bigfudge

I wonder if anyone knows or can calculate the widest possible tyre clearances with a road compact chain set?. I’ve been experimenting with Schwalbe 60mm/2.35in beach racing tyres on a drop bar mtb and think they are wonderful.. Incredibly comfortable! Especially with a load on, and. fast enough on the flat that I’m easily spinning out my 34/11 mtb crankset.

If one used a plate yoke type arrangement by the bb like many of the fat bikes, could you get a tyre like that within a standard road crankset? Perhaps a square taper with a longer axle? Or is clearance always goi g to be an issue?

Ben

WheelNut2

Well, there are a lot of variables here. Wheel size, chainstay length, frame material, BB drop, chainline, hub width, your height and proportions and more all have an effect on the feasibility of this idea. Are you thinking of having a custom frame built for this purpose? It's likely possible, but there might be issues with chain clearance to the tire in the lowest gear if you are using a road drivetrain and wheelset. There may be other compromises that would need to be made to the design to get such large tires to fit with such a narrow crank that you may or may not be willing to accept.

If your curious about the dimensions of a road crank see this document from SRAM: (page 42)
https://www.sram.com/sites/default/f..._2017_road.pdf

If your feeling industrious you could use those dimensions, measure your tire and draw a rough mock up in Google Sketch Up or on a piece of paper.

bigfudge

Cool - thanks. Yes am thinking about a custom... or actually, a DIY project with a friend who's an expert in carbon layup for boats/rigging, and fancies trying a frame.

OneIsAllYouNeed

Theoretically, the maximum tire size for a given crankset or rear hub spacing is determined by the innermost chainline. That's what's driven fatbike hub and crank standards over the years. If you get the chainstay completely out of the way, you can use these combinations:
130mm rear hub with road crankset: 60mm tire
135mm rear hub (142mm TA) with wide road crankset: 65mm tire

Practically speaking, take a look a wide tired road bikes on the market today. They're maxing out at 700c x 45mm or 650b x 54mm because the chainstay needs some space and clearance from the chainring and tires.

wsteve464

As said above road cranksets will limit you to under 2 inches for a tire. Have you considered using a 42/28 tooth SRAM mtb crankset they have a q-factor around 165-170, road is around 145-147. You can get larger after market chainrings on ebay if needed or use a 42 tooth chainring and a SRAM 10 tooth rear cog. With the MTB crankset there is plenty of room for a 2.35 inch tire using oval chainstays a slight crimp on the inside of the stay maybe needed. On a lugged frame I am running a 2.1 inch Vittoria Mezcal 29 front and rear. The front fork is the limiting factor there is plenty of room in the rear for a larger tire.