistake when slowing down, idling, or braking on a descent, and the pedal flips past the ‘point of no return’. If you’re unlucky, you fly off the back.

102s are about 7% shorter than 110s, so you get about 7% less torque, but the loss of control is greater than 7% for the reason given above.

I keep my 28 as a pure road machine (except when the devil makes me turn off onto a muddy tack) and I think crank length becomes a safety issue. If you are not 100% confident of controlling the uni in all foreseeable traffic conditions, you shouldn’t ride it on the road. So I took the 102s off and went back to the 110s.

As for hill climbing/descending, you will find that technique, balance and experience will achieve so much and no more. I have noticed that I can now waltz up and down hills on my 28/110 that used to stop me on a 26/150, but there is a limit. If you live in an area with many steep hills, you may need to go for longer cranks - say 125s.

Or learn to ride one footed, and have one crank 102mm long, and one at 125. This will also make it easier to ride across steep slopes, but in one direction only!

For the downhills, I’m pretty sure a drag brake would do the trick. Personally I don’t ride short cranks much, but i have used a brake and it feels just like the hill flattens out. Do your rims have a braking surface? I’m sure you’ve seen these but I’ll post the link anyway. This brake was very inexpensive but surprisingly smooth and effective. To me, short road cranks scream for a brake; it lets you get out of the hill what you put into it with safety.

The reach may give you troubles; this brake was an Odyssey 1999 BMX brake which apparently is one of the few with such a long reach.

700c uni and brake

Hey Steve,

Your ride looks awesome! A while back I was able to order a 52 Conti tire. I looks like you still have plenty of room it you wanted to got for more cushiness. I think that the roll-out distance would be about the same as your 47. Perhaps you could ask at you LBS if they might be able to get one for you. In my case, the LBS had gotten it by mistake and I just happened to be standing there when the owner, cursing all the while, pulled it from the shipping box.

Again, sweet ride!

jagur, that’s not a squeezed frame. Its an hour-glass figure.

Took it out on the local cycle path today. Abby wanted to ride her 16" wheeled bike to a park so we did a 5-6 mile round trip. Perfect uni for chasing a 6 yr old on the flats but the jury is still out on 102’s. If I don’t track down some 110’s I will try the 125’s next time out.

I really like that brake 'ala U-Turn, I’ll keep my eyes open for a brake with a good long reach.

As for one-footed…spot me a few hundred more miles.:slight_smile:

there is plenty of room to drill that fork crown,then you could mount an easy to find long reach calliper(sp?) brake aka.“sidepull”.

dont pull one off my tandem though:-)