Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

Bb drop looks all the same

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Old 12-23-18, 11:14 AM
  #1  
mtb_addict
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Bb drop looks all the same

hey yall so i successfully converted my 26" Pacific mtb to fix geared...luving it so far. but it put 1.5" tire so the BB is lowered that got me always worry of pedal strike.

anyway looking for a better bike now...with BB height in mind. i looked at allot. i look at bikes' profile side... i draw a line between both axle...and then i visualize the distance of the BB axis relative to the line. i am surprise that all the different bikes i look at, road bike, gravel bike, and fixies like Kilo TT, they have have similar BB drop.

so i dont get it. i heard peep say Kilo tt dont have ped strike. is ped strike really not about BB drop?

i guess my theory is it has more to do with shorter crank, narrower Q, or taller tires. so i dont really need a new bike...but just need to tweak these things to prevent ped strike. so heres my strategy:
  • larger wheel, like 27.5.
  • taller tires, like 1.9".
  • reduce the Q, shorter BB spindle length by about 10mm, and use Track crank.
  • shorter crank, like 160 mm

Last edited by mtb_addict; 12-23-18 at 11:28 AM.
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Old 12-23-18, 11:33 AM
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Yes to all. Titanium is best. Use red pedals if that doesn't work.
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Old 12-26-18, 05:54 PM
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Do you find your pedals are hitting the ground a lot? If so, you need to do something different, either with your equipment or your riding style. If they are not hitting, why overthink it? Just ride!

Overthink = Q-factor, BB drop, tire size, blah blah blah... ANY fixed gear bike will allow pedals to strike the ground if you lean too far. Maybe your technique is what you should concentrate on first, and if that doesn't work, maybe you'll do better with a single speed (freewheel) bike.

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Old 01-02-19, 09:10 AM
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Originally Posted by mtb_addict View Post
i look at bikes' profile side... i draw a line between both axle...and then i visualize the distance of the BB axis relative to the line. i am surprise that all the different bikes i look at, road bike, gravel bike, and fixies like Kilo TT, they have have similar BB drop.
How about looking at the published geometry specs for the bikes instead of visualizing what it might be? BB drop tends to vary from about 60mm to 75mm on most bikes. Frames intended primarily for fixed gear riding tend to be closer to the 60mm side of that range. 15mm isn't a huge range maybe but it does make a difference.
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Old 01-02-19, 11:15 AM
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Originally Posted by Caliper View Post
How about looking at the published geometry specs for the bikes instead of visualizing what it might be? BB drop tends to vary from about 60mm to 75mm on most bikes. Frames intended primarily for fixed gear riding tend to be closer to the 60mm side of that range. 15mm isn't a huge range maybe but it does make a difference.
Hey hey hey, just guessing from seeing online photos is way better than actually measuring and doing math...come on! You don't get to the moon with math you get there by strapping some rockets on a tube!
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Old 01-02-19, 07:23 PM
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Pedal strike on a track or converted road bike is pretty rare unless you're really cornering hard at high speed. My previous fixed gear bikes were road frame conversions with 175mm cranks and the only time I had pedal strike was when my rear tire blew out in the middle of a corner. So yeah... don't over think it.
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Old 01-13-19, 11:36 PM
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Originally Posted by hairnet View Post
Pedal strike on a track or converted road bike is pretty rare unless you're really cornering hard at high speed. My previous fixed gear bikes were road frame conversions with 175mm cranks and the only time I had pedal strike was when my rear tire blew out in the middle of a corner. So yeah... don't over think it.
I do not agree with this.
Pedal strike on a regular road bike does not require really hard cornering.
I would not be happy with normal road bike pedal clearances on a fixie.
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Old 01-14-19, 01:42 AM
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I have ridden bikes fix gear with a wide range of BB drops and that were very different for pedal strike. (All road bikes. I've never owned a track bike.) My converted Peugeots with 700c wheels struck early and often. On speed bumps too. My Mooney and custom fix gear both have highish BBs and I can hit but it is a pretty good lean when I do. I will never put a fix gear on my Raleigh Competition.

I have always run either Leotard platforms or Shimano 600 semi-platforms, both of which had decent but not great clearance. I keep Q-factors as narrow as possible for my knees and like the side benefit of clearance. I also run 175 cranks on all my current fix gears but ran 168 and 170 on my two Peugeots.

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Old 01-14-19, 08:23 AM
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Pedal strike can only occur when actually pedaling a bicycle, not when looking at online spec sheets.
Bike mfgs have become reasonably competent at designing and producing machines that are suitable for their intended use in the last century or so.
By actually riding such a machine on the open public roads important skills in bike handling and cornering, like not exceeding the limits of traction and/or whacking a pedal on the road surface, will develop.
Or not.

Choosing to ride a FG machine will provide instant negative/positive feedback on a variety of rider inputs, including lean angles in cornering.

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