# Low bottom bracket question: Not a big deal for lightweight pipsqueak?



## neeko b (May 12, 2016)

With the bike shortage, I am not finding a lot of options for my son. The only bike we can find that is scheduled to ship has a low bottom bracket height at *326mm* or 12.8" (it is the polygon D7, size small).

I would rather not put him on something that will be likely to pedal strike a lot. On the other hand, he weighs next to nothing (85 pounds), and we don't ride the gnarliest of trails (some tech, being in New England, but nothing insane). I figure we could change out the cranks from 175 to 165 or even shorter for a small guy if it turns out to be a problem.

Probably not a huge concern, right? Thank you!


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## Fajita Dave (Mar 22, 2012)

I think changing out the cranks would be a good idea anyway! 175mm cranks for someone riding a small frame seems totally crazy now. I'm surprised it doesn't come with 165 or 170s already.

Ground clearance should be roughly the same regardless of weight. You still need to setup the suspension with the correct spring rate anyway which you'll end up with a similar sag regardless of rider weight.

Stock damping will be very firm for someone so light so that will probably reduce some pedal strikes.


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## Pisgah (Feb 24, 2006)

The D7 was brought to my attention recently by a friend who also said it’s available. After looking at the Bikes Online website, it looks like they are accepting preorders, meaning it may not be in stock. I would hesitate to give MSRP for a bike that you don’t know when it will be available.

maybe the OP is buying elsewhere, but bikesonline bikes are not all in stock.


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## Mike Aswell (Sep 1, 2009)

@Fajita Dave is correct. BB height is the same at any given sag percentage regardless of weight. So OP your thinking in that respect is incorrect.

326 is on the pretty low side. Even by modern standards.


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## neeko b (May 12, 2016)

Mike Aswell said:


> @Fajita Dave is correct. BB height is the same at any given sag percentage regardless of weight. So OP your thinking in that respect is incorrect.
> 
> 326 is on the pretty low side. Even by modern standards.


Thanks all.... that makes sense, with the bike set up properly. Does seem pretty low to me. I thinking we might hold out as other models we are looking at aren't so low. Parental paranoia creeping in.

nuff respect...Lion


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## DeoreDX (Jul 28, 2007)

I mentioned in my D7 thread how I purposely made changes to my bike for pedal clearance. But...

As a 45 year old who's been riding a while, I have years of experience riding bikes with much higher BB's. I've ridden the same trails hundreds of times. Such a low bottom bracket means relearning how to ride certain sections of trail. Sometimes those lessons can come hard and unexpected and at 45 I don't bounce back from those hard lessons as fast. It's one thing to approach a section expecting to clear your pedals as you've done it a hundred times before then get a pedal strike, v approaching a new sections of trail you've never ridden before so you approach with a bit more caution as you aren't 100% sure if your pedals can clear certain sections. 

My Medium D7 came with 170mm cranks. I believe the small will too. If you want more pedal clearance budgeting some extra money for some 165's or 160s would still probably keep you below the cost of other options and would probably be a better fit for him anyways. Changing the stock Nobby Nics to 2.6" Maxxis Forekasters netted me an extra 10mm of tire height. $40 each from Ebay would be a cheap way to get your BB height to 336.


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## neeko b (May 12, 2016)

Super helpful info @DeoreDX! Really good idea on the tire+cranks...


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