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rockymountainhigh

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Reply with quote  #1 

Hey everyone...new to the forum...and semi new to gravel riding. 

I got a great deal on a 2015 Specialized Diverge Expert a few weeks back after being on the lookout for a gravel bike for like 3 years now. 

I live at 11,000 feet in Colorado and wanted to go light etc with the bike but never had the money. 

Bike was a "blem" model that my local shop got me. Honestly it is basically brand new. Not sure why it was labelled a blem...could have just been tested and then they could not sell it "new". 

Anyway. I have developed some noise coming out of the bottom bracket now after about 100 miles of riding. I am pushing the bike hard and treat it more like a MTB than a road bike. Gravel riding where I am is not the same as elsewhere in the country. 

What are some options for BB upgrades or something that will be more robust and not start creeking on me every 50 miles after a re-lube? Has the BB30. 

Thanks! Hope to contribute here more. 

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visusest

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Reply with quote  #2 
Check out Wheels Manufacturing’s thread together PF30 BBs. IIRC your bike is OSBB which has stock plastic cups that are notorious for creaking. Any replacement with aluminum cups should help the issue, the thread together type being your best option for eliminating creaking.
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rockymountainhigh

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Reply with quote  #3 

Thanks! 

I am in discussion with my bike mechanic about what to do. 

I may just leave it until it gets really bad. 

It was popping and making noise and then the last ride I went on it was silent. 

So ya no clue. No clue how you get a 4000$ bike and they cheap out on some of the parts. I mean if someone is considering dropping 4k they would not mind 4500 if some of the parts like that were better. I know companies have price points but come on. 

Do you know if the BB30 style BB can be modified to take a different type of BB if I ever wanted to switch out and go for smaller MTB style chain rings in the front? I already put a 11-40 cassette in the back and might go bigger. I ride up above 12k feet regularly and we have some steep steep ass climbs out here. The force of cranking a 40 toother in the back sitting down is still to much sometimes and I get rear wheel spin. If I could pedal with less force it might help keep some traction when crawling up some of these tracks out here. 

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Mark_Landsaat

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Reply with quote  #4 
I would second the wheels MFG thread together BB's. They are a great solution for bikes that have a problem with creaking press fit BB's in general. Regardless whether BB30, PF30 or BB86.

Big fan of the thread together BB here.
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clarksonxc

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Reply with quote  #5 
Quote:
Originally Posted by rockymountainhigh

Do you know if the BB30 style BB can be modified to take a different type of BB if I ever wanted to switch out and go for smaller MTB style chain rings in the front? I already put a 11-40 cassette in the back and might go bigger. I ride up above 12k feet regularly and we have some steep steep ass climbs out here. The force of cranking a 40 toother in the back sitting down is still to much sometimes and I get rear wheel spin. If I could pedal with less force it might help keep some traction when crawling up some of these tracks out here. 



There are adapters that would make a Shimano HTII BB fit, then you could run an XTR or XT crank.  That solution worked for me, but I also have an alloy bike with a clamp on FD that allows me to lower it to fit the smaller chainrings.  If you have a braze on FD you may need an adapter like the WickWerks FitLink.
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NoCoGreg

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Reply with quote  #6 
Quote:
Originally Posted by rockymountainhigh

The force of cranking a 40 toother in the back sitting down is still to much sometimes and I get rear wheel spin. If I could pedal with less force it might help keep some traction when crawling up some of these tracks out here. 

There are Gravel specific cranks with 30/46 and other combinations which would give a slightly lower first gear. 

The problem with mtb cranksets is the BB shell is wider than that of a road bike and most gravel bikes have the same width BB's as road bikes.  That said, the Specialized OSBB is narrower by design so you'll want a knowledgeable shop should you decide to go with a different crankset.

All the tire sees is the power being applied to the pedals and the gear ratio. 

In other words, it doesn't matter to the tire if you have a smaller chainring or a larger cassette cog or a combination of both. 

A 10% larger cog on the cassette (40*1.1 = 44) will reduce the tension in the chain by 10% as the cog now has 10% more leverage over the wheel (ie. the cog turns the wheel easier).

Conversely, going to a 10% smaller chainring (34/1.1 = 31) increases the leverage the crank has on the chain by 10%.  So you'll need 10% less force on the pedal to move the wheel.

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rockymountainhigh

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Reply with quote  #7 

@NoCoGreg

I got a bottom bracket that I am going to have my local mechanic install for me. 

The BB issues seem to resolve themselves in warmer weather I would imagine from pieces parts expanding slightly eliminating the creaking. 

As far as the cassette and chainring etc. I am doing fairly well with the 40 I have. I think it just came down to learning to pedal at a slower cadence, settling in on a rhythm I can sustain and then working to keep my heart rate and overall effort in check. Basically just getting stronger overall. So far so good. 

If I can get used to the setup I have now (I think 50-34 in the front) which shouldn't be an issue it will suit me better on flat roads if I am ever out with the roadie friends. 

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