A Gravel Bike

Cannondale Topstone 105

The Cannondale Topstone 105 Alloy is a gravel bike by Cannondale, a subsidiary or brand of the Canadian conglomerate Dorel Industries, manufactured in Taiwan. The frame is an aluminium alloy. This is what it looks like

Cannondale builds it in 5 sizes that it calls XS, SM (small), MD, LG, XL. I bought the medium size, which means, according to the datasets used by Bike Insights:

  • The seat tube is 505 mm long;
  • The “effective” (horizontal) top tube length is 561 mm;
  • Stack 579 mm; Reach 385 mm – Average for category;
  • Trail: 63.7 mm;
  • Chainstay (horizontal) 423.4 mm.

The 2019 Cannondate Topstone 105 Alloy has a profile at Bike Insights. It is neutral on the upright/aggressive scale. It is a neutral mid trail bike.

The Cannondale Topstone 105 shipped with tubeless ready WTB ST i23 TCS wheels and 700c x 40 (ISO 40-622) WTB Nano TCS tubeless ready tires. The tires are knobby, like many mountain bike tires and cyclo-cross tires. 700c x 40 may the largest/widest tires that run on this bike.

The crankset was FSA, with 172.5 mm crank arms, and 46/30 rings – a “compact” road bike crankset. The brakes, shifters, 11 cog cassette, and derailleurs were Shimano 105. The largest cog on the rear cassette was 32 teeth; lowest possible gearing was 30 to 32. The lack of more climbing gears is a flaw of this and other production gravel bikes.

There are eyelets at the drop outs for the rear wheel and on the seat stays to mount a rear rack, but the chain stays are short. There are eyelets behind the bottom bracket, on the seat stay bridge and at the rear dropouts for a rear fender. The frame has several eyelets for bikepacking bags and accessories. It can be fitted with some touring and bikepacking gear. The stays are widely separated for wide tires and disc brakes. Some racks and fenders can be fitted.

The carbon fiber fork lacks the front facing mounting point at the fork crown found in bikes with rim brakes. There is a rear facing eyelet at the fork crown for a fender with an L-bracket. It has no eyelets on the outside of the fork blades. It provides one eyelet on the inside of each fork blade 150 mm above the axle drop-out. The limits the options for front racks, and bags:

  • A demi-porteur randonneur rack requires a front-facing eyelet at the fork crown and eyelets above midfork to mount the cantilevers;
  • A low rider front rack requires eyelets at the drop-outs;
  • The cable routing along the drop bars limits the options for proprietary mounting braces (eg. Arkel, Salsa); the space between the drops and brake levers

Rack

I tried to use the Tubus Logo Evo touring rack that I had used on my Trek. It fit on the wider chainstays (longer rear axle) of a disc brake bike with modification of fit kit parts. I was able to install a Tubus Vega, which can carry a trunk bag. The point is to carry some tools, an inner tube, some clothing and little food. The rack legs and the bolt heads for fender stays interfered with the rotation of the thru-axle handle. The thru-axle may have to removed to remove the wheel for maintenance and repair. The handle may be removed with a 4 mm Allen wrench, but when that is done, a larger (e.g. 12 mm) fixed wrench (combination or open end) will be needed to release the axle. An after-market rear axle (Robert Axle Project) that can be removed using a 6 mm Allen key was part of the installation of the rack.

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