🏷️ Not eligible for coupons or discounts.
Shimano post-mount disc brake adapters allow you to run your preferred rotor size.
+3mm (SM-MA-F203P/PL2)
+17mm (SM-MA-F220P/PL)
+20mm (SM-MA-F180P/P2)
+20mm (SM-MA-F220P/PL2)
+23mm (SM-MA-F203P/PM)
+40mm (SM-MA-F220P/PM)
+43mm (SM-MA-F203P/P)
Please reach out to us with any questions you may have about anything we sell. We want to make sure you get the right items the first time. Our lifelong riders at Thunder Mountain Bikes are knowledgeable and would love to talk to you!
We currently offer both economy and expedited shipping options through FedEx and USPS.
Most orders totaling over $69 before tax are eligible to ship for free via an economy ground option of our choice.
Due to larger box sizes, handlebars, wheels, and other oversized items, an additional shipping fee will be applied.
Most bikes ship for only $200 within the continental US. Bike shipping to AK, HI, or PR is usually $350, but may incur additional fees depending on the exact delivery location.
If you're in need of something super-quick, please contact us directly. We may be able to overnight your order with an additional fee, depending on your location.
Should there be an issue with the item you bought, or if you no longer need your purchase, we will be happy to set up a return.
Returns may be requested within sixty (60) days of the delivery date. All returned items must be received in new, unused, and uninstalled condition, with the original tags and labels attached and in the original packaging. We cannot accept returns on any items that have been installed or show wear of any kind.
Returns or exchange requests for bikes must be requested by emailing us at sedona@thundermountainbikes.com within fifteen (15) days from the date of delivery. Bikes must be in un-ridden condition. Custom-built bikes may not be returned. Returned bikes incur a $200 restocking fee, and the customer is responsible for the return shipping costs.
Customers are responsible for return shipping fees and may choose the carrier of their choice to handle their product return. We no longer provide shipping labels directly.
For any return shipping questions, please email us at sedona@thundermountainbikes.com after submitting your return request so that we can confirm the shipping information you should use to return your item(s).
We will process your return after receiving your returned item(s) and inspecting their condition. Please allow at least seven (7) days from the receipt of your item to process your refund. We will notify you by email when your return has been processed. All refunds will be returned to the original payment method. No store credit or other refund methods are available.
If you receive defective or damaged products or if we sent you the wrong item(s), please contact us using the phone number or email below.
To request a return, please log in to your customer account by clicking the 
Profile icon in the top right of any page or visit account.thundermountainbikes.com.
1. In the Email field, enter your email address and click Continue.
2. In your email account, open the email sent from our store and copy the six-digit verification code included in the email.
3. Go back to the online store and enter a six-digit verification code to log in.
4. Find and click on the order you want to submit a return for.
5. If your order has more than one item, select only the items you want to return.
6. Select a return reason and add a note for the store if needed.
7. Click Request Return.
Once your return request is approved, you will receive a confirmation by email.
If you have any questions concerning our return policy, please contact us at:
Thunder Mountain always keeps my bike rolling. Thanks again, Kevin.
Wanted to go up to 203 on the rotors - that was the right choice - and these were the right choice. So easy. Should have done it sooner.
OE quality
All good great
Holds caliper on fork
Love these guys have a detailed explanation of the description. Made it easy to choose the right parts. Thank you TMB
Part worked perfectly. Increased rotor size and good to go. Super fast shipping.
this part works. no directions but even i figured it out. be sure to use blue loctite on the bolts or your brakes can and will suddenly go out of true and freak you out with a bad noise. Under NO circumstances use Red loctite.
Very simple to install. Even has the blue thread locker on the included bolts. Just make sure you have enough slack in your brake line to get the angle right.
It is what it is. Nothing more and nothing less. However, this shop always has a good stock of parts and very quick turnaround time from the time of purchase to it getting to your door. This is my local online shop when local bike shops don't have what I need.
This worked perfectly. Surprisingly confusing when researching brake adapters online. I got the SM-MA-F203P/PM, which is well described on this website. My fork is setup for 180mm rotors as well as my frame, used two of these adapters as I am running 203mm rotors front and rear. Worked perfectly.
Perfect service
Fast shipping and Accurate product. Keep up the good service. Thank you.
Product performs as described on website. Used to convert from 140 to 160mm disc brake rotor. Installed easily with the included bolts/hardware. Delivered promptly. Will order from Thunder Mountain again!
