MTB to Cross/Gravel Conversion.
Moderator: Moderator Team
I have an old Seven Sola which I don't ride anymore as I've stopped MTB'ing.
I'm hatching a plan to convert it to a tourer/gravel bike.
I've worked out that the 26" wheels with 2.1" knobblies are the same diameter as a 700c wheel with 25c's on them and the stack and reach will be fine with a 90mm stem and a 450mm fork like it's current Fox 80RLC or a Ritchey rigid offering.
The only issue I have is the old 73mm threaded BB and fitting a double crankset - preferrably with 110bcd spider. Also looking to run this with Ultegra Di2 Disc gruppo.
Does anyone have suggestions for a 50/34 chainset solution that would work?
I'm hatching a plan to convert it to a tourer/gravel bike.
I've worked out that the 26" wheels with 2.1" knobblies are the same diameter as a 700c wheel with 25c's on them and the stack and reach will be fine with a 90mm stem and a 450mm fork like it's current Fox 80RLC or a Ritchey rigid offering.
The only issue I have is the old 73mm threaded BB and fitting a double crankset - preferrably with 110bcd spider. Also looking to run this with Ultegra Di2 Disc gruppo.
Does anyone have suggestions for a 50/34 chainset solution that would work?
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- rasmussloth
- Posts: 314
- Joined: Mon Dec 09, 2013 3:19 pm
- Location: Denmark
Are you sure that 50t chainring will fit and not hit the chainstay?
- breezerboy
- Shop Owner
- Posts: 279
- Joined: Fri Jun 22, 2007 8:14 pm
- Location: Bristol, UK
We have managed this conversion successfully in the past, but it's more dependant on the frame than the crank (crank/ring clearance with chainstay).
Best suggestion is trial fit a right hand crank with rings as is to check clearance. Pretty much any road crank will do as the chainline is pretty universal for this purpose. If you have plenty of clearance then the BB shell can be machined down to 68/70mm to work with hollowtech/gxp cranks. If using an older square taper crank you just use a 73mm specific BB.
If clearance is tight, try a road triple instead. These generally run a spacer each side on hollowtech that can be removed/machined down if you don't want to machine the shell. They also have a slightly higher Q factor if crank arm clearance is an issue. Downside is Di2 compatibility.
Last option is MTB crank with custom spider/rings, but again, you'll need to check ring/stay clearance carefully.
Last problem - If the chainline has to move out for clearance the front mech will not be in the optimum position.
Best suggestion is trial fit a right hand crank with rings as is to check clearance. Pretty much any road crank will do as the chainline is pretty universal for this purpose. If you have plenty of clearance then the BB shell can be machined down to 68/70mm to work with hollowtech/gxp cranks. If using an older square taper crank you just use a 73mm specific BB.
If clearance is tight, try a road triple instead. These generally run a spacer each side on hollowtech that can be removed/machined down if you don't want to machine the shell. They also have a slightly higher Q factor if crank arm clearance is an issue. Downside is Di2 compatibility.
Last option is MTB crank with custom spider/rings, but again, you'll need to check ring/stay clearance carefully.
Last problem - If the chainline has to move out for clearance the front mech will not be in the optimum position.
You could go 46/34 if the 50 is a problem, 46/11 is plenty fast.
Many thanks for the suggestions -really helpful and just what I was looking for. I'm going to check the chain stay clearance today but had (rather stupidly!) forgotten about that aspect.
Once I have that I can look at the alternatives more closely. I really need something bigger than a 46 as I ride a lot of Alpine downhills and regularly spin the 50/11 on those. I might manage a 48/11 but again, clearance is the key as you point out.
Once I have that I can look at the alternatives more closely. I really need something bigger than a 46 as I ride a lot of Alpine downhills and regularly spin the 50/11 on those. I might manage a 48/11 but again, clearance is the key as you point out.
Also i'd question the suitability of 25mm tyres.. way too small for gravel.. 28-35 is better.... perhaps check clearance for this..
And re cyclo-cross, the front triangle is too small on most mtb to shoulder easily... means lifting under the saddle / down tube and not actually shouldering....
All the best with it tho..
And re cyclo-cross, the front triangle is too small on most mtb to shoulder easily... means lifting under the saddle / down tube and not actually shouldering....
All the best with it tho..
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